bluuebunny/crossref_metadata_2025 huggingface dataset:
The Nearby Dwarf Irregular Galaxy IC 1613 and Its Complex Bubble Region: Chandra and VLA Observations
Authors: Schlegel E. M. , Lacey C. K. , Pannuti Thomas G. , Lozinskaya T. , Moiseev A.
Published: January 2022

We observed the nearby irregular galaxy IC 1613 with the Chandra X-ray Observatory, for 49.9 ks using the ACIS S3 chip, and with the VLA at 6 cm for 0.7 hr. The Chandra observation targeted the extensive bubble region in the northeast quadrant. We detect 31 sources within the D
25 diameter above a significance of 3σ corresponding to a point-source luminosity limit L
X of ≈2 × 1035 erg s−1 (0.3–8 keV band). The VLA observation covered the entire galaxy with an angular resolution of 5″. We detect 11 sources: five do not fall on the ACIS chips, four fall on the S3 CCD, and two sit on the edge of the S2 CCD. We also describe corresponding Spitzer IRAC and MIPS images. Our detected source list matches the lists of two previous global point-source analyses except at the faint end. With the exception of one bright supernova remnant, the sources appear to be low-luminosity stellar sources (e.g., RS CVn stars) or X-ray binaries, or background objects. We identify one candidate supersoft source. All but one of the sources have at least one optical or infrared counterpart; three sources have radio counterparts. We describe our search for diffuse emission from the bubble region. We assign an upper limit of ≈5 × 1035 erg s−1 on the integrated flux and ≈1.4 × 1030 erg s−1 pc−2 on the surface brightness emission in the 0.5–2 keV band from that region.
An Algorithm to Calibrate and Correct the Response to Unpolarized Radiation of the X-Ray Polarimeter Onboard IXPE
Authors: Rankin John , Muleri Fabio , Tennant Allyn F. , Bachetti Matteo , Costa Enrico , Marco Alessandro Di , Fabiani Sergio , La Monaca Fabio , Soffitta Paolo , Tobia Antonino , Trois Alessio , Xie Fei , Baldini Luca , Di Lalla Niccolò , Manfreda Alberto , O’Dell Stephen L. , Perri Matteo , Puccetti Simonetta , Ramsey Brian D. , Sgrò Carmelo , Weisskopf Martin C.
Published: January 2022

The Gas Pixel Detector (GPD) is an X-ray polarimeter to fly onboard IXPE and other missions. To correctly measure the source polarization, the response of IXPE’s GPDs to unpolarized radiation has to be calibrated and corrected. In this paper, we describe the way such response is measured with laboratory sources and the algorithm to apply such correction to the observations of celestial sources. The latter allows to correct the response to polarization of single photons, therefore allowing great flexibility in all the subsequent analysis. Our correction approach is tested against both monochromatic and nonmonochromatic laboratory sources and with simulations, finding that it correctly retrieves the polarization up to the statistical limits of the planned IXPE observations.
Photometric Classification of Early-time Supernova Light Curves with SCONE
Authors: Qu Helen , Sako Masao
Published: January 2022

In this work, we present classification results on early supernova light curves from SCONE, a photometric classifier that uses convolutional neural networks to categorize supernovae (SNe) by type using light-curve data. SCONE is able to identify SN types from light curves at any stage, from the night of initial alert to the end of their lifetimes. Simulated LSST SNe light curves were truncated at 0, 5, 15, 25, and 50 days after the trigger date and used to train Gaussian processes in wavelength and time space to produce wavelength–time heatmaps. SCONE uses these heatmaps to perform six-way classification between SN types Ia, II, Ibc, Ia-91bg, Iax, and SLSN-I. SCONE is able to perform classification with or without redshift, but we show that incorporating redshift information improves performance at each epoch. SCONE achieved 75% overall accuracy at the date of trigger (60% without redshift), and 89% accuracy 50 days after trigger (82% without redshift). SCONE was also tested on bright subsets of SNe (r < 20 mag) and produced 91% accuracy at the date of trigger (83% without redshift) and 95% five days after trigger (94.7% without redshift). SCONE is the first application of convolutional neural networks to the early-time photometric transient classification problem. All of the data processing and model code developed for this paper can be found in the SCONE software package
1

1

github.com/helenqu/scone

located at github.com/helenqu/scone (Qu 2021).
Dynamical Mass of the Exoplanet Host Star HR 8799
Authors: Sepulveda Aldo G. , Bowler Brendan P.
Published: January 2022

HR 8799 is a young A5/F0 star hosting four directly imaged giant planets at wide separations (∼16–78 au), which are undergoing orbital motion and have been continuously monitored with adaptive optics imaging since their discovery over a decade ago. We present a dynamical mass of HR 8799 using 130 epochs of relative astrometry of its planets, which include both published measurements and new medium-band 3.1 μm observations that we acquired with NIRC2 at Keck Observatory. For the purpose of measuring the host-star mass, each orbiting planet is treated as a massless particle and is fit with a Keplerian orbit using Markov chain Monte Carlo. We then use a Bayesian framework to combine each independent total mass measurement into a cumulative dynamical mass using all four planets. The dynamical mass of HR 8799 is

1.47

−
0.17

+
0.12

M
⊙ assuming a uniform stellar mass prior, or

1.46

−
0.15

+
0.11

M
⊙ with a weakly informative prior based on spectroscopy. There is a strong covariance between the planets’ eccentricities and the total system mass; when the constraint is limited to low-eccentricity solutions of e < 0.1, which are motivated by dynamical stability, our mass measurement improves to

