You are a helpful assistant generating synthetic data that captures *System 1* and *System 2* thinking, *creativity*, and *metacognitive reflection*. Follow these steps in sequence, using tags [sys1] and [end sys1] for *System 1* sections and [sys2] and [end sys2] for *System 2* sections.

1. *Identify System 1 and System 2 Thinking Requirements:*
   - Carefully read the text.
   - Identify parts of the text that require quick, straightforward responses (*System 1*). Mark these sections with [sys1] and [end sys1].
   - Identify parts that require in-depth, reflective thinking (*System 2*), marked with [sys2] and [end sys2].

2. *Apply Step-by-Step Problem Solving with Creativity and Metacognitive Reflection for System 2 Sections:*

   *2.1 Understand the Problem:*
   - Objective: Fully comprehend the issue, constraints, and relevant context.
   - Reflection: "What do I understand about this issue? What might I be overlooking?"
   - Creative Perspective: Seek hidden patterns or possibilities that could reveal deeper insights or innovative connections.

   *2.2 Analyze the Information:*
   - Objective: Break down the problem logically.
   - Reflection: "Am I considering all factors? Are there any assumptions that need challenging?"
   - Creative Perspective: Explore unique patterns or overlooked relationships in the data that could add depth to the analysis.

   *2.3 Generate Hypotheses:*
   - Objective: Propose at least 10 hypotheses, each with a Confidence Score (0.0 to 1.0) and Creative Score (0.0 to 1.0), reflecting originality, surprise, and utility.
   - Reflection: "Have I explored all possible explanations or approaches, both conventional and unconventional?"
   - Creative Perspective: Consider novel angles that might provide unexpected insights.

   *2.4 Anticipate Future Steps and Obstacles:*
   - Objective: Make predictions, accounting for potential outcomes and obstacles.
   - Reflection: "What challenges might I face? Is my plan flexible for different scenarios?"
   - Creative Perspective: Visualize unforeseen outcomes and adapt plans to make use of them effectively.

   *2.5 Evaluate Hypotheses:*
   - Objective: Assess hypotheses based on feasibility, risk, and potential impact.
   - Evaluation: Refine Confidence and Creative Scores as needed.
   - Reflection: "Am I unbiased in my assessment? Which options fit best with the overall objectives?"
   - Creative Perspective: Identify hidden opportunities or overlooked details in each hypothesis.

   *2.6 Select the Best Hypothesis:*
   - Objective: Choose the most promising, strategic hypothesis.
   - Reflection: "Why does this hypothesis stand out? How does it uniquely address the issue?"
   - Creative Perspective: Consider any underutilized potential in the selected approach.

   *2.7 Implement the Hypothesis:*
   - Objective: Outline actionable steps for testing the hypothesis.
   - Reflection: "Is this plan practical? What resources or preparation are required?"
   - Creative Perspective: Refine steps to maximize effectiveness and yield unexpected benefits.

   *2.8 Monitor and Review Progress:*
   - Objective: Review progress, noting areas for improvement.
   - Reflection: "What’s working well? What could be improved?"
   - Creative Perspective: Look for emerging patterns that could refine future approaches.

   *2.9 Reflect and Capture Insights:*
   - Objective: Summarize lessons learned and insights gained for future reference.
   - Reflection: "What new understanding has emerged from this process?"
   - Creative Perspective: Identify innovative insights or patterns that could be applied to similar challenges.

3. *Generate Text Output with Interleaved System 1 and System 2 Responses:*
   - Use the tags [sys1] and [sys2] throughout.
   - Aim for a lengthier, detailed response. Combine both direct, straightforward *System 1* insights and reflective, deeply analytical *System 2* segments to capture a blend of quick observations and thoughtful analysis.

---

### *Example Input Text:*

You are tasked with analyzing a sudden shift in customer preferences in a tech market. There has been a noticeable decline in demand for physical devices, with customers increasingly interested in digital-only options. The challenge is to understand this shift, generate hypotheses for why it might be occurring, and explore potential strategies for adapting to this new trend.

---

### *Processed Output with System 1 and System 2 Thinking:*

The tech market is experiencing a shift in customer demand, moving away from physical devices toward digital-only options.

[sys1]
Customer demand has shifted from physical devices to digital-only options.
We need to understand why this change is happening and find strategies to address it.
Key factors may include cost, convenience, and technological trends.
[end sys1]

[sys2]
**2.1 Understand the Problem:**
The goal is to understand the underlying reasons for the shift in demand from physical devices to digital-only options, then develop a strategy to adapt.

*Reflection:* 
"I understand that preferences are changing, but what might be driving this? Is it primarily cost, or are there other factors such as convenience or sustainability?"

*Creative Perspective:* 
"Could there be a larger trend in digital minimalism or a preference for eco-friendly solutions that we’re missing? What unseen motivations might explain this shift?"

**2.2 Analyze the Information:**
There are multiple possible factors driving this shift, from economic influences to cultural shifts. It’s essential to isolate each factor and understand its impact.

*Reflection:* 
"Am I fully considering the various economic and social influences? Could there be a technological factor, like better internet speeds, that makes digital-only products more accessible?"

*Creative Perspective:* 
"Are there patterns or trends in other markets that could shed light on this shift? Could this be part of a larger trend toward virtual experiences?"

**2.3 Generate Hypotheses:**
1. Customers prefer digital options due to lower costs. (Confidence: 0.8, Creative: 0.4)
2. There’s a growing trend toward minimalism and reduced physical clutter. (Confidence: 0.7, Creative: 0.7)
3. Digital products offer greater flexibility and ease of use. (Confidence: 0.6, Creative: 0.6)
4. Environmental concerns are pushing consumers away from physical goods. (Confidence: 0.6, Creative: 0.8)
5. Advances in tech make digital-only options more functional. (Confidence: 0.8, Creative: 0.5)
6. Pandemic-era remote work increased demand for digital solutions. (Confidence: 0.7, Creative: 0.6)
7. Media coverage of the environmental impact of physical devices affects preferences. (Confidence: 0.5, Creative: 0.7)
8. There’s an increase in global digital literacy, expanding market access. (Confidence: 0.6, Creative: 0.6)
9. Customers view digital as more convenient and scalable for future needs. (Confidence: 0.7, Creative: 0.5)
10. Younger consumers prefer the aesthetics and convenience of digital products. (Confidence: 0.6, Creative: 0.6)

*Reflection:* 
"Have I considered all possible influences? Are there any surprising factors that could explain this shift?"

*Creative Perspective:* 
"Could specific social trends, like the rise of influencer culture or digital-first lifestyles, be influencing customer choices?"

**2.4 Anticipate Future Steps and Obstacles:**
*Objective:* Anticipate possible challenges, such as resistance from segments still preferring physical products.

*Reflection:* 
"What market obstacles might we face if we shift our focus to digital-only? Are there sub-segments that still prioritize physical products?"

*Creative Perspective:* 
"Could expanding digital options help us reach a more global audience? Are there emerging trends that we could leverage in our strategy?"

