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]


---
author:
- 'V.G. Klochkova'
title: 'Detection of heavy-metal lines in the spectrum of the circumstellar envelope of a post-AGB star'
---

=-1.4cm =-1.5cm

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

The cool variable star V354Lac=HD235858 identified with the infrared source IRAS22272+5435 is one of the most interesting candidates for protoplanetary ne-bulae (PPN). Intermediate-mass stars that evolve from the asymptotic giant branch (AGB) to a planetary nebula are observed at the short PPN phase of evolution. The initial masses of these stars lie within the range 3–8${\mathcal M}_{\odot}$. The evolution of intermediate-mass stars was described in detail, for example, by Blocker (2001), while we will recall only the main points of this process. Having passed through the successive core hydrogen and helium burning phases of evolution, these stars underwent great mass loss in the form of a strong stellar wind at the AGB phase (the mass loss rate reached 10$^{-4}{\mathcal M}_{\odot}/$yr). Since the bulk of the stellar mass is lost, a post-AGB star is a degenerate carbon–oxygen core with a typical mass of about 0.6${\mathcal M}_{\odot}$ surrounded by an expanding gas–dust envelope. The interest of astronomers in PPN stems, first, from the possibility of studying the history of mass loss via a stellar wind and, second, from the unique opportunity to observe the result of stellar nucleosynthesis, mixing, and dredge-up of nuclear-reaction products to the surface layers during the preceding evolution of the star.

V354Lac was one of the first PPN candidates with feature at 21$\mu$ in the infrared spectrum whose atmospheres exhibited large overabundances of carbon and s–process elements (Zacs [*et al.*]{} 1995). The energy distribution of V354Lac has a double-peak pattern typical of PPN, with the total energies emitted by the star in the visible wavelength range and by the circumstellar envelope in the infrared being almost identical (see Fig.4 in Hrivnak & Kwok (1991)). In the group of related objects, V354Lac stands out by significant photometric variability. According to Hrivnak and Kwok (1991), the B and V magnitudes for two epochs of observations differed by 0$\lefteqn{.}^{\rm m}$72 and 0$\lefteqn{.}^{\rm
m}$84, respectively.

Secular variability of the main parameters detected in several PPN stimulates a spectroscopic monitoring of the most probable PPN candidates. For example, we detected spectroscopic variability of the optical counterparts of the sources IRAS01005+7910 (Klochkova [*et al.*]{} 2002a), IRAS05040+4820 (Klochkova [*et al.*]{} 2004a), and IRAS20572+4919 (Klochkova [*et al.*]{} 2008) and found a trend in the effective temperature T$_{\rm eff}$ for the star HD161796=IRAS17436+5003 (Klochkova [*et al.*]{} 2002b). Here, it is also pertinent to recall the evolution of the parameters and chemical composition of the famous highly evolved star FGSge observed for more than a century (see the review by Jeffery and Schonberner (2006) and references therein). In this paper, we present the results of high spectral resolution observations of V354Lac for the epoch 2007–2008 and compare the new data with previous ones. Our main goal is to reveal probable spectroscopic variability and peculiarity of the spectrum as well as to study the velocity field in the atmosphere and circumstellar envelope of the star.

Observations and spectroscopic data reduction
=============================================

We obtained new spectroscopic data for V354Lac with the NES echelle spectrograph (Panchuk [*et al.*]{} 2007) at the Nasmyth focus of the 6-m telescope BTA of the Special Astrophysical Observatory. The observations were performed with a large-size 2048$\times$2048-pixel CCD array and an image slicer (Panchuk [*et al.*]{} 2007). The spectral resolution was R=60000. The first spectrum (JD=2454170.58) was taken in the wavelength range 4514–5940Å, the next two spectra (JD=2454225.51 and 2454727.35) were taken in the longer wavelength range, 5215–6690 and 5260–6760 A, respectively. One-dimensional spectra were extracted from two-dimensional echelle frames using the ECHELLE context of the MIDAS software package modified by Yushkin & Klochkova (2005). Cosmic-ray particle hits were removed by a median averaging of two successive spectra. The wavelength calibration was performed using the spectra of a hollow-cathode Th–Ar lamp. The heliocentric radial velocities V$_{\odot}$ estimated from these spectra and listed below in the table were found using the DECH20 package (Galazutdinov 1992).

Discussion of results
=====================

Peculiarity of the Spectrum
---------------------------

Hrivnak (1995) classified V354Lac as a G5Iap supergiant. The main features of its optical spectrum were pointed out even in the firrst works with a low spectral resolution. Hrivnak (1995) and Hrivnak & Kwok (1991) found that, compared to the spectrum of a normal supergiant with a similar temperature, the spectrum of V354Lac exhibits a weaker H$\delta$ line, stronger BaII lines, and CN, C$_2$ and C$_3$ molecular absorption bands. Most of the listed features are also observed in our 2007–2008 spectra. In particular, we used rotational lines of the Swan C$_2$(0;0) band, with the head at 5165.2Å, to determine the expansion velocity of the envelope (for more detail, see below).