1.43

−
0.07

+
0.06

M
⊙. Our dynamical mass and other fundamental measured parameters of HR 8799 together with Modules for Experiments in Stellar Astrophysics Isochrones and Stellar Tracks grids yields a bulk metallicity most consistent with [Fe/H] ∼ −0.25–0.00 dex and an age of 10–23 Myr for the system. This implies hot-start masses of 2.7–4.9 M
Jup for HR 8799 b and 4.1–7.0 M
Jup for HR 8799 c, d, and e, assuming they formed at the same time as the host star.
The Transit Timing and Atmosphere of Hot Jupiter HAT-P-37b
Authors: A-thano Napaporn , Jiang Ing-Guey , Awiphan Supachai , Rattanamala Ronnakrit , Su Li-Hsin , Hengpiya Torik , Sariya Devesh P. , Yeh Li-Chin , Shlyapnikov A. A. , Gorbachev Mark A. , Rublevski Alexey N. , Mannaday Vineet Kumar , Thakur Parijat , Sahu D. K. , Mkrtichian David , Griv Evgeny
Published: January 2022

We perform transit timing variation (TTV) and transmission spectroscopy analyses of the planet HAT-P-37b, which is a hot Jupiter orbiting a G-type star. Nine new transit light curves are obtained and analyzed together with 21 published light curves from the literature. The updated physical parameters of HAT-P-37b are presented. The TTV analyses show a possibility that the system has an additional planet that induced the TTVs amplitude signal of 1.74 ± 0.17 minutes. If the body is located near the 1:2 mean-motion resonance orbit, the sinusoidal TTV signal could be caused by the gravitational interaction of a sub-Earth-mass planet with mass of 0.06 M
⊕. From the analysis of an upper-mass limit for the second planet, a Saturn-mass planet with orbital period less than 6 days is excluded. The broadband transmission spectra of HAT-P-37b favors a cloudy atmospheric model with an outlier spectrum in the B filter.
IM Normae: The Death Spiral of a Cataclysmic Variable?
Authors: Patterson Joseph , Kemp Jonathan , Monard Berto , Myers Gordon , de Miguel Enrique , Hambsch Franz-Josef , Warhurst Paul , Rea Robert , Dvorak Shawn , Menzies Kenneth , Vanmunster Tonny , Roberts George , Campbell Tut , Starkey Donn , Ulowetz Joseph , Rock John , Seargeant Jim , Boardman James , Lemay Damien , Cejudo David , Knigge Christian
Published: January 2022

We present a study of the orbital light curves of the recurrent nova IM Normae since its 2002 outburst. The broad “eclipses” recur with a 2.46 hr period, which increases on a timescale of 1.28(16) × 106 yr. Under the assumption of conservative mass transfer, this suggests a rate near 10−7
M
⊙ yr−1, and this agrees with the estimated accretion rate of the postnova, based on our estimate of luminosity. IM Nor appears to be a close match to the famous recurrent nova T Pyxidis. Both stars appear to have very high accretion rates, sufficient to drive the recurrent-nova events. Both have quiescent light curves, which suggest strong heating of the low-mass secondary, and very wide orbital minima, which suggest obscuration of a large “corona” around the primary. And both have very rapid orbital period increases, as expected from a short-period binary with high mass transfer from the low-mass component. These two stars may represent a final stage of nova—and cataclysmic variable—evolution, in which irradiation-driven winds drive a high rate of mass transfer, thereby evaporating the donor star in a paroxysm of nova outbursts.
Searching for Gravitationally Lensed Gamma-Ray Bursts with Their Afterglows
Authors: Chen Shengnan , Wen Xudong , Gao He , Liao Kai , Liu Liangduan , Zhao Litao , Li Zhengxiang , Biesiada Marek , Piórkowska-Kurpas Aleksandra , Xiao Shuo , Xiong Shaolin
Published: January 2022

Gamma-ray bursts (GRBs) at high redshifts are expected to be gravitationally lensed by objects of different mass scales. Other than a single recent claim, no lensed GRB has been detected so far by using gamma-ray data only. In this paper, we suggest that multiband afterglow data might be an efficient way to search for lensed GRB events. Using the standard afterglow model, we calculate the characteristics of the lensed afterglow lightcurves under the assumption of two popular analytic lens models: the point-mass and singular isothermal sphere models. In particular, when different lensed images cannot be resolved, their signals would be superimposed together with a given time delay. In this case, the X-ray afterglows are likely to contain several X-ray flares of similar width in linear scale and similar spectrum, and the optical afterglow lightcurve will show re-brightening signatures. Since the lightcurves from the image arriving later would be compressed and deformed in the logarithmic timescale, the larger time delay (i.e., the larger mass of the lens), the easier it is to identify the lensing effect. We analyzed the archival data of optical afterglows and found one potential candidate of the lensed GRB (130831A) with time delay ∼500 s; however, observations of this event in gamma-ray and X-ray bands seem not to support the lensing hypothesis. In the future, with the cooperation of the all-sky monitoring gamma-ray detectors and multiband sky survey projects, the method proposed in this paper would be more efficient in searching for strongly lensed GRBs.
Galactic Chemical Evolution of Radioactive Isotopes with an s-process Contribution
Authors: Trueman Thomas C. L. , Côté Benoit , Yagüe López Andrés , den Hartogh Jacqueline , Pignatari Marco , Soós Benjámin , Karakas Amanda I. , Lugaro Maria
Published: January 2022