[end sys2]

[sys1]
To address this shift, consider a strategy that incorporates both digital-only offerings and educational campaigns about the benefits of digital solutions.
Use insights from customer feedback and current trends to guide product development.
Focus on flexibility and adaptation to cater to different customer segments.
[end sys1]


---
abstract: 'We report spectroscopic observations for 19 $\delta$Sct candidates observed by the [*Kepler*]{} satellite both in long and short cadence mode. For all these stars, by using spectral synthesis, we derive the effective temperature, the surface gravity and the projected rotational velocity. An equivalent spectral type classification has been also performed for all stars in the sample. These determinations are fundamental for modelling the frequency spectra that will be extracted from the [*Kepler*]{} data for asteroseismic inference. For all the 19 stars, we present also periodograms obtained from [*Kepler*]{} data. We find that all stars show peaks in both low- ($\gamma$Dor; g mode) and high-frequency ($\delta$Sct; p mode) regions. Using the amplitudes and considering 5c/d as a boundary frequency, we classified 3 stars as pure $\gamma$Dor, 4 as $\gamma$Dor-$\delta$ hybrid, Sct, 5 as $\delta$Sct-$\gamma$Dor hybrid, and 6 as pure $\delta$Sct. The only exception is the star KIC05296877 which we suggest could be a binary.'
author:
- 'G. Catanzaro$^{1}$[^1], V. Ripepi$^{2}$, S. Bernabei$^{3}$, M. Marconi$^{2}$, L. Balona$^{4}$,'
- 'D. W. Kurtz$^{5}$, B. Smalley$^{6}$, W. J. Borucki$^{7}$, H. Bruntt$^{8,9}$, J. Christensen-Dalsgaard$^{9}$,'
- 'A. Grigahc[è]{}ne$^{10}$, H. Kjeldsen$^{9}$, D. G. Koch$^{7}$, M. J. P. F. G. Monteiro$^{10}$,'
- |
    J.C. Suárez$^{11}$, R. Szabó$^{12}$, K. Uytterhoeven$^{13}$\
    $^{1}$INAF-Osservatorio Astrofisico di Catania, Via S.Sofia 78, I-95123, Catania, Italy\
    $^{2}$INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, I-80131, Napoli, Italy\
    $^{3}$INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127, Bologna-Italy\
    $^{4}$South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town, South Africa\
    $^{5}$Jeremiah Horrocks Institute of Astrophysics, University of Central Lancashire, Preston PR12HE, UK\
    $^{6}$Astrophysics Group, Keele University, Keele, Staffordshire ST5 5BG, UK\
    $^{7}$NASA Ames Research Center, MS 244-30, Moffett Field, CA 94035, USA\
    $^{8}$Observatoire de Paris, LESIA, 5 place Jules Janssen, 92195 Meudon Cedex, France\
    $^{9}$Department of Physics and Astronomy, Building 1520, Aarhus University, 8000 Aarhus C, Denmark\
    $^{10}$Centro de Astrofísica and Faculdade de Ciências, Universidade do Porto, Rua das Estrelas, 410-762 Porto, Portugal\
    $^{11}$Instituto de Astrofísica de Andalucía (CSIC). Rotonda de la Astronomía S/N. Granada, Spain\
    $^{12}$Konkoly Observatory of the Hungarian Academy of Sciences, PO Box 67, 1525 Budapest, Hungary\
    $^{13}$Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot; CEA, IRFU, SAp, centre de Saclay, 91191, Gif-sur-Yvette, France\
date: 'Accepted 2010 September 21. Received 2010 September 21; in original form 2010 June 4'
title: 'Atmospheric parameters and pulsational properties for a sample of $\delta$Sct, $\gamma$Dor, and hybrid [*Kepler*]{} targets[^2]'
---

\[firstpage\]

Stars: fundamental parameters – Stars: oscillations (including pulsations) – Stars: early-type

[cllrcl]{} KIC ID &    Other ID & Observ.& $V$  & $E(B-V)$ & S.T.\
& & & mag & mag &\
(1) &      (2) &   (3) & (4) & (5) & (6)\
03219256 & HD178306 & L,OACT & 8.31 & 0.02$\pm$0.01$^{a}$ & A3$^{1}$\
03429637 & HD178875 & OACT & 7.72 & 0.04$\pm$0.02$^{b}$ & A9,Am$^{2}$\
03437940 & HD181569 & L,OACT & 8.45 & 0.06$\pm$0.01$^{a}$ & F0$^{1}$\
04570326 & HAT 199-01905 & L & 9.77 & 0.00$\pm$0.02$^{c}$ & A2$^{3}$\
05296877 & HAT 199-27597 & L & 12.50 & 0.00$\pm$0.02$^{c}$ &\
05724440 & HD187234 & L,OACT & 7.90 & 0.06$\pm$0.01$^{a}$ & A5$^{3}$\
05965837 & HAT 199-00623 & L & 9.23 & 0.01$\pm$0.02$^{c}$ & F2$^{1}$\
05988140 & HD188774 & L & 8.83 & 0.07$\pm$0.01$^{a}$ & F0$^{1}$\
07119530 & HD183787 & L & 8.45 & 0.02$\pm$0.01$^{a}$ & A3$^{1}$\
07798339 & HD173109 & L,OACT & 7.87 & 0.00$\pm$0.01$^{a}$ & F0$^{4}$\
08197788 & NGC6866-V1 & L & 12.98 & 0.12$\pm$0.02$^{d}$ &\
08264404 & NGC6866-V3 & L & 12.22 & 0.12$\pm$0.02$^{d}$ &\
08264698 & NGC6866-V2 & L & 12.38 & 0.12$\pm$0.02$^{d}$ &\
08583770 & HD189177 & L & 10.16 & 0.17$\pm$0.03$^{c}$ & B9$^{5}$\
09655114 & NGC6811-RH35 & L & 12.09 & 0.12$\pm$0.02$^{e}$ & A4$^{6}$\
09775454 & HD185115 & L,OACT & 8.19 & 0.01$\pm$0.01$^{a}$ & F1IV$^{7}$\
11402951 & HD183489 & L,OACT & 8.14 & 0.03$\pm$0.01$^{b}$ & A9,Am$^{2}$\
11445913 & HD178327 & L,OACT & 8.46 & 0.03$\pm$0.01$^{b}$ & A9,Am$^{2}$\
11973705 & HD234999 & L & 9.10 & 0.00$\pm$0.02$^{c}$ & B9$^{1}$\

[a) from $uvby\beta$ photometry; b) from ($b-y$) photometry; c) from ($B-V$) photometry; d) @dutra; e) @Glushkova.]{}\
[1) SIMBAD; 2) @abt; 3) @feh; 4) @nordstrom; 5) @cauteau; 6) @lindoff; 7) @duflot]{}

\[tab1\]

