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14811. Stellar rotation periods for KOIs
ID:
ivo://CDS.VizieR/J/ApJ/775/L11
Title:
Stellar rotation periods for KOIs
Short Name:
J/ApJ/775/L11
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a large sample of stellar rotation periods for Kepler Objects of Interest, based on three years of public Kepler data. These were measured by detecting periodic photometric modulation caused by star spots, using an algorithm based on the autocorrelation function of the light curve, developed recently by McQuillan, Aigrain & Mazeh (2013). Of the 1919 main-sequence exoplanet hosts analyzed, robust rotation periods were detected for 737. Comparing the detected stellar periods to the orbital periods of the innermost planet in each system reveals a notable lack of close-in planets around rapid rotators. It appears that only slowly spinning stars with rotation periods longer than 5-10 days host planets on orbits shorter than 2 or 3 days, although the mechanism(s) that lead(s) to this is not clear.
14812. Stellar rotation periods from K2 Campaigns 0-18
ID:
ivo://CDS.VizieR/J/A+A/635/A43
Title:
Stellar rotation periods from K2 Campaigns 0-18
Short Name:
J/A+A/635/A43
Date:
21 Oct 2021
Publisher:
CDS
Description:
Rotation period measurements of stars observed with the Kepler mission have revealed a lack of stars at intermediate rotation periods, accompanied by a decrease of photometric variability. Whether this so-called dearth region is a peculiarity of stars in the Kepler field, or reflects a general manifestation of stellar magnetic activity, is still under debate. The K2 mission has the potential to unravel this mystery by measuring stellar rotation and photometric variability along different fields in the sky. Our goal is to measure stellar rotation periods and photometric variabilities for tens of thousands of K2 stars, located in different fields along the ecliptic plane, to shed light on the relation between stellar rotation and photometric variability. We use Lomb-Scargle periodograms, auto-correlation and wavelet functions to determine consistent rotation periods. Stellar brightness variability is assessed by computing the variability range, R_var_, from the light curve. We further apply Gaussian mixture models to search for bimodality in the rotation period distribution. Combining measurements from all K2 campaigns, we detect rotation periods in 29860 stars. The reliability of these periods was estimated from stars observed more than once. We find that 75-90% of the stars show period deviation smaller than 20% between different campaigns, depending on the peak height threshold in the periodograms. For effective temperatures below 6000K, the variability range shows a local minimum at different periods, consistent with an isochrone age of ~750Myr. Additionally, the rotation period distribution shows evidence for bimodality, although the dearth region in the K2 data is less pronounced compared to the Kepler field. The period at the dip of the bimodal distribution shows good agreement with the period at the local variability minimum. We conclude that the rotation period bimodality is present in different fields of the sky, and is hence a general manifestation of stellar magnetic activity. The reduced variability in the dearth region is interpreted as a cancelation between dark spots and bright faculae. Our results strongly advocate that the role of faculae has been underestimated so far, suggesting a more complex dependence of the brightness variability on the rotation period.
14813. Stellar specific angular momentum & mass relation
ID:
ivo://CDS.VizieR/J/ApJ/860/37
Title:
Stellar specific angular momentum & mass relation
Short Name:
J/ApJ/860/37
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the relation between stellar specific angular momentum j*, stellar mass M*, and bulge-to-total light ratio {beta} for The HI Nearby Galaxy Survey, the Calar Alto Legacy Integral Field Area Survey, and Romanowsky & Fall (2012ApJS..203...17R) data sets, exploring the existence of a fundamental plane between these parameters, as first suggested by Obreschkow & Glazebrook (2014ApJ...784...26O). Our best-fit M*-j* relation yields a slope of {alpha}=1.03+/-0.11 with a trivariate fit including {beta}. When ignoring the effect of {beta}, the exponent {alpha}=0.56+/-0.06 is consistent with {alpha}=2/3 that is predicted for dark matter halos. There is a linear {beta}-j*/M* relation for {beta}<~0.4, exhibiting a general trend of increasing {beta} with decreasing j*/M*. Galaxies with {beta}>~0.4 have higher j* than predicted by the relation. Pseudobulge galaxies have preferentially lower {beta} for a given j*/M* than galaxies that contain classical bulges. Pseudobulge galaxies follow a well- defined track in {beta}-j*/M* space, consistent with Obreschkow & Glazebrook, while galaxies with classical bulges do not. These results are consistent with the hypothesis that while growth in either bulge type is linked to a decrease in j*/M*, the mechanisms that build pseudobulges seem to be less efficient at increasing bulge mass per decrease in specific angular momentum than those that build classical bulges.