Analysis of inclusions in primitive meteorites reveals that several short-lived radionuclides (SLRs) with half-lives of 0.1–100 Myr existed in the early solar system (ESS). We investigate the ESS origin of 107Pd, 135Cs, and 182Hf, which are produced by slow neutron captures (the s-process) in asymptotic giant branch (AGB) stars. We modeled the Galactic abundances of these SLRs using the OMEGA+ galactic chemical evolution (GCE) code and two sets of mass- and metallicity-dependent AGB nucleosynthesis yields (Monash and FRUITY). Depending on the ratio of the mean-life τ of the SLR to the average length of time between the formations of AGB progenitors γ, we calculate timescales relevant for the birth of the Sun. If τ/γ ≳ 2, we predict self-consistent isolation times between 9 and 26 Myr by decaying the GCE predicted 107Pd/108Pd, 135Cs/133Cs, and 182Hf/180Hf ratios to their respective ESS ratios. The predicted 107Pd/182Hf ratio indicates that our GCE models are missing 9%–73% of 107Pd and 108Pd in the ESS. This missing component may have come from AGB stars of higher metallicity than those that contributed to the ESS in our GCE code. If τ/γ ≲ 0.3, we calculate instead the time (T
LE) from the last nucleosynthesis event that added the SLRs into the presolar matter to the formation of the oldest solids in the ESS. For the 2 M
⊙, Z = 0.01 Monash model we find a self-consistent solution of T
LE = 25.5 Myr.
Photodynamical Modeling of the Fascinating Eclipses in the Triple-star System KOI-126
Authors: Yenawine Mitchell E. , Welsh William F. , Orosz Jerome A. , Bieryla Allyson , Cochran William D. , Endl Michael , Latham David W. , Quinn Samuel N. , Short Donald R. , Windmiller Gur
Published: January 2022

We explore the fascinating eclipses and dynamics of the compact hierarchical triple-star system KOI-126 (KIC 5897826). This system is composed of a pair of M-dwarf stars (KOI-126 B and C) in a 1.74 day orbit that revolve around an F star (KOI-126 A) every 34 days. Complex eclipse shapes are created as the M stars transit the F star, due to two effects: (1) the duration of the eclipse is a significant fraction of the M-star orbital period, so the prograde or retrograde motion of the M stars in their orbit lead to unusually short or long duration eclipses; (2) due to 3-body dynamics, the M-star orbit precesses with an astonishingly quick timescale of 1.74 yr for the periastron (apsidal) precession, and 2.73 yr for the inclination and nodal angle precession. Using the full Kepler data set, supplemented with ground-based photometry, plus 29 radial velocity measurements that span 6 yr, our photodynamical modeling yields masses of M

A
= 1.2713 ± 0.0047 M
⊙ (0.37%), M

B
= 0.23529 ± 0.00062 M
⊙ (0.26%), and M

C
= 0.20739 ± 0.00055 M
⊙ (0.27%) and radii of R

A
= 1.9984 ± 0.0027 R
⊙ (0.14%), R

B
= 0.25504 ± 0.00076 R
⊙ (0.3%), and R

C
= 0.23196 ± 0.00069 R
⊙ (0.3%). We also estimate the apsidal motion constant of the M dwarfs, a parameter that characterizes the internal mass distribution. Although it is not particularly precise, we measure a mean apsidal motion constant,

k

2

¯

, of

0.046

−
0.028

+
0.046

, which is approximately 2σ lower than the theoretical model prediction of 0.150. We explore possible causes for this discrepancy.
CH3-Terminated Carbon Chains in the GOTHAM Survey of TMC-1: Evidence of Interstellar CH3C7N
Authors: Siebert Mark A. , Lee Kin Long Kelvin , Remijan Anthony J. , Burkhardt Andrew M. ,   The GOTHAM Collaboration, Loomis Ryan A. , McCarthy Michael C. , McGuire Brett A.
Published: January 2022

We report a systematic study of all known methyl carbon chains toward TMC-1 using the second data release of the GOTHAM survey, as well as a search for larger species. Using Markov Chain Monte Carlo simulations and spectral line stacking of over 30 rotational transitions, we report statistically significant emission from methylcyanotriacetylene (CH3C7N) at a confidence level of 4.6σ, and use it to derive a column density of ∼1011 cm−2. We also searched for the related species, methyltetraacetylene (CH3C8H), and place upper limits on the column density of this molecule. By carrying out the above statistical analyses for all other previously detected methyl-terminated carbon chains that have emission lines in our survey, we assess the abundances, excitation conditions, and formation chemistry of methylpolyynes (CH3C2n
H) and methylcyanopolyynes (CH3C2n-1N) in TMC-1, and compare those with predictions from a chemical model. Based on our observed trends in column density and relative populations of the A and E nuclear spin isomers, we find that the methylpolyyne and methylcyanopolyyne families exhibit stark differences from one another, pointing to separate interstellar formation pathways, which is confirmed through gas–grain chemical modeling with nautilus.
The Eccentric Nature of Eccentric Tidal Disruption Events
Authors: Cufari M. , Coughlin Eric R. , Nixon C. J.
Published: January 2022

Upon entering the tidal sphere of a supermassive black hole, a star is ripped apart by tides and transformed into a stream of debris. The ultimate fate of that debris, and the properties of the bright flare that is produced and observed, depends on a number of parameters, including the energy of the center of mass of the original star. Here we present the results of a set of smoothed particle hydrodynamics simulations in which a 1M
⊙, γ = 5/3 polytrope is disrupted by a 106
M
⊙ supermassive black hole. Each simulation has a pericenter distance of r
p = r
t (i.e., β ≡ r
t/r
p = 1 with r
t the tidal radius), and we vary the eccentricity e of the stellar orbit from e = 0.8 up to e = 1.20 and study the nature of the fallback of debris onto the black hole and the long-term fate of the unbound material. For simulations with eccentricities e ≲ 0.98, the fallback curve has a distinct, three-peak structure that is induced by self-gravity. For simulations with eccentricities e ≳ 1.06, the core of the disrupted star reforms following its initial disruption. Our results have implications for, e.g., tidal disruption events produced by supermassive black hole binaries.
Simultaneous High Dynamic Range Algorithm, Testing, and Instrument Simulation
Authors: Mason James Paul , Seaton Daniel B. , Jones Andrew R. , Jin Meng , Chamberlin Phillip C. , Sims Alan , Woods Thomas N.
Published: January 2022