The low-excitation BaII lines are the strongest absorption features in the spectrum of V354Lac; their equivalent widths W$_{\lambda}$ exceed 0.6Å. The absorption features of other ions of s-process elements (La, Ce) are equally strong; their W$_{\lambda}>$0.3Å. Figure1 shows the H$\alpha$ line profile that consists of an absorption component with a narrow core and broad wings for JD=2454225.5. As we see from the figure, the observed H$\alpha$ line profile in the spectrum of V354Lac agrees with the theoretical one calculated with its fundamental parameters T$_{\rm eff}$=5650 K, $\log g$=0.2, $\xi_t$=5.0km$/$s, and the elemental abundances derived by Klochkova [*et al.*]{} (2009). Thus, we found no weakening of this line, as expected from the results of Hrivnak (1995). This is indicative of the line formation in the stellar photosphere and a weak contribution from the envelope. The positions of the H$\alpha$ and H$\delta$ cores differ by 2–4km$/$s from the averaged velocity measured from photospheric metal lines.

The high spectral resolution allowed us to detect another, previously unobservable feature of the optical spectrum for V354Lac — splitting of the cores of the strongest heavy-metal lines. This splitting is clearly seen from Fig.2 for the profile of the BaII$\lambda$6141Å line with an equivalent width W$_{\lambda}\approx$1Å. Such splitting (or asymmetry of the line profile due to the extended blue wing) is also observed for other BaII lines ($\lambda$ 5435, 5853, and 6496Å) and for such strong lines as YII5402Å, LaII6390Å, and NdII5234Å and 5293Å. The lines of these heavy elements in the spectrum of V354Lac are enhanced to an extent that their intensities are comparable to those of HI lines (compare Fig.1 and 2). Asymmetry is clearly seen, for example, in the BaII5853 line profile (Fig.3). This figure, which shows the BaII5853 and 6141Å lines for several dates of observations, also illustrates variability of the profiles of strong lines. Unfortunately, the BaII6141Å line was recorded only for two dates, but the profiles may be said to be variable even in this case.

All of the lines with detected core splitting (or profile asymmetry) are distinguished by low lower-level excitation potentials, $\chi_{\rm low}
<$1eV. Obviously, the strong low-excitation lines originating in the upper layers of the stellar atmosphere are affected by the gas envelope. As an illustration, Fig.4 compares the BaII and LaII lines in the spectrum taken on one date (JD=2454225.51).

As an example, let us consider the picture of core splitting for heavy-element lines in more detail for the BaII6141Å line, for which this effect is most pronounced. The separation between the absorption components of the BaII6141Å line is about 35km$/$s. The short-wavelength component coincides in position with the circumstellar component of the NaD1 profile (see Fig.5). This coincidence confirms that, apart from the photospheric component, the complex BaII6141Å line profile contains a component originating in the circumstellar envelope. At an insuficient spectral resolution, the intensity of the envelope components is added to the intensity of the components originating in the atmosphere. As follows from Zacs [*et al.*]{} (1995), Reddy [*et al.*]{} (2002), and Klochkova [*et al.*]{} (2009), large overabundances of heavy elements synthesized during the s-process are observed in the atmosphere of V354Lac. Because of core splitting (and/or asymmetry), the heavy-element abundances derived from strong absorption lines in the spectrum of V354Lac turn out to be overestimated by about 0.2–0.4dex at an unsufficient spectral resolution.

The abundances derived from moderate-intensity lines will be more realistic. We emphasize that such a complex profile, which, apart from the photospheric and interstellar components, also contains the circumstellar component, has been previously observed only for the NaID doublet lines. In particular, this is also true for the star V354Lac under study. Reddy [*et al.*]{} (2002) distinguished the circumstellar component in the NaID lines. The circumstellar absorption features of the NaID lines were also identified in the spectrum of the well-studied post-AGB star HD56126 (Bakker [*et al.*]{} 1996; Klochkova & Chentsov 2007). In addition, manifestations of the gas–dust circumstellar envelope in the form of emission components in the NaID lines are known. As an example, we present the spectra of the protoplanetary nebula V510Pup identified with the infrared source IRAS08005$-$2356 (Klochkova & Chentsov, 2004), the two-lobe nebula Egg=AFGL2688 (Klochkova [*et al.*]{} 2004b), and the semiregular variable QYSge=IRAS20056+1834 (Rao [*et al.*]{} 2002; Klochkova [*et al.*]{} 2007c). In our study, we have found a manifestation of the envelope in heavy-metal lines for the first time.