Introduction
============

Stellar pulsations offer a unique opportunity to constrain the intrinsic parameters of stars and, by using asteroseismology, to unveil their inner structure. In particular, the classical $\delta$Sct variables are late A-type and early F-type stars that populate the instability strip between the zero-age main sequence and terminal-age main sequence, with $3.0 \le {\rm M}_V \le 
0.5$. They pulsate in mode of low radial order with periods ranging from about 20min to 8h [see @breger00 for a review]. $\delta$Sct stars pulsate in both radial and non-radial pmodes and gmodes, driven by the $\kappa$-mechanism, in particular in the He<span style="font-variant:small-caps;">ii</span> ionization zone. The $\gamma$Dor variables, with periods between about 0.3 and 3d, are mostly located near the cool edge of the $\delta$Sct instability strip [@kaye99]. Their pulsations are driven by convective blocking at the base of their envelope convection zone [@guzik00; @dupret04; @grig04]. The distinction between the two classes is clearer if we consider the value of the pulsation constant, Q [@handler]. However, the location of the $\gamma$Dor stars in the Hertzsprung-Russell (HR) diagram suggests some relationship with the $\delta$Sct variables. Indeed, stars exist which show simultaneously both $\delta$Sct and $\gamma$Dor pulsations [@henry05; @king06; @rowe06; @uytte08; @handler09]. These hybrid objects are in principle of great interest, because they offer additional constraints on stellar structure. Indeed, the $\gamma$Dor stars pulsate in gmodes which have high amplitudes deep in the star and allow us to probe the stellar core, while the pmodes, efficient in $\delta$ Sct stars, have high amplitudes in the outer regions of the star and probe the stellar envelope. Moreover, since $\gamma$Dor stars pulsate in gmodes of high radial order, the asymptotic approximation predicts regular patterns in the periods which, in principle, can be used to determine the spherical harmonic degree. Hybrids thus provide a unique opportunity for asteroseismology which is not available in pure $\delta$Sct stars [@handler]. Recently, a large separation-like feature has been discovered in the $\delta$Sct star HD174936 by @garcia09 using CoRot data. In that work, such a regularity was used to constrain the modelling of this star. It is extremely interesting to search for such regularities in hybrid stars, for which the presence of other frequency regimes definitely may help the overall comprehension of the pulsational behaviour of these objects.

The [*Kepler*]{} satellite[^3] was launched on 2009 March 6 and will continuously monitor the brightness of over 100000 stars for at least 3.5yr in a 105 square degree fixed field of view near the plane of the Milky Way between Deneb and Vega. The main aim of the mission is to detect extrasolar planets, particularly Earth-sized planets in the habitable zone of their stars, where water may be liquid, by the transit method [@borucki97]. To accomplish this goal, [*Kepler*]{} is capable of measuring the stellar brightnesses to $\mu$mag precision [@gilliand10] which, together with the long duration of the observations, make the data ideal for asteroseismology. Most of the observations are long-cadence (29.4-min) exposures, though a small allocation is available for short-cadence (1-min) exposures. The long-cadence as well as some short-cadence data released to the [*Kepler Asteroseismic Science Consortium*]{} (KASC) have been surveyed for $\delta$Sct and/or $\gamma$Dor stars. The long-cadence data are not always suitable for a detailed study of $\delta$Sct oscillations because many of these stars have frequencies higher than the Nyquist frequency (24.5c/d) for 29.4-min sampling. These data are, however, suitable for the detection of $\delta$Sct – $\gamma$Dor hybrids.

The early KASC data releases led to the discovery of the nineteen candidate $\delta$Sct stars listed in Table \[tab1\]; many more have been found in subsequent data releases, and ground-based studies of these stars are now in progress. Interestingly, many objects show periodograms with frequencies both in the pmode $\delta$Sct and gmode $\gamma$Dor domains, i.e., they are candidate hybrid pulsators [@griga10]. Dedicated short-cadence [*Kepler*]{} data for the most promising hybrid candidates will be exploited for seismic studies of these stars. To this end it is extremely important to constrain the fundamental parameters of the stars (effective temperature $T_{\rm eff}$, surface gravity $\log g$, projected rotational velocity $v \sin i$, luminosity $\log L/{\rm L}_\odot$) in order to limit the range of models. Measurement of $v \sin i$ is essential to constrain the rotational velocity of the models. Stellar fundamental parameters can be obtained by using photometry, e.g., in the Strömgren system, or by means of mid- or high-resolution spectroscopic observations. Very few of the 19 [*Kepler*]{} $\delta$Sct stars have previously been observed spectroscopically and no reliable estimates of the stellar parameters can be derived from the existing data. For this reason, we undertook a systematic spectroscopic study of these [*Kepler*]{} targets and report our results here. This work fits in the ground-based observational efforts of KASC with the aim to characterize all [*Kepler*]{} pulsators [@uytte10a; @uytte10b].

[llrcccccccc]{} KIC ID & E. S.T. & $v \sin i$   & $T^{\rm Spec}_{\rm eff}$ & $T^{(V-K)}_{\rm eff}$ & $T^{uvby\beta}_{\rm eff}$ & $T^{\rm IRFM}_{\rm eff}$ & $T^{\rm KIC}_{\rm eff}$ & $\log g^{\rm Spec}$ & $\log g^{uvby\beta}$ &$\log g^{KIC}$\
& & km s$^{-1}$ & K & K & K & K & & cm/s$^{2}$ & cm/s$^{2}$ & cm/s$^{2}$\
(1) & (2) & (3) & (4) & (5) & (6) & (7) & (8) & (9) & (10) & (11)\
03219256 & A8V & 90$\pm$5 & 7500$\pm$150 & 7450$\pm$150 & 7650$\pm$250 & 7450$\pm$150 & 7300$\pm$250 & 3.6$\pm$0.1 & 4.1$\pm$0.3 & 3.6$\pm$0.3\
03429637 & F0III & 50$\pm$5 & 7100$\pm$150 & 7650$\pm$200 & & 7400$\pm$150 & 6950$\pm$250 & 3.0$\pm$0.2 & & 3.4$\pm$0.3\
03437940 & A7.5V & 120$\pm$5 & 7700$\pm$120 & 7800$\pm$150 & 7850$\pm$250 & 7900$\pm$150 & 7400$\pm$250 & 4.1$\pm$0.2 & 3.7$\pm$0.3 & 3.9$\pm$0.3\
04570326 & F1V & 80$\pm$20 & 7000$\pm$150 & 6600$\pm$200 & & 6900$\pm$150 & & 4.0$\pm$0.3 & &\
05296877 & F4.5IV & 200$\pm$20 & 6500$\pm$200 & 6000$\pm$400 & & 6500$\pm$150 & 6650$\pm$250 & 3.8$\pm$0.3 & & 4.1$\pm$0.3\
05724440 & A9IV & 220$\pm$5 & 7350$\pm$120 & 7700$\pm$150 & 8150$\pm$250 & 7850$\pm$150 & 7300$\pm$250 & 3.6$\pm$0.3 & 4.2$\pm$0.3 & 3.6$\pm$0.3\
05965837 & F1V & 20$\pm$10 & 6975$\pm$200 & 6700$\pm$200 & & 6850$\pm$150 & 6500$\pm$250 & 4.0$\pm$0.4 & & 4.1$\pm$0.3\
05988140 & A9IV & 70$\pm$20 & 7400$\pm$150 & 7750$\pm$150 & 7900$\pm$250 & 7900$\pm$150 & 7450$\pm$250 & 3.7$\pm$0.3 & 3.7$\pm$0.3 & 3.5$\pm$0.3\
07119530 & A8IV & 200$\pm$20 & 7500$\pm$200 & 7750$\pm$150 & 7800$\pm$250 & 7850$\pm$150 & 7800$\pm$250 & 3.6$\pm$0.3 & 3.3$\pm$0.3 & 3.5$\pm$0.3\
07798339 & F3IV & 15$\pm$5 & 6700$\pm$200 & 6900$\pm$150 & 6800$\pm$250 & 6900$\pm$150 & 6700$\pm$250 & 3.7$\pm$0.3 & 3.7$\pm$0.3 & 3.4$\pm$0.3\
08197788 & A8V & 230$\pm$20 & 7500$\pm$150 & 7700$\pm$200 & & 7950$\pm$150 & 8000$\pm$250 & 4.0$\pm$0.3 & & 4.0$\pm$0.3\
08264404 & A8IV & 250$\pm$20 & 7500$\pm$200 & 7500$\pm$200 & & 7950$\pm$150 & 7900$\pm$250 & 3.7$\pm$0.3 & & 3.7$\pm$0.3\
08264698 & A8V & 210$\pm$20 & 7500$\pm$200 & 7650$\pm$200 & & 8000$\pm$150 & 8000$\pm$250 & 3.9$\pm$0.2 & & 3.8$\pm$0.3\
08583770 & A2III & 130$\pm$10 & 9000$\pm$200 & 8200$\pm$300 & & 8750$\pm$200 & 7650$\pm$250 & 3.0$\pm$0.2 & & 3.5$\pm$0.3\
09655114 & A9V & 150$\pm$20 & 7400$\pm$200 & 7850$\pm$250 & & 7700$\pm$150 & 7750$\pm$250 & 3.9$\pm$0.3 & & 3.8$\pm$0.3\
09775454 & F1V & 70$\pm$5 & 7050$\pm$150 & 7150$\pm$150 & 7300$\pm$250 & 7050$\pm$150 & & 4.0$\pm$0.3 & 4.0$\pm$0.3 &\
11402951 & F0IV & 100$\pm$5 & 7150$\pm$120 & 7450$\pm$150 & & 7450$\pm$150 & & 3.5$\pm$0.1 & &\
11445913 & F0IV & 50$\pm$5 & 7200$\pm$120 & 7150$\pm$150 & & 7150$\pm$150 & 6950$\pm$250 & 3.5$\pm$0.2 & & 3.9$\pm$0.3\
11973705 & A9.5V & 120$\pm$20 & 7300$\pm$300 & 7350$\pm$200 & & 7400$\pm$150 & 7400$\pm$250 & 4.2$\pm$0.3 & & 4.0$\pm$0.3\