Within an imaging instrument’s field of view, there may be many observational targets of interest. Similarly, within a spectrograph’s bandpass, there may be many emission lines of interest. The brightness of these targets and lines can be orders of magnitude different, which poses a challenge to instrument and mission design. A single exposure can saturate the bright emission and/or have a low signal-to-noise ratio (S/N) for faint emission. Traditional high dynamic range (HDR) techniques solve this problem by either combining multiple sequential exposures of varied duration or splitting the light to different sensors. These methods, however, can result in the loss of science capability, reduced observational efficiency, or increased complexity and cost. The simultaneous HDR method described in this paper avoids these issues by utilizing a special type of detector whose rows can be read independently to define zones that are then composited, resulting in areas with short or long exposure measured simultaneously. We demonstrate this technique for the Sun, which is bright on disk and faint off disk. We emulated these conditions in the lab to validate the method. We built an instrument simulator to demonstrate the method for a realistic solar imager and input. We then calculated S/Ns, finding a value of 45 for a faint coronal mass ejection and 200 for a bright one, both at 3.5



⊙

N

—meeting or far exceeding the international standard for digital photography that defines an S/N of 10 as acceptable and 40 as excellent. Future missions should consider this type of hardware and technique in their trade studies for instrument design.
Spatially Resolved Stellar Spectroscopy of the Ultra-diffuse Galaxy Dragonfly 44. III. Evidence for an Unexpected Star Formation History under Conventional Galaxy Evolution Processes
Authors: Villaume Alexa , Romanowsky Aaron J. , Brodie Jean , van Dokkum Pieter , Conroy Charlie , Forbes Duncan A. , Danieli Shany , Martin Christopher , Matuszewski Matt
Published: January 2022

We use the Keck Cosmic Web Imager integral field unit spectrograph to (1) measure the global stellar population parameters for the ultra-diffuse galaxy (UDG) Dragonfly 44 (DF44) to much higher precision than previously possible for any UDG and (2) for the first time measure spatially resolved stellar population parameters of a UDG. We find that DF44 falls below the mass–metallicity relation established by canonical dwarf galaxies both in and beyond the Local Group. We measure a flat radial age gradient (

m

logage

=
+

0.01

−
0.08

+
0.08

log Gyr kpc−1) and a flat to positive metallicity gradient (

m

[
Fe

/

H
]

=
+

0.09

−
0.12

+
0.11

dex kpc−1), which are inconsistent with the gradients measured in similarly pressure-supported dwarf galaxies. We also measure a negative [Mg/Fe] gradient (

m

[
Mg

/

Fe
]

=
−

0.20

−
0.18

+
0.18

) dex kpc−1 such that the central 1.5 kpc of DF44 has stellar population parameters comparable to metal-poor globular clusters. Overall, DF44 does not have internal properties similar to other dwarf galaxies and is inconsistent with it having been puffed up through a prolonged, bursty star formation history, as suggested by some simulations. Rather, the evidence indicates that DF44 experienced an intense epoch of “inside-out” star formation and then quenched early and catastrophically, such that star formation was cut off more quickly than in canonical dwarf galaxies.
Tracing Birth Properties of Stars with Abundance Clustering
Authors: Ratcliffe Bridget L. , Ness Melissa K. , Buck Tobias , Johnston Kathryn V. , Sen Bodhisattva , Beraldo e Silva Leandro , Debattista Victor P.
Published: January 2022

To understand the formation and evolution of the Milky Way disk, we must connect its current properties to its past. We explore hydrodynamical cosmological simulations to investigate how the chemical abundances of stars might be linked to their origins. Using hierarchical clustering of abundance measurements in two Milky Way–like simulations with distributed and steady star formation histories, we find that groups of chemically similar stars comprise different groups in birth place (R
birth) and time (age). Simulating observational abundance errors (0.05 dex), we find that to trace distinct groups of (R
birth, age) requires a large vector of abundances. Using 15 element abundances (Fe, O, Mg, S, Si, C, P, Mn, Ne, Al, N, V, Ba, Cr, Co), up to ≈10 groups can be defined with ≈25% overlap in (R
birth, age). We build a simple model to show that in the context of these simulations, it is possible to infer a star’s age and R
birth from abundances with precisions of ±0.06 Gyr and ±1.17 kpc, respectively. We find that abundance clustering is ineffective for a third simulation, where low-α stars form distributed in the disk and early high-α stars form more rapidly in clumps that sink toward the Galactic center as their constituent stars evolve to enrich the interstellar medium. However, this formation path leads to large age dispersions across the [α/Fe]–[Fe/H] plane, which is inconsistent with the Milky Way’s observed properties. We conclude that abundance clustering is a promising approach toward charting the history of our Galaxy.
Spectral Analysis of Solar Radio Type III Bursts from 20 kHz to 410 MHz
Authors: Sasikumar Raja K. , Maksimovic Milan , Kontar Eduard P. , Bonnin Xavier , Zarka Philippe , Lamy Laurent , Reid Hamish , Vilmer Nicole , Lecacheux Alain , Krupar Vratislav , Cecconi Baptiste , Nora Lahmiti , Denis Laurent
Published: January 2022