Radial velocities
-----------------

[**Metal lines.**]{} To determine the mean heliocentic radial velocity V$_\odot$, we measured the positions of a large number (about 300) of minimally blended absorption lines in the spectra of V354Lac. The lines were selected using a spectral atlas for the post-AGB star HD56126, which may be considered as a canonical post-AGB object (Klochkova [*et al.*]{} 2007a). The atlas was compiled by Klochkova [*et al.*]{} (2007b) from echelle spectra taken with the same NES spectrograph of the 6-m telescope. The blending level in the spectrum of V354Lac is higher than that in the spectrum of HD56126 because of the later spectral type of the star (the effective temperature of HD56126, T$_{\rm eff}= 7000$K, was determined by Klochkova (1995)) and because of the splitting and asymmetry of many lines. Due to enhanced blending, the accuracy of measuring V$_{\odot}$ using one line (rms deviation $\sigma$) is about 2 km$/$s from our 2007–2008 spectra. The radial velocities of V354Lac measured from the set of spectral features are listed in the table. Here, the second column gives the mean V measured from metal lines. The next columns give V$_{\odot}$ measured from the H$\alpha$ and H$\beta$ lines, the components of the NaD lines, and the rotational lines of the Swan C$_2$ molecular band.

In addition to the data on the 2007–2008 spectra, the table includes our measurements of V$_{\odot}$ based on a spectrum taken previously at BTA with the Lynx echelle spectrograph (Panchuk [*et al.*]{} 1999) with resolution R=25000. The last row gives the mean V$_{\odot}$ from Reddy [*et al.*]{} (2002). As follows from the longterm observations by Hrivnak and Lu (2000), the radial-velocity variability amplitude and period for V354Lac are typical of PPN: the radial velocity varies within the range ($-34 \div -41$)km$/$s with a period of 127$^{\rm d}$. All of the mean V$_{\odot}$ derived using metal absorption lines from the table lie within this range of variability.

  -------------------- --------- ------------------- --------- --------- -------------
              JD=24...                                                   
                       metals            HI                      C$_2$   
               \[3pt\]                               blue         red    
              48850.51 $-$38.2    $-$41.1 H$\alpha$  $-$50.2    $-$13.2  $-$50.5(8)
      \[3pt\] 54170.58 $-$40.1    $-$45.1 H$\beta$   $-$50.6    $-$14.4  $-$50.1(21)
      \[3pt\] 54225.51 $-$38.4    $-$37.2 H$\alpha$  $-$51.1    $-$13.4  
      \[3pt\] 54727.35 $-$38.0    $-$34.6 H$\alpha$  $-$51.6    $-$14.0  
    \[3pt\] 20.08.2000                                                   
               \[3pt\]                                                   
  -------------------- --------- ------------------- --------- --------- -------------

  : Heliocentric radial velocities V$_{\odot}$ for three epochs of observations measured from various spectral features. The number of measured lines is given in parentheses. The first row provides V$_{\odot}$ derived from the spectrum taken at BTA with the Lynx spectrograph (Panchuk [*et al.*]{} 1999, R=25000). The last row presents the data from Reddy [*et al.*]{} (2002)

[**Molecular spectrum.**]{} Apart from the infrared excess and reddening, the presence of a gas–envelope around the central star of PPN also manifests itself in features of the optical spectra. Since the molecular bands can be formed in the atmosphere of a star with a temperature T$_{\rm
eff}<3000$K, it is obvious that for a G5 star, the molecular bands are formed in the circumstellar envelope. Vibrational Swan C$_2$ molecular bands are observed in our spectra of V354Lac. The high spectral resolution makes it possible to measure accurately the positions of the rotational lines of the Swan (0;0) band. Using the rotational-line wavelengths from the electronic tables to the paper by Bakker [*et al.*]{} (1997), we measured the positions of 21 rotational lines of the Swan (0;0) band and determined the mean radial velocity in the band-formation region, V$_{\odot}(0;0)=-50.1 \pm 0.2$km$/$s. Because of their narrow profiles compared to the photospheric lines, the rotational lines of the Swan (0;0) band are easily distinguished in the spectrum. Therefore, the position of one line can be measured with an accuracy of about 0.8km$/$s, which is much better than that for photospheric absorption lines. Since the Swan (1;0) band in the short-wavelength part of the spectrum 4712–4734Å is strongly blended by photospheric lines, the measurement accuracy is much lower, V$_{\odot}(1;0)=-50.0\pm 1.0$km$/$s.