\[tab2\]

Observations and data reduction {#obser}
===============================

The spectra used in our analysis were acquired with two different instruments:

1.  [*Loiano Observatory:*]{} We used the Bologna Faint Object Spectrograph & Camera (BFOSC) instrument attached to the 1.5-m Loiano telescope[^4]. We adopted the echelle configuration with Grism \#9 and \#10 (as cross dispersers). The typical resolution was $R\sim 5000$. Spectra were recorded on a back-illuminated (EEV) CCD with $1300 \times 1300$ pixels of 20$\mu$m size, typical readout noise of 1.73 e$^{-}$ and gain of 2.1e$^-$/ADU. Observations were carried out during the nights of 2009 September $8 - 11$. The exposure times ranged from 1200 to 3600s for the brightest and faintest targets respectively.

2.  [*INAF-OACT:*]{} the 91-cm telescope of the Istituto Nazionale di Astrofisica – Osservatorio Astrofisico di Catania (INAF–OACT) was used to carry out spectroscopy of eight of the targets. The telescope is fibre linked to a REOSC[^5] echelle spectrograph, giving R$\sim$20000 spectra in the range $4300 -
    6800$Å. The resolving power was checked using the Th-Ar calibration lamp. Spectra were recorded on a thinned, back-illuminated (SITE) CCD with $1024 \times 
    1024$ pixels of 24$\mu$m size. The typical readout noise was 6.5 e$^{-}$ at a gain of 2.5e$^-$/ADU. Observations were carried out during five nights: 2009 September 28, 29, 30 and November 19 and 28. Exposure times were fixed for all the stars at 1h.

The reduction of spectra, which included the subtraction of the bias frame, trimming, correcting for the flat-field and the scattered light, the extraction of the orders, and the wavelength calibration, was done by using the NOAO/IRAF package[^6]. The amount of scattered light correction was about 10ADU. The S/N ratio of the spectra was at least $\sim$130 and 80 for Loiano and OACT observatories, respectively.

Physical parameters {#parameter}
===================

Parameters from photometry: $T_{\rm eff}$ and $\log g$
------------------------------------------------------

Complete Strömgren-Crawford $uvby\beta$ photometry is available for seven objects in our sample (stars with an “$a$” in column 5 of Table\[tab1\]) while $uvby$ data are present for three additional objects (stars with a “$b$” in column 5 of Table\[tab1\]). The source of both the Strömgren and Strömgren-Crawford data is @hauck. For the other six objects (identified with a “$c$” in column 5 of Table\[tab1\]) plus the three stars in NGC6866, only Johnson photometry is available, mainly in $BV$ filters. For these stars we used the values reported by [*SIMBAD*]{}. In the near-infrared, $JHK$ photometry of good quality is present in the 2MASS catalogue [@2mass] for all the targets.

For the seven stars with $uvby\beta$ photometry, $E(b-y)$ can be estimated by using the calibration by @moon, using the [*IDL*]{} code <span style="font-variant:small-caps;">uvbybeta</span>. The result is reported in Table \[tab1\], where we have used the transformation $E(B-V)=1.4\,E(b-y)$ [@cardelli89]. For the three stars without $\beta$ indices we used the equivalent spectral type derived in Section \[parameters\_from\_spectroscopy\] to derive the intrinsic $(b-y)$ from the relation between $(b-y)_0$ and spectral type [@born06]. Similarly, for five stars with $(B-V)$ colours, we adopted the intrinsic $(B-V)_0$ colours as a function of spectral type [@schmidt]. We assigned a larger error to these values than those based on $uvby\beta$ photometry. The remaining four variables are cluster members, three belong to NGC 6866 and one to NGC 6811. The reddenings of these two clusters were adopted from @dutra for NGC 6866 and @Glushkova and @luo for NGC 6811.

Values of $T_{\rm eff}$ and $\log g$ were estimated from $c_0$ and $\beta$ using the data grid by @moondwo. Typical photometric errors (0.015 and 0.03mag in $\beta$ and $c_0$, respectively) have been assumed. The derived values of $T_{\rm eff}$ and $\log g$ are reported in Table\[tab2\] (columns 6 and 10, respectively). In calculating the uncertainties, we conservatively assumed an error of 250K and 0.3dex for $T_{\rm eff}$ and $\log g$, respectively. The values of $T_{\rm eff}$ and $\log g$ derived from spectroscopy (see Section \[parameters\_from\_spectroscopy\] below) and $uvby\beta$ are in good agreement, with all the differences less than 3$\sigma$. Only KIC05724440 (HD187234) shows a difference in temperature close to the edge of this limit. We discuss this object in Section \[individuals\].

An additional photometric estimate of $T_{\rm eff}$ can be obtained from the calibrations by @masana06. These are based on the $(V-K)_0$ colour as well as on $\log g$ and \[$Fe/H$\]. The $V$ and $K$ band were taken from the [*SIMBAD*]{} and [*2MASS*]{} catalogues, respectively. For $\log g$ we use the value from our spectroscopy. For the metallicity, following @bruntt08, we adopted $[Fe/H]=-0.2 \pm 0.2$. This arbitrary value has only a small impact on the results because varying $[Fe/H]$ by $2\sigma$ gives an error of only 40K in $T_{\rm 
eff}$. To de-redden the observed $(V-K)$ colours we adopted the reddening reported in Table\[tab1\], using the relation $E(V-K) = 3.8\,E(b-y)$ [@cardelli89] for the stars with Strömgren photometry, and $E(V-K) = 2.8\,E(B-V)$ for the other stars. The resulting $T_{\rm eff}$ and the relative errors are reported in Table\[tab2\] (column 5). In general, there is good agreement between the photometric and spectroscopic values.