We present the statistical analysis of the spectral response of solar radio type III bursts over the wide frequency range between 20 kHz and 410 MHz. For this purpose, we have used observations that were carried out using both spaced-based (Wind/Waves) and ground-based (Nançay Decameter Array and Nançay Radioheliograph) facilities. In order to compare the flux densities observed by the different instruments, we have carefully calibrated the data and displayed them in solar flux units. The main result of our study is that type III bursts, in the metric to hectometric wavelength range, statistically exhibit a clear maximum of their median radio flux density around 2 MHz. Although this result was already reported by inspecting the spectral profiles of type III bursts in the frequency range 20 kHz–20 MHz, our study extends such analysis for the first time to metric radio frequencies (i.e., from 20 kHz to 410 MHz) and confirms the maximum spectral response around 2 MHz. In addition, using a simple empirical model we show that the median radio flux S of the studied data set obeys the polynomial form Y = 0.04X
3 − 1.63X
2 + 16.30X − 41.24, with

X
=
ln
(

F

MHz

)

and with

Y
=
ln
(

S

SFU

)

. Using the Sittler and Guhathakurtha model for coronal streamers, we have found that the maximum of radio power therefore falls in the range 4 to 10 R
⊙, depending on whether the type III emissions are assumed to be at the fundamental or the harmonic.
Impact of Hypernova νp-process Nucleosynthesis on the Galactic Chemical Evolution of Mo and Ru
Authors: Sasaki Hirokazu , Yamazaki Yuta , Kajino Toshitaka , Kusakabe Motohiko , Hayakawa Takehito , Cheoun Myung-Ki , Ko Heamin , Mathews Grant J.
Published: January 2022

We calculate the Galactic Chemical Evolution of Mo and Ru by taking into account the contribution from ν
p-process nucleosynthesis. We estimate yields of p-nuclei such as 92,94Mo and 96,98Ru through the ν
p-process in various supernova progenitors based upon recent models. In particular, the ν
p-process in energetic hypernovae produces a large amount of p-nuclei compared to the yield in ordinary core-collapse SNe. Because of this, the abundances of 92,94Mo and 96,98Ru in the Galaxy are significantly enhanced at [Fe/H] = 0 by the ν
p-process. We find that the ν
p-process in hypernovae is the main contributor to the elemental abundance of 92Mo at low metallicity [Fe/H] < −2. Our theoretical prediction of the elemental abundances in metal-poor stars becomes more consistent with observational data when the ν
p-process in hypernovae is taken into account.
Arecibo-Green Bank-LOFAR Carbon Radio Recombination Line Observations toward Cold H i Clouds
Authors: Roshi D. Anish , Peters W. M. , Emig K. L. , Salas P. , Oonk J. B. R. , Lebrón M. E. , Dickey J. M.
Published: January 2022

We present results from a search for radio recombination lines in three H i self-absorbing (HISA) clouds at 750 MHz and 321 MHz with the Robert C. Byrd Green Bank Telescope, and in three Galactic plane positions at 327 MHz with the Arecibo Telescope. We detect carbon recombination lines (CRRLs) in the direction of DR4 and DR21, as well as in the Galactic plane position G34.94 + 0.0. We additionally detect hydrogen recombination lines in emission in five of the six sightlines, and a Helium line at 750 MHz toward DR21. Combining our new data with 150 MHz Low Frequency Array detections of CRRL absorption toward DR4 and DR21, we estimate the electron densities of the line-forming regions by modeling the line width as a function of frequency. The estimated densities are in the range 1.4 → 6.5 cm−3 toward DR4, for electron temperatures 200 → 20 K. A dual line-forming region with densities between 3.5 → 24 cm−3 and 0.008 → 0.3 cm−3 could plausibly explain the observed line width as a function of frequency on the DR21 sight line. The central velocities of the CRRLs compare well with CO emission and HISA lines in these directions. The cloud densities estimated from the CO lines are smaller (at least a factor of five) than those of the CRRL-forming regions. It is likely that the CRRL-forming and HISA gas is located in a denser, shocked region either at the boundary of or within the CO emitting cloud.
Metallicity Distribution Function of the Eridanus II Ultra-faint Dwarf Galaxy from Hubble Space Telescope Narrowband Imaging
Authors: Fu Sal Wanying , Weisz Daniel R. , Starkenburg Else , Martin Nicolas , Ji Alexander P. , Patel Ekta , Boylan-Kolchin Michael , Côté Patrick , Dolphin Andrew E. , Longeard Nicolas , Mateo Mario L. , Sandford Nathan R.
Published: January 2022

We use deep narrowband CaHK (F395N) imaging taken with the Hubble Space Telescope (HST) to construct the metallicity distribution function (MDF) of Local Group ultra-faint dwarf galaxy Eridanus II (Eri II). When combined with archival F475W and F814W data, we measure metallicities for 60 resolved red giant branch stars as faint as m
F475W ∼ 24 mag, a factor of ∼4× more stars than current spectroscopic MDF determinations. We find that Eri II has a mean metallicity of [Fe/H] = −2.50

−
0.07

+
0.07

and a dispersion of

σ

[
Fe

/

H
]

=

0.42

−
0.06

+
0.06

, which are consistent with spectroscopic MDFs, though more precisely constrained owing to a larger sample. We identify a handful of extremely metal-poor star candidates (EMP; [Fe/H] < −3) that are marginally bright enough for spectroscopic follow-up. The MDF of Eri II appears well described by a leaky box chemical evolution model. We also compute an updated orbital history for Eri II using Gaia eDR3 proper motions, and find that it is likely on first infall into the Milky Way. Our findings suggest that Eri II underwent an evolutionary history similar to that of an isolated galaxy. Compared to MDFs for select cosmological simulations of similar mass galaxies, we find that Eri II has a lower fraction of stars with [Fe/H] < −3, though such comparisons should currently be treated with caution due to a paucity of simulations, selection effects, and known limitations of CaHK for EMPs. This study demonstrates the power of deep HST CaHK imaging for measuring the MDFs of UFDs.
Observationally Constraining the Starspot Properties of Magnetically Active M67 Sub-subgiant S1063
Authors: Gosnell Natalie M. , Gully-Santiago Michael A. , Leiner Emily M. , Tofflemire Benjamin M.
Published: January 2022