The shift of circumstellar features relative to the systemic velocity allows the expansion velocity of the corresponding envelope regions to be determined. Fong [*et al.*]{} (2006) derived the systemic velocity V$_{\rm
lsr}^{\rm sys}=-27.5$km$/$s (V$_{\odot}^{\rm lsr} =-39.7$km$/$s) of the source IRAS22272+5435 from the position of the center of the CO (1–0) profile. In contrast to the emission CO lines formed in an extended envelope that expands in all directions, the observed absorption lines of molecular carbon are formed in the part of the envelope located between the star and the observer. As a result, we obtain the velocity of the Swan-bands formation region relative to the stellar center, V$_{\rm
exp}$=10.8km$/$s. This value, which may be considered as the envelope expansion velocity derived from optical spectra, agrees well with the the expansion velocity for IRAS22272+5435, V$_{\rm exp}=10.8 \pm
1.1$km$/$s, from the catalog by Loup [*et al.*]{} (1993), who collected numerous observations of circumstellar envelopes in CO and HCN molecular bands. Note that the envelope-expansion velocity for IRAS22272+5435 is typical of the circumstellar envelopes of post-AGB stars (see, e.g., Loup [*et al.*]{} 1993).

The heliocentric systemic velocity V$_{\odot}^{\rm lsr} =-39.7$km$/$s agrees well with the mean velocity of the star inferred from metal lines. This agreement indicates that there is no secondary component in the system of IRAS22272+5435 or, to be more precise, there is no secondary component with a stellar mass. This is a nontrivial result, since the chemical evolution, mixing, and dredge-up of nuclear-reaction products to the surface layers of the stellar atmosphere, the outflow of matter, and the formation of envelope morphology can proceed in a special way in the presence of a secondary companion.

Taking into account the galactic CO velocity maps (Vallèe 2008), the galactic coordinates (l=103$\lefteqn{.}^{\rm o}$3, b=$-2\lefteqn{.}^{\rm o}$51), and the systemic velocity V$_{\rm
lsr}^{\rm sys}=-27.5$km$/$s of IRAS22272+5435, we can assume that the source is located between the local and Perseus arms.

[**NaD doublet.**]{} Both lines of the resonance NaI doublet in the spectrum of V354Lac have a complex structure. As follows from the table and Fig.5, which shows the D1 line profile, the doublet lines contain two strong absorption components whose positions correspond to the velocities V$_{\odot}$=$-50$ and $-13$km$/$s. Obviously, the line with V$_{\odot}$=$-50$km$/$s originates in the circumstellar envelope, where the circumstellar Swan C$_2$ molecular bands are also formed. The second component with (V$_{\odot}$=$-13$km$/$s) is interstellar in origin. The presence of this interstellar component, V$_{\rm lsr}
\approx-27$km$/$s, confirms our assumption that V354 Lac is located in the Galaxy farther than the local arm. According Georgelin and Georgelin (1970), the radial velocity in the local and Perseus spiral arms of the Galaxy are V$_{\rm lsr}\approx -10$km$/$s and $-55$km$/$s, respectively. Thus, the distance to the Perseus arm d=3.6kpc derived by Foster & MacWilliams (2006) may be used as an upper limit for the source. By modeling the bolometric flux from IRAS22272+5435, Loup [*et al.*]{} (1993) estimated the distance to the source to be d=2.35kpc.

As follows from Fig.5, the blue wings of the NaI absorption features hint at the presence of poorly resolvable components in our spectra: V$_{\odot}\approx -57$km$/$s (V$_{\rm lsr}\approx -70$km$/$s) and V$_{\odot}\approx -24$km$/$s (V$_{\rm lsr}\approx -37$km$/$s).

Conclusions {#conclusions .unnumbered}
===========

Based on the optical spectra of the post-AGB star V354 Lac taken in 2007–2008 with the echelle spectrograph of the 6-m telescope with spectral resolution R=60000, we detected core splitting or asymmetry (an extended blue wing) of absorption lines with lower-level excitation potentials $\chi_{\rm low}<$1eV. This primarily applies to the strongest absorption lines identified with heavy-metal (Ba, La, Ce, Nd) ion lines. Allowance for the detected core splitting of the strongest absorption lines reduces the heavy-metal overabundances revealed previously by 0.2–0.4 dex.

The observed H$\alpha$ line profile is in good agreement with the theoretical one calculated with the fundamental stellar parameters. This is indicative of the line formation in the stellar photosphere and a weak contribution from the envelope. The radial velocity of the star measured for two epochs of observations in 2007–2008 closely coincides, within the error limits, with the previously published data. This suggests that there are no velocity field variations in the atmosphere and circumstellar envelope of V354Lac over the last 15 years of observations.

Acknowledgments {#acknowledgments .unnumbered}
---------------

This work was supported by the Russian Foundation for Basic Research (project No.08–02–00072a), the “Extended objects in the Universe” Basic Research Program of the Division of Physical Sciences of the Russian Academy of Sciences, and the “Origin and Evolution of Stars and Galaxies” Program of the Presidium of the Russian Academy of Sciences.

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