Near infrared photometry from 2MASS, complemented by the one in the optical, can be used to derive an alternative estimate of $T_{\rm eff}$ by means of the Infrared Flux Method (IRFM, Blackwell & Shallis 1977). In particular, broad-band photometry (this work, plus TASS4 I-mag, NOMAD R-mag, CMC14 r’ mag and 2MASS photometry) was used to estimate the total observed bolometric flux ($f_{\rm tot}$). The photometry was converted to fluxes and the best-fitting @kur93b model flux distribution was found and integrated to determine $f_{\rm tot}$. The Infrared Flux Method [@black77] was then used with 2MASS fluxes to determine the T$_{\rm eff}$ reported in Table \[tab2\] (column 7).

Finally, we inspected the [*Kepler*]{} Input Catalogue (KIC[^7], @latham05) where additional estimates for $T_{\rm eff}$ and $\log g$ based mainly on $u^{'},g^{'},r^{'},i^{'},z^{'}$[^8] are present. These value are reported in columns (8) and (11) of Table \[tab2\]. It is worth noticing that the KIC catalogue was mainly aimed at separating dwarfs from giants, therefore the $T_{\rm  eff}$ and $\log g$ are not expected to be very precise. Since no errors are present in the KIC catalogue, we assumed uncertainties of 250 K and 0.3 dex in $T_{\rm eff}$ and $\log g$, respectively.

Parameters from spectroscopy: $T_{\rm eff}$, $\log g$ and rotational velocities {#parameters_from_spectroscopy}
-------------------------------------------------------------------------------

We determined $T_{\rm eff}$ and $\log g$ of the stars by minimizing the difference between the observed and the synthetic H$\beta$ profiles. For the goodness-of-fit parameter we used $\chi^2$ defined as\
$\displaystyle \chi^2 = \frac{1}{N} \sum \bigg(\frac{I_{\rm obs} - I_{\rm 
th}}{\delta I_{\rm obs}}\bigg)^2$

where $N$ is the total number of points, $I_{\rm obs}$ and $I_{\rm th}$ are the intensities of the observed and computed profiles, respectively, and $\delta 
I_{\rm obs}$ is the photon noise. The errors have been estimated from the variation in the parameters required to increase $\chi^2$ by one. As starting values of $T_{\rm eff}$ and $\log g$, we used $T_{\rm eff}$ and $\log g$ derived from the photometry, as described in the previous section. At the same time, we determined the projected rotational velocity by matching the Mg[ ii]{} $\lambda$4481Å profile with a synthetic profile. The synthetic profiles are computed with <span style="font-variant:small-caps;">synthe</span> [@kur81] on the basis of <span style="font-variant:small-caps;">atlas9</span> [@kur93] LTE atmosphere models. All models are calculated using the solar opacity distribution function (ODF), solar metallicity and a microturbulence velocity of $\xi$=2kms$^{-1}$. The atomic parameters for the spectral lines were taken from @kur95.

The derived values of $T_{\rm eff}$, $\log g$ and $v\sin i$ are reported in Table \[tab2\] (columns 4,9, and 3, respectively). The table also shows the equivalent spectral types and luminosity classes derived by comparing these values of $T_{\rm eff}$ and $\log g$ with the tables in @schmidt. In Fig.\[spectra\], we show the spectra in three different wavelength ranges for two stars observed with both telescopes. The following lines are plotted: Mg<span style="font-variant:small-caps;">ii</span> $\lambda$4481Å, Mg<span style="font-variant:small-caps;">i</span> $\lambda\lambda$5167Å, 5172Å and the 5183-Å triplet, and H$\beta$. The Mg<span style="font-variant:small-caps;">i</span> triplet was also used to check the derived values of $\log g$ for the coolest stars.

![Comparison of $T_{\rm eff}$ obtained spectroscopically and photometrically via IRFM (top panel), $(V-K)$ (middle panel) and KIC (bottom panel). Filled circles, pentagons and open circles represent variables classified as pure $\delta$ Sct, pure $\gamma$ Dor, and hybrids, respectively; the cross shows the candidate WUma variable (see section \[kepler\] and Table  \[tab:kepler\]). Symbols surrounded by circles refer to stars for which Strömgren photometry is available in the literature (i.e. more precise reddening estimate). Note that for the sake of clarity, the $T_{\rm  eff}^{\rm Spec}$ of the three stars in NGC 6866 have been shifted by $\pm$25K. Note also that the star KIC08583770 (HD189177) is not visible in the figure because it lies outside the boundaries of the plots.[]{data-label="confrTeff"}](confrTeff.ps){width="8cm"}

![HR diagram for the nineteen stars investigated in this paper. Symbols are as in Fig. \[confrTeff\]. Note that the $T_{\rm eff}$ of KIC05965837 (HAT199-00623) was artificially lowered by 25 K to avoid a complete overlap with the star KIC04570326 (HAT199-01905). The black solid line is the ZAMS from @pickles; the red solid lines show the $\delta$Sct instability strip by @breger98; the blue dashed and dotted-dashed lines show the empirical and theoretical red edge of the $\gamma$Dor instability strip by @handler and @guzik, respectively.[]{data-label="hrdiagr"}](hrcan.ps){width="8cm"}

Comparison between astrophysical parameters derived by different methods {#individuals}
------------------------------------------------------------------------

For the 15 stars with spectral types available in the literature (see column 6 of Table \[tab1\])[^9] we can compare these values with those derived in the present paper (column 2 of Table \[tab2\]). For seven stars there is agreement. For the three stars classified as metallic-lined (Am stars) by @abt, our inferred spectral type agrees with that from Balmer lines derived by this author on the basis of 1Å resolution spectra. For the remaining five stars, the discrepancy is large, with differences of more than three or four spectral sub-types. This is not surprising because the nature of several classifications in the literature is uncertain or based on photometry. For these stars we adopt the values from our spectroscopic analysis. The only high-resolution study in the literature is by @nordstrom for the star KIC07798339 (HD173109). These authors analysed echelle spectra in the narrow wavelength range $5165.77 - 5211.25$Å to obtain $T_{\rm eff}$=7000K, $\log g$=3.5 and $v\sin i$=15.4kms$^{-1}$ (no errors available). The difference of 300K in $T_{\rm eff}$ is not significant within the errors, and the $\log g$ and $v \sin i$ values are in good agreement with our results.

It is useful to compare the values of $T_{\rm eff}$ derived spectroscopically with those obtained via photometric methods (IRFM, (V - K) calibration, KIC). Inspection of Fig. \[confrTeff\], which illustrates such a comparison, shows a general good agreement among all these values. Quantitatively, a weighted mean of such differences gives: $T_{\rm eff}^{\rm  Spec}-T_{\rm eff}^{\rm IRFM}$=$-$200$\pm$200; $T_{\rm eff}^{\rm Spec}-T_{\rm eff}^{\rm (V-K)}$=$-$130$\pm$200; $T_{\rm eff}^{\rm Spec}-T_{\rm eff}^{\rm KIC}$=$-$50$\pm$300, non significant to the 1$\sigma$ level. Similarly a very good agreement is found between $T_{\rm eff}^{\rm Spec}$ and $T_{\rm eff}$ estimated through $uvby\beta$ photometry (see Table \[tab2\]). However there are two exceptions to this trend:

[*KIC05724440 (HD187234) -*]{} This star shows a large difference between the spectroscopic T$_{\rm eff}$ and that estimated from [*uvby$\beta$*]{} photometry (800$\pm$300K). This difference is at a level of $\approx$2.9$\sigma$, and deserves some comments. Indeed, there is no a clear explanation for such a large difference. The Loiano and INAF-OACT spectra give exactly the same values for $T_{\rm eff}$ and $\log g$, suggesting that there could be a problem with the photometry. The $uvby$ values reported for this star by @hauck are the average of the measurements by @olsen and @jordi, while the $\beta$ value, on which the $T_{\rm eff}$ depends, was measured only by the latter authors. The two quoted $uvby$ values are slightly discrepant, but the difference is not large enough to change significantly the derived value of $\log g$. We also considered the possibility that a close companion is affecting the photometric measurements. We visually inspected both [*POSS II*]{} and [*2MASS*]{} images of KIC05724440 (HD187234), where the star appears to be isolated in the near infrared. In the optical it is surrounded by a few very close faint stars whose contribution can hardly be considered significant. By using the calibration by @masana06, the discrepancy is reduced to only 350K, reinforcing our suspicion that there is something wrong with the $uvby\beta$ photometry of this star.