Our understanding of the impact of magnetic activity on stellar evolution continues to unfold. This impact is seen in sub-subgiant stars, defined to be stars that sit below the subgiant branch and red of the main sequence in a cluster color–magnitude diagram. Here we focus on S1063, a prototypical sub-subgiant in open cluster M67. We use a novel technique combining a two-temperature spectral decomposition and light-curve analysis to constrain starspot properties over a multiyear time frame. Using a high-resolution near-infrared IGRINS spectrum and photometric data from K2 and ASAS-SN, we find a projected spot filling factor of 32% ± 7% with a spot temperature of 4000 ± 200 K. This value anchors the variability seen in the light curve, indicating the spot filling factor of S1063 ranged from 20% to 45% over a four-year time period with an average spot filling factor of 30%. These values are generally lower than those determined from photometric model comparisons but still indicate that S1063, and likely other sub-subgiants, are magnetically active spotted stars. We find observational and theoretical comparisons of spotted stars are nuanced due to the projected spot coverage impacting estimates of the surface-averaged effective temperature. The starspot properties found here are similar to those found in RS CVn systems, supporting classifying sub-subgiants as another type of active giant star binary system. This technique opens the possibility of characterizing the surface conditions of many more spotted stars than previous methods, allowing for larger future studies to test theoretical models of magnetically active stars.
Radiation and Polarization Signatures from Magnetic Reconnection in Relativistic Jets. II. Connection with γ-Rays
Authors: Zhang Haocheng , Li Xiaocan , Giannios Dimitrios , Guo Fan , Thiersen Hannes , Böttcher Markus , Lewis Tiffany , Venters Tonia
Published: January 2022

It is commonly believed that blazar jets are relativistic magnetized plasma outflows from supermassive black holes. One key question is how the jets dissipate magnetic energy to accelerate particles and drive powerful multiwavelength flares. Relativistic magnetic reconnection has been proposed as the primary plasma physical process in the blazar emission region. Recent numerical simulations have shown strong acceleration of nonthermal particles that may lead to multiwavelength flares. Nevertheless, previous works have not directly evaluated γ-ray signatures from first-principles simulations. In this paper, we employ combined particle-in-cell and polarized radiation transfer simulations to study multiwavelength radiation and optical polarization signatures under the leptonic scenario from relativistic magnetic reconnection. We find harder-when-brighter trends in optical and Fermi-LAT γ-ray bands as well as closely correlated optical and γ-ray flares. The swings in optical polarization angle are also accompanied by γ-ray flares with trivial time delays. Intriguingly, we find highly variable synchrotron self-Compton signatures due to inhomogeneous particle distributions during plasmoid mergers. This feature may result in fast γ-ray flares or orphan γ-ray flares under the leptonic scenario, complementary to the frequently considered minijet scenario. It may also imply neutrino emission with low secondary synchrotron flux under the hadronic scenario, if plasmoid mergers can accelerate protons to very high energy.
Observing Ram Pressure at Work in Intermediate Redshift Clusters with MUSE: The Case of Abell 2744 and Abell 370
Authors: Moretti Alessia , Radovich Mario , Poggianti Bianca M. , Vulcani Benedetta , Gullieuszik Marco , Werle Ariel , Bellhouse Callum , Bacchini Cecilia , Fritz Jacopo , Soucail Genevieve , Richard Johan , Franchetto Andrea , Tomičić Neven , Omizzolo Alessandro
Published: January 2022

Ram pressure stripping has been proven to be effective in shaping galaxy properties in dense environments at low redshift. The availability of Multi Unit Spectroscopic Explorer (MUSE) observations of a sample of distant (z ∼ 0.3–0.5) clusters has allowed one to search for galaxies subject to this phenomenon at significant lookback times. In this paper we describe how we discovered and characterized 13 ram-pressure-stripped galaxies in the central regions of two intermediate redshift (z ∼ 0.3–0.4) clusters, A2744 and A370, using the MUSE spectrograph. Emission-line properties as well as stellar features have been analyzed to infer the presence of this gas-only stripping mechanism, that produces spectacular ionized gas tails (Hα and even more astonishing [O ii](3727, 3729)) departing from the main galaxy body. The inner regions of these two clusters reveal the predominance of such galaxies among blue star-forming cluster members, suggesting that ram pressure stripping was even more effective at intermediate redshift than in today’s universe. Interestingly, the resolved [O ii]/Hα line ratio in the stripped tails is exceptionally high compared to that in the disks of these galaxies, (which is comparable to that in normal low-z galaxies), suggesting lower gas densities and/or an interaction with the hot surrounding intracluster medium.
Direct Observation of the Radial Magnetic Field Gradient in HD 58260 from Spectropolarimetry of NLTE Lines in Emission
Authors: Giarrusso Marina
Published: January 2022

Because of the unquestionable presence of magnetic fields in stars, their role in the structure of stellar atmospheres has for a long time been a subject of speculation. In our contribution to this discussion we present spectropolarimetric evidence of the decrease of the radial component of the magnetic field with altitude in the atmosphere of HD 58260, a B-type magnetic star on the main sequence. We show that the Stokes V profiles of metal lines in emission of the outer atmosphere are evidence for a field three times weaker than absorption lines from inner layers. The extra flow of energetic particles due to the magnetic-gradient pumping mechanism could be at the origin of the magnetospheres surrounding this class of stars and at the basis of the high-energy phenomena observed. We also list a series of spectral lines useful for measuring the surface field of early-type stars.
Stochastic Electron Acceleration by Temperature Anisotropy Instabilities under Solar Flare Plasma Conditions
Authors: Riquelme Mario , Osorio Alvaro , Verscharen Daniel , Sironi Lorenzo
Published: January 2022