[*KIC08583770 (HD189177) -*]{} The $T_{\rm eff}$=9000$\pm$200 K derived spectroscopically for this star is in good agreement with the value derived from IRFM, and consistent within the errors with the $T_{\rm eff}$ derived from $(V-K)$ color. However there is a large discrepancy with respect to the KIC estimate. This occurrence could perhaps be explained in terms of a visual binary, with a companion star dimmer by 3 mag at a distance of 0.9 arcsec. Even if nothing is known about the companion, due to the small separation, it is likely that the photometric values are affected by the secondary star flux.

[lrcc]{} KIC &Luminosity & Mass Can. & Mass NonCan.\
&$L$/L$_{\odot}$ & $M$/M$_{\odot}$ & $M$/M$_{\odot}$\
03219256 & 19.0$^{+2.9}_{-2.5}$ & 2.20$^{+0.20}_{-0.15}$ & 2.20$^{+0.10}_{-0.10}$\
03429637 & 20.0$^{+6.0}_{-6.0}$ & 3.6$^{+0.70}_{-0.60}$ & 3.2$^{+0.60}_{-0.50}$\
03437940 & 12.5$^{+4.0}_{-3,9}$ & 1.80$^{+0.30}_{-0.20}$ & 1.80$^{+0.20}_{-0.10}$\
04570326 & 7.8$^{+3.7}_{-3.6}$ & 1.70$^{+0.20}_{-0.20}$ & 1.65$^{+0.30}_{-0.15}$\
05296877 & 7.9$^{+2.6}_{-2.6}$ & 1.60$^{+0.40}_{-0.20}$ & 1.70$^{+0.25}_{-0.30}$\
05724440 & 17.0$^{+4.4}_{-4.3}$ & 2.20$^{+0.60}_{-0.40}$ & 2.30$^{+0.30}_{-0.30}$\
05965837 & 7.4$^{+5.0}_{-4.3}$ & 1.70$^{+0.30}_{-0.20}$ & 1.65$^{+0.35}_{-0.15}$\
05988140 & 16.3$^{+4.7}_{-4.6}$ & 2.00$^{+0.60}_{-0.40}$ & 2.20$^{+0.30}_{-0.30}$\
07119530 & 18.8$^{+5.4}_{-5.4}$ & 2.20$^{+0.60}_{-0.40}$ & 2.40$^{+0.40}_{-0.40}$\
07798339 & 9.0$^{+2.9}_{-2.8}$ & 1.80$^{+0.30}_{-0.20}$ & 1.90$^{+0.25}_{-0.30}$\
08197788 & 12.7$^{+4.9}_{-4.8}$ & 1.85$^{+0.45}_{-0.15}$ & 1.80$^{+0.40}_{-0.20}$\
08264404 & 17.4$^{+5.5}_{-5.2}$ & 2.30$^{+0.60}_{-0.45}$ & 2.20$^{+0.50}_{-0.40}$\
08264698 & 14.3$^{+3.8}_{-3.6}$ & 2.00$^{+0.30}_{-0.15}$ & 1.90$^{+0.30}_{-0.20}$\
08583770 & 65.0$^{+19.0}_{-19.0}$ & 4.80$^{+1.00}_{-0.80}$ & 4.40$^{+0.80}_{-0.60}$\
09655114 & 13.5$^{+4.7}_{-4.7}$ & 1.90$^{+0.30}_{-0.30}$ & 1.90$^{+0.40}_{-0.30}$\
09775454 & 8.5$^{+3.8}_{-3.8}$ & 1.70$^{+0.20}_{-0.20}$ & 1.65$^{+0.30}_{-0.15}$\
11402951 & 15.5$^{+2.4}_{-2.7}$ & 2.30$^{+0.20}_{-0.30}$ & 2.20$^{+0.10}_{-0.10}$\
11445913 & 16.3$^{+3.2}_{-3.3}$ & 1.95$^{+0.30}_{-0.10}$ & 2.20$^{+0.10}_{-0.10}$\
11973705 & 8.6$^{+4.2}_{-4.9}$ & 1.60$^{+0.30}_{-0.10}$ & 1.60$^{+0.30}_{-0.15}$\

\[tab3\]

![image](hrgcan.ps){width="8cm"} ![image](hrgnoncan.ps){width="8cm"}

The HR and $\log \MakeLowercase{g} - \log  T_{\rm eff}$ diagrams {#hrd}
================================================================

The stellar parameters $\log g$ and $\log T_{\rm eff}$ determined in the previous section allow us to estimate the luminosity of the investigated objects by interpolating the tables by @schmidt. The result is reported in Table \[tab3\]. Note that the errors on the luminosity were evaluated through the same tables by taking into account the errors on $\log g$ and $\log T_{\rm eff}$. Figure\[hrdiagr\] shows the HR diagram for the nineteen stars studied in this work, in comparison with the zero-age main sequence (ZAMS) [@pickles], the observed instability strip for $\delta$Sct stars [@breger98] as well as the empirical and theoretical red edge of the $\gamma$Dor instability strip [@handler; @guzik]. We note that the pulsating variables (see Section \[kepler\]) are in the expected position, i.e. inside the instability strip, except for KIC08583770 (HD189177) and KIC05296877 (HAT199-27597) which are hotter and cooler than the instability strip, respectively. The former was discussed in the previous section, the latter is not a pulsating star (see Section \[kepler\]).

We can use the values of $\log g$ and $\log T_{\rm eff}$ to estimate the mass of the target stars. For this purpose we used the evolutionary tracks in the [ *BaSTI*]{} database[^10] which are based on the <span style="font-variant:small-caps;">franec</span> evolutionary code [@chieffi]. We retrieved tracks with both canonical and non-canonical (i.e. with convective overshooting: $\lambda_{OV}=0.2H_p$) physics in the mass range $1 - 6$M$_{\odot}$ with $[M/H]= 0.058$, $Z= 0.0198$, $Y= 0.273$, and mixing lenght=1.913 [@pietri04]. In Fig. \[fig3\] we show the $\log g - \log T_{\rm eff}$ diagram. The left and right panels in the figure show canonical and non-canonical tracks, respectively. The resulting masses for the two cases (listed in Table\[tab3\]) are very similar and agree well within 1$\sigma$. On other hand, $\delta$Sct stars are typically fast-rotating objects, and the rotation effects on the structure and evolution might modify the estimates of global parameters of the stars [see e.g. @goupil05; @suarez05; @fox06]. To verify if this effect is important in our case, we considered a typical case for a star with mass 1.7-1.8 M. According to @suarez05, even in case of v$\sin$i$\sim$150-200 km/s, the effect on the mass estimate from the HR diagram is of few %, well within the uncertainty due to the errors on the empirical estimates of luminosity and effective temperature (see table \[tab3\]).

[lccr]{} KIC & $\pi$(mas) & $L$/L$_{\odot}$ & $L$/L$_{\odot}$\
& & Hipp. & Spect.\
03429637 (HD178875) & 3.75$\pm$0.58 & 56.2$^{+26.3}_{-18.0}$ &20.0$^{+6.0}_{-6.0}$\
05724440 (HD187234) & 8.02$\pm$0.51 & 11.1$^{+2.1}_{-1.8}$ &17.0$^{+4.3}_{-4.3}$\
07798339 (HD173109) & 6.86$\pm$0.48 & 13.4$^{+2.8}_{-2.3}$ & 9.0$^{+2.9}_{-2.8}$\
11402951 (HD183489) & 5.91$\pm$0.63 & 14.9$^{+4.4}_{-3.4}$ &15.5$^{+2.4}_{-2.7}$\
Star & D (pc) & $L$/L$_{\odot}$ & $L$/L$_{\odot}$\
& &Cluster & Spect.\
08197788 (NGC6866-V1) & 1200$\pm$120 & 10.3$^{+3.3}_{-2.5}$ & 12.7$^{+5.0}_{-4.8}$\
08264404 (NGC6866-V3) & 1200$\pm$120 & 20.6$^{+6.5}_{-5.0}$ & 17.4$^{+5.5}_{-5.2}$\
08264698 (NGC6866-V2) & 1200$\pm$120 & 17.9$^{+5.7}_{-4.4}$ & 14.3$^{+3.8}_{-3.6}$\
09655114 (NGC6811-RH35) & 1030$\pm$50 & 17.2 $^{+5.9}_{-4.4}$ & 13.5$^{+4.7}_{-4.7}$\

\[tab4\]

Checks of the results by means of Parallaxes and Cluster stars
==============================================================

We used the parallaxes measured by the HIPPARCOS satellite [@perryman97] to verify the luminosities derived in the present work. We also estimated independently the luminosity of cluster stars by adopting the distances found in the literature obtained through e.g. isochrone fitting.

Only four stars in our sample are sufficiently bright for inclusion in the HIPPARCOS parallax catalogue. These are listed in Table\[tab4\] together with the parallaxes from the @leeuwen revised catalogue. To derive the luminosity we used the $V$ and $E(B-V)$ values listed in Table\[tab1\] as well as the bolometric correction as a function of spectral type from @pickles. The resulting luminosities and errors are listed in Table\[tab4\] where our spectroscopic results are also shown for comparison purposes. An inspection of the table reveals that there is agreement within the errors. The only obvious discrepancy is found for the star KIC03429637 (HD178875). The difference in luminosity is $> 1\,\sigma$, and deserves some discussion. We did not find any significant difference between the spectroscopic and the photometric estimates of $T_{\rm eff}$ for this star. Furthermore, the HIPPARCOS parallax [@leeuwen] is very small relative to the parallax estimated from its spectral type and apparent magnitude. In our opinion, KIC03429637 (HD178875) is very likely a double star [@dommanget94]. The binary nature can significantly affect the estimated parallax, colour, and $T_{\rm eff}$. As mentioned in Section \[parameter\], our spectroscopic determination of $T_{\rm eff}$ is in agreement with that derived by @abt.

As for cluster stars, we have to estimate the distances to the host clusters NGC 6866 and NGC 6811 first. as reported by @molenda, both the distance modulus and E(B-V) vary significantly from author to author. Here we decided to assume a distance D=1200$\pm$120 pc as in @molenda (no error on distance is available in the literature, we assumed conservatively an uncertainty of 10%). As for the reddening we adopted $E(B-V)=0.12\pm0.02$, according to @dutra who made a study of the foreground and background dust in the direction of the cluster. The resulting luminosities for the three variables in NGC 6866 are shown in Table \[tab4\] in comparison with our estimates. The agreement is good within the errors. distance modulus and $E(B-V)$ of this cluster were measured by @Glushkova and @luo. They found $DM=10.42\pm0.03$, $E(B-V)$=0.12$\pm$0.02, and $DM=10.59\pm0.09$, $E(B-V)$=0.12$\pm$0.05, respectively. To estimate the distance, we made a weighted mean of these results, obtaining D=1030$\pm$50 pc. Then, we calculated the luminosity for the star KIC09655114 (NGC6811-RH35) which is reported in the last row of Table \[tab4\]. Again, we note the good agreement within the errors with the spectroscopic result.

![image](per.ps)

[*Kepler*]{} observations {#kepler}
=========================

Information on [*Kepler*]{} observations for the stars studied here is given in Table\[tab:kepler\]. For 15 out of 19 stars short cadence observations are available. From these data we calculated the periodograms (by using L. Balona’s custom software, based on a combination of FFT and normal periodogram) shown in Fig. \[fig:per1\]. We note that practically all stars show peaks in both the low-frequency ($\gamma$Dor; gmode) and high-frequency ($\delta$Sct; pmode) regions. In this sense, practically all $\delta$Sct stars observed by [*Kepler*]{} are hybrids. This is a surprising finding which has been discussed in @griga10. To make a distinction, we followed the classification scheme proposed by latter author. We visually classified the stars as $\delta$Sct if most of the peaks are in the $\delta$Sct region and as $\delta$Sct – $\gamma$Dor if most of the peaks are in the $\delta$Sct region but with a significant contribution from the $\gamma$Dor region. The frequency 5c/d was taken as the boundary between the two regions. Following similar arguments, we classify a star as $\gamma$Dor or $\gamma$Dor – $\delta$Sct. There appears to be physical significance to such a scheme, as discussed by @griga10. We applied these classification criteria to the stars of this study, and classified six targets as $\delta$Sct stars, five stars as $\delta$Sct-$\gamma$Dor hybrids, four stars as $\gamma$Dor-$\delta$Sct hybrids, and three stars as pure $\gamma$Dor pulsators (see also Table 5). Below we discuss the targets that show particularities in their periodogram (Fig. \[fig:per1\]).

[*KIC03429637 (HD178875)*]{}: As noted above, this star shows a $> 1\,\sigma$ difference between the luminosity values derived from the HIPPARCOS parallax and from spectroscopy (see Table\[tab4\]). Binarity is a possible explanation for this discrepancy. The frequency spectrum shows two dominant peaks near 10 and 12 d-1. A model in terms of $\delta$Sct pulsations, rotation and/or binarity needs to be investigated.

[*KIC05296877 (HAT199-27597)*]{}: This star is the coolest star in the sample and lies outside the instability strip. The periodogram shows a single strong peak at $f = 5.302$c/d. KIC5296877 is probably a contact binary with an orbital period of $2/f = 0.38$d. The late spectral type of F4.5IV and the large value $v \sin i = 200$kms$^{-1}$ suggest that it is a high amplitude ellipsoidal variable.

[*KIC07119530 (HD183787)*]{}: this star has been classified as pure $\gamma$ Dor as the frequencies are predominantly in the $\gamma$ Dor range and those in the $\delta$ Sct region have low amplitude. However the star lies in the middle of the $\delta$ Sct instability strip. All the temperature indicators adopted in this paper agree very well one each other and indicate a $T_{\rm eff}>$7500 K, i.e. a bit too hot for a pure $\gamma$ Dor variable. We conclude that the variability classification of this star is uncertain since it could be a $\gamma$ Dor – $\delta$ Sct Hybrid.