Using 2D particle-in-cell plasma simulations, we study electron acceleration by temperature anisotropy instabilities, assuming conditions typical of above-the-loop-top sources in solar flares. We focus on the long-term effect of T

e,⊥ > T

e,∥ instabilities by driving the anisotropy growth during the entire simulation time through imposing a shearing or a compressing plasma velocity (T

e,⊥ and T

e,∥ are the temperatures perpendicular and parallel to the magnetic field). This magnetic growth makes T

e,⊥/T

e,∥ grow due to electron magnetic moment conservation, and amplifies the ratio ω
ce/ω
pe from ∼0.53 to ∼2 (ω
ce and ω
pe are the electron cyclotron and plasma frequencies, respectively). In the regime ω
ce/ω
pe ≲ 1.2–1.7, the instability is dominated by oblique, quasi-electrostatic modes, and the acceleration is inefficient. When ω
ce/ω
pe has grown to ω
ce/ω
pe ≳ 1.2–1.7, electrons are efficiently accelerated by the inelastic scattering provided by unstable parallel, electromagnetic z modes. After ω
ce/ω
pe reaches ∼2, the electron energy spectra show nonthermal tails that differ between the shearing and compressing cases. In the shearing case, the tail resembles a power law of index α

s
∼ 2.9 plus a high-energy bump reaching ∼300 keV. In the compressing runs, α

s
∼ 3.7 with a spectral break above ∼500 keV. This difference can be explained by the different temperature evolutions in these two types of simulations, suggesting that a critical role is played by the type of anisotropy driving, ω
ce/ω
pe, and the electron temperature in the efficiency of the acceleration.
Let the Great World Spin: Revealing the Stormy, Turbulent Nature of Young Giant Exoplanet Analogs with the Spitzer Space Telescope
Authors: Vos Johanna M. , Faherty Jacqueline K. , Gagné Jonathan , Marley Mark , Metchev Stanimir , Gizis John , Rice Emily L. , Cruz Kelle
Published: January 2022

We present a survey for photometric variability in young, low-mass brown dwarfs with the Spitzer Space Telescope. The 23 objects in our sample show robust signatures of youth and share properties with directly imaged exoplanets. We present three new young objects: 2MASS J03492367+0635078, 2MASS J09512690−8023553, and 2MASS J07180871−6415310. We detect variability in 13 young objects, and find that young brown dwarfs are highly likely to display variability across the L2–T4 spectral type range. In contrast, the field dwarf variability occurrence rate drops for spectral types >L9. We examine the variability amplitudes of young objects and find an enhancement in maximum amplitudes compared to field dwarfs. We speculate that the observed range of amplitudes within a spectral type may be influenced by secondary effects such as viewing inclination and/or rotation period. We combine our new rotation periods with the literature to investigate the effects of mass on angular momentum evolution. While high-mass brown dwarfs (>30M
Jup) spin up over time, the same trend is not apparent for lower-mass objects (<30M
Jup), likely due to the small number of measured periods for old, low-mass objects. The rotation periods of companion brown dwarfs and planetary-mass objects are consistent with those of isolated objects with similar ages and masses, suggesting similar angular momentum histories. Within the AB Doradus group, we find a high-variability occurrence rate and evidence for common angular momentum evolution. The results are encouraging for future variability searches in directly imaged exoplanets with facilities such as the James Webb Space Telescope and 30 m telescopes.
The Milky Way Revealed by Variable Stars. I. Sample Selection of RR Lyrae Stars and Evidence for Merger History
Authors: Ablimit Iminhaji , Zhao Gang , Teklimakan Uy. , Shi Jian-Rong , Abdusalam Kunduz
Published: January 2022

In order to study the Milky Way, RR Lyrae (RRL) variable stars identified by Gaia, ASAS-SN, and ZTF sky survey projects have been analyzed as tracers in this work. Photometric and spectroscopic information of 3417 RRLs including proper motions, radial velocity, and metallcity are obtained from observational data of Gaia, LAMOST, GALAH, APOGEE, and RAVE. Precise distances of RRLs with typical uncertainties less than 3% are derived by using a recent comprehensive period–luminosity–metallicity relation. Our results from kinematical and chemical analysis provide important clues for the assembly history of the Milky Way, especially for the Gaia–Sausage ancient merger. The kinematical and chemical trends found in this work are consistent with those of recent simulations that indicated that the Gaia–Sausage merger had a dual origin in the Galactic thick disk and halo. As recent similar works have found, the halo RRL sample in this work contains a subset of radially biased orbits besides a more isotropic component. This higher orbital anisotropy component amounts to β ≃ 0.8, and it contributes between 42% and 83% of the halo RRLs at 4 < R( kpc) < 20.
A Cross-laboratory Comparison Study of Titan Haze Analogs: Surface Energy
Authors: Li 李 Jialin 嘉霖 , Yu 余 Xinting 馨婷 , Sciamma-O’Brien Ella , He Chao , Sebree Joshua A. , Salama Farid , Hörst Sarah M. , Zhang Xi
Published: January 2022