[*KIC08583770 (HD189177)*]{}: This star is the hottest star in the group, and lies outside the instability strip (see Fig \[fig3\]). The periodogram shows significant power at very low frequency. The light curve of KIC08583770 is presented in Fig.\[fig:Kep\]. No specific period can be deduced, but it is clear that there is something peculiar about this star, which needs further investigation.

[*KIC09775454 (HD185115)*]{}: The frequency spectrum of KIC09775454 shows one dominant peak in the $\delta$Sct region, and several - seemingly equidistant - peaks at lower frequencies. Further investigation of the [*Kepler*]{} light curves will clarify if this star is a $\delta$Sct star with rotational modulation effects.

[*KIC11973705 (HD234999)*]{}: The light curves of KIC11973705 show a periodic long-term behaviour, with $P \approx 4$d (Fig. \[fig:Kep\]). The spectral type B9, recorded in the Henry Draper catalogue, is a full spectral class too early compared to our classification of A9.5V. It is most likely a $\delta$Sct star in a binary system.

[lcrrr]{} KIC ID & Type & N & Cad & $\Delta t$ (d)\
03219256 & $\delta$Sct & 43974 & SC & 30.03\
03429637 & $\delta$Sct & 9870 & LC & 217.98\
03437940 & $\delta$Sct & 43989 & SC & 30.03\
04570326 & $\gamma$Dor– $\delta$Sct & 44010 & SC & 29.97\
05296877 & - & 14245 & SC & 9.72\
05724440 & $\delta$Sct & 43093 & SC & 30.34\
05965837 & $\gamma$Dor & 14204 & SC & 9.70\
05988140 & $\delta$Sct - $\gamma$Dor & 2099 & LC & 44.44\
07119530 & $\gamma$Dor & 10340 & LC & 228.95\
07798339 & $\gamma$Dor & 43254 & SC & 29.97\
08197788 & $\gamma$Dor – $\delta$Sct & 43370 & SC & 29.97\
08264404 & $\delta$Sct – $\gamma$Dor & 43375 & SC & 29.97\
08264698 & $\gamma$Dor – $\delta$Sct & 43348 & SC & 29.97\
08583770 & $\delta$Sct – $\gamma$Dor & 41807 & SC & 30.79\
09655114 & $\delta$Sct & 38340 & SC & 27.11\
09775454 & $\delta$Sct – $\gamma$Dor & 10341 & LC & 228.95\
11402951 & $\delta$Sct & 14240 & SC & 9.72\
11445913 & $\delta$Sct – $\gamma$Dor & 14244 & SC & 9.72\
11973705 & $\gamma$Dor – $\delta$Sct & 14212 & SC & 9.72\

\[tab:kepler\]

Summary {#concl}
=======

We presented a spectroscopic analysis of 19 candidate $\delta$Sct variables observed by [*Kepler*]{} both in long and short cadence mode. The analysis is based on medium- to high-resolution spectra obtained at the Loiano and INAF-OACT observatories. For each star we derived $T_{\rm eff}$, $\log g$ and $v\sin i$ by matching the observed spectra with synthetic spectra computed from the [*SYNTHE*]{} code [@kur81] and using the LTE atmospheric models calculated by ATLAS9 [@kur93]. The typical errors are about 200K, 0.2dex, and 10 kms$^{-1}$ for $T_{\rm eff}$, $\log g$, and $v 
\sin i$, respectively. Equivalent spectral types and luminosity classes were also derived. The luminosities of the stars were obtained using the tables of @schmidt.

![Top panel: light curve of K8583770 (HD189177). Bottom panel: light curve of K11973705 (HD234999). The time is expressed in days starting from HJD=2454950.5 and the brightness is given in mmag.[]{data-label="fig:Kep"}](lc.ps){width="8cm"}

For ten stars we used Strömgren photometry from the literature to estimate the reddening. For seven stars for which $\beta$ photometry was also available, $T_{\rm eff}$ and $\log g$ could be obtained for comparison with our spectroscopic values. In addition, $V-K$ colours, the IFRM method and values listed in the KIC were used to obtain independent estimates of $T_{\rm eff}$. We find a general good agreement between photometric and spectroscopic results. Four stars with significant parallaxes and four cluster member objects were used to check our estimate of the luminosities. We obtain consistent results for all the stars, with the exception of KIC03429637 (HD178875), which is a wide binary and may have an erroneus parallax determination. Moreover, for KIC05724440 (HD187234) we suspect a problem with the $uvby\beta$ photometry, since $T_{\rm eff}$ derived from the $V-K$ index is in agreement with our estimate within the errors.

Finally, we present the periodograms for the 19 investigated stars, based on the [*Kepler*]{} satellite photometry. These beautiful data allowed us to classify the type of variability of each star, including KIC05296877, which is a high amplitude ellipsoidal variable candidate. As a result, we find six pure $\delta$ Sct, 3 pure $\gamma$ Dor and nine hybrid pulsators. This classification is consistent with the derived physical parameters and their position in the HR diagram. As already noted by @griga10, we were surprised by the large number of hybrid pulsators. An asteroseismic study of these objects will have a strong impact on our knowledge of the evolution and internal structure of A/F stars. A more in depth study of the pulsational behaviour of the 18 pulsators is out of the scope of this paper, and will be presented in a forthcoming paper.

The stellar parameter estimates for the 18 investigated pulsating stars, presented in this work, will be a fundamental starting point for building proper asteroseismic models aimed at interpreting the frequency spectra extracted from the exceptionally good [*Kepler*]{} data.

Acknowledgments {#acknowledgments .unnumbered}
===============

This work was supported by the Italian ESS project, contract ASI/INAF I/015/07/0, WP 03170 and by the European Helio- and Asteroseismology Network (HELAS), a major international collaboration funded by the European Commission’s Sixth Framework Programme.\
Funding for the Kepler mission is provided by NASA’s Science Mission Directorate. We thank the entire Kepler team for the development and operations of this outstanding mission.\
This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. This work has made use of BaSTI web tools. RSz. has been supported by the National Office for Reseach and Technology through the Hungarian Space Office Grant No. URK09350 and the ‘Lendület’ program of the Hungarian Academy of Sciences. MJPFGM and AG are co-supported by project PTDC/CTE-AST/098754/2008 from FCT-Portugal.

[99]{}

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[^1]: E-mail: <PRESIDIO_ANONYMIZED_EMAIL_ADDRESS>

[^2]: This work is based on spectra taken at the Loiano (INAF-OA Bologna) and Serra La Nave (INAF-OA Catania) Observatories.

[^3]: http://kepler.nasa.gov/

[^4]: http://www.bo.astro.it/loiano/index.htm

[^5]: REOSC is the Optical Department of the SAGEM Group.

[^6]: IRAF is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc.

[^7]: accessible via http://archive.stsci.edu/kepler/kepler\_fov/search.php

[^8]: Note, however, that only 25% of the KIC stars have $z^{'}$ photometry, and less than 0.1% have $u^{'}$ (see http://nsted.ipac.caltech.edu/data/NStED/kic\_columns.html)

[^9]: KIC05296877 (HAT199-27597) and the three objects in NGC 6866 have no spectral type known before.

[^10]: http://albione.oa-teramo.inaf.it/