In Titan’s nitrogen-methane atmosphere, photochemistry leads to the production of complex organic particles, forming Titan’s thick haze layers. Laboratory-produced aerosol analogs, or “tholins,” are produced in a number of laboratories; however, most previous studies have investigated analogs produced by only one laboratory rather than a systematic, comparative analysis. In this study, we performed a comparative study of an important material property, the surface energy, of seven tholin samples produced in three independent laboratories under a broad range of experimental conditions, and we explored their commonalities and differences. All seven tholin samples are found to have high surface energies and are therefore highly cohesive. Thus, if the surface sediments on Titan are similar to tholins, future missions such as Dragonfly will likely encounter sticky sediments. We also identified a commonality between all the tholin samples: a high dispersive (nonpolar) surface energy component of at least 30 mJ m−2. This common property could be shared by the actual haze particles on Titan as well. Given that the most abundant species interacting with the haze on Titan (methane, ethane, and nitrogen) are nonpolar in nature, the dispersive surface energy component of the haze particles could be a determinant factor in condensate−haze and haze−lake liquid interactions on Titan. With this common trait of tholin samples, we confirmed the findings of a previous study by Yu et al. that haze particles are likely good cloud condensation nuclei for methane and ethane clouds and would likely be completely wetted by the hydrocarbon lakes on Titan.
General Public Awareness about the Indications and Complications of Sleeve Gastrectomy in Qassim Region, Saudi Arabia
Authors: Alolayan Hayfa , Aldubayyan Anwar , Aldhohayan Asma , AlBassam Rawaf , Almarzuqi Shoug , Almoqaiteb Taif , Almutlaq Ghadah , Alquwayfili Lubna
Published: January 2022

BACKGROUND: Sleeve gastrectomy has become prevalent worldwide regardless of the patient’s awareness about the indications and complications. That would affect their judgment and decision.
AIM: This study aimed to assess the level of awareness about indications and complications of sleeve gastrectomy in the general public at Al-Qassim, Saudi Arabia in 2021.
MATERIALS AND METHODS: This is a quantitative cross-sectional study conducted among the general public living in the Qassim region, Saudi Arabia. Using a convenience sampling technique to select the participants as a representative sample for the general population. The target population will include all Saudis, who live in Al-Qassim and aged above 18 years, and will exclude who does not live in al-Qassim, age under 18 years, non-Saudi, who does not complete the questionnaire and who refuse to participate. The data were collected using a validated self-administered questionnaire. Questionnaires include; demographic characteristics, general awareness about sleeve gastrectomy, and awareness toward the indication and complication of sleeve gastrectomy. All statistical analyses were performed using Statistical Packages for Software Sciences version 26.
RESULTS: A total of 1091 respondents took part. The mean age of the respondents was 37.5 (SD 12.9) years old with females dominating the males (87.8% vs. 12.2%). Awareness about the indications and complications of sleeve gastrectomy constitutes 49% and 82.4%, respectively. In univariate analyses, those who have heard about body mass index (BMI) had greater knowledge of the indications and complications of sleeve gastrectomy. In a multivariate regression model, gender female was the independent significant predictor of sleeve gastrectomy complications whereas those who heard of BMI was the independent significant predictor of the knowledge toward the indications and complications of sleeve gastrectomy.
CONCLUSION: The general public demonstrated a lack of knowledge regarding the indications of sleeve gastrectomy but their knowledge about complications was better. Better knowledge about BMI comes with a better awareness of the indications and complications of sleeve gastrectomy.
A new genus and species of leptonetid spiders (Araneae, Leptonetidae) from Guangdong Province, China
Authors: Yang Kuiwen , Li Hanchao , Tong Yanfeng , Bian Dongju
Published: January 2022

The spider family Leptonetidae Simon, 1890 includes 20 genera and 366 species from North America, the Mediterranean Region and Asia. Currently, 132 species belonging to six genera have been recorded in China.

A new genus and species of leptonetid spiders,Yueleptoneta dongxinggen. et sp. n., is described from Guangdong Province, China.Yueleptonetagen. n. is distinct from the other genera in the chelicerae having the stridulatory file on the lateral margin and the male palp having a tarsal spur, lacking strong spines or apophyses on the femur and tibia.
The genus Cacodaemon (Coleoptera, Endomychidae) of Vietnam
Authors: Yoshitomi Hiroyuki , Pham Thai Hong
Published: January 2022

The species of the genus Cacodaemon of Vietnam are revised. A new species, Cacodaemon vietnamensissp. nov., is described and C. laotinus laotinus (Arrow, 1920) is newly recorded from Vietnam. A previously known species, C. proavus Strohecker, 1964 is redescribed based on an additional female specimen and a key to species of the genus Cacodaemon in Vietnam is provided.
Note de lecture
Authors: Jounin Nicolas
Published: January 2022

Le geste taylorien consiste en une revendication du monopole de la représentation rationnelle de l’activité de travail. Dans les textes de l’ingénieur qui a donné son nom au taylorisme, le scientific management apparaît comme un système statique (une fois qu’il est pleinement déployé), autonome (n’articulant d’autre logique que la sienne, excluant apparemment toute considération sur les propriétés sociales des acteurs), qui met en rapport des figures abstraites (employeur et salariés) enfin réconciliées par un juge de paix (la science des temps et mouvements). Taylor ne donne aucune place analytique à l’articulation entre travail et hors-travail, ou encore aux propriétés sociales des acteurs de son système, en particulier des dispositions constituées en dehors de l’usine. Pourtant, à la faveur d’anecdotes, dont il est friand, mais aussi de réponses à ses détracteurs, Taylor dessine par petites touches un arrière-plan implicite de positions et de dispositions qui dépassent la seule sphère de l’atelier et forment les conditions de possibilité du grand récit qu’il soumet à ses lecteurs. Contrariant la belle image de la transcendance d’un dispositif supposé réconcilier les classes, Taylor mobilise en plusieurs endroits les propriétés sociales des protagonistes de son système (à commencer par lui-même), leur donnant une épaisseur historique dont ils semblaient dépourvus, rappelant des contingences d’ordinaire sous-entendues, et pourtant décisives.