14814. Stellar Spectra Classified in Morgan-Keenan System
ID:
ivo://CDS.VizieR/III/18B
Title:
Stellar Spectra Classified in Morgan-Keenan System
Short Name:
III/18B
Date:
21 Oct 2021
Publisher:
CDS
Description:
The purpose of this catalog is to provide bibliographic references to spectral classifications of stars in the Morgan-Keenan system published in the literature prior to January 1963. The catalog includes, with few exceptions, only objects contained in the Durchmusterungen: BD, SD, CD, and CPD. Objects belonging to stellar clusters and extragalactic nebulae were excluded from the catalog if they are not listed in the Durchmusterungen. The catalog includes sequential numbers, HD and DM numbers, right ascension and declination (B1900.0), magnitudes, spectral classifications, and bibliographic references. This machine-readable version was modified and corrected with errata at the Astronomical Data Center/Goddard Space Flight Center, NASA/Goddard Space Flight Center.
14815. Stellar Spectrophotometric Atlas
ID:
ivo://CDS.VizieR/III/88
Title:
Stellar Spectrophotometric Atlas
Short Name:
III/88
Date:
21 Oct 2021
Publisher:
CDS
Description:
The data were obtained with the Oke multichannel scanner on the 5-meter Hale reflector for purposes of synthetizing galaxy spectra, and the digitized atlas contains normalized spectral energy distributions, computed colors, scan line and continuum indices for 175 selected stars covering the complete ranges of spectral type and luminosity class.
14816. Stellar Spectrophotometry
ID:
ivo://CDS.VizieR/III/89
Title:
Stellar Spectrophotometry
Short Name:
III/89
Date:
21 Oct 2021
Publisher:
CDS
Description:
The catalog is a collection of spectrophotometric measurements obtained with rotating grating scanners attached to various telescopes at the Kitt Peak National, Mount Wilson, and Palomar Observatories. The observations were made during the 1970s and early 1980s, both individually and jointly, by S.J. Adelman, D.M. Pyper, S.N. Shore, and R.E. White. All measurements were calibrated with the fluxes of Alpha Lyrae (Vega) as presented by Hayes and Latham (1975ApJ...197..593H). There are 1134 observations concerning 207 individual stars.
14817. Stellar stream in Gaia DR2 discovery
ID:
ivo://CDS.VizieR/J/A+A/622/L13
Title:
Stellar stream in Gaia DR2 discovery
Short Name:
J/A+A/622/L13
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery of a large, dynamically cold, coeval stellar stream that is currently traversing the immediate solar neighborhood at a distance of only 100pc. The structure was identified in a wavelet decomposition of the 3D velocity space of all stars within 300pc of the Sun. Its members form a highly elongated structure with a length of at least 400pc, while its vertical extent measures only about 50pc. Stars in the stream are not isotropically distributed but instead form two parallel lanes with individual local overdensities, that may correspond to a remnant core of a tidally disrupted cluster or OB association. Its members follow a very well-defined main sequence in the observational Hertzsprung-Russel diagram and also show a remarkably low 3D velocity dispersion of only 1.3km/s. These findings strongly suggest a common origin as a single coeval stellar population. An extrapolation of the present-day mass function indicates a total mass of at least 2000M_{sun}_, making it larger than most currently known clusters or associations in the solar neighborhood. We estimated the age of the stream to be around 1 Gyr based on a comparison with a set of isochrones and giant stars in our member selection and find a mean metallicity of [Fe/H]=-0.04. This structure may very well represent the Galactic disk counterpart to the prominent stellar streams observed in the Milky Way halo. As such, it constitutes a new valuable probe to constrain the Galaxy's mass distribution.
14818. Stellar streams in Andromeda (M31)
ID:
ivo://CDS.VizieR/J/MNRAS/390/1437
Title:
Stellar streams in Andromeda (M31)
Short Name:
J/MNRAS/390/1437
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a spectroscopic analysis of five stellar streams ("A", "B", "Cr", "Cp" and "D") as well as the extended star cluster, EC4, which lies within Stream "C", all discovered in the halo of M31 from our Canada-France-Hawaii Telescope/MegaCam survey. These spectroscopic results were initially serendipitous, making use of our existing observations from the DEep Imaging Multi-Object Spectrograph mounted on the Keck II telescope, and thereby emphasizing the ubiquity of tidal streams that account for ~70 per cent of the M31 halo stars in the targeted fields. Subsequent spectroscopy was then procured in Stream "C" and Stream "D" to trace the velocity gradient along the streams. Nine metal-rich ([Fe/H]~-0.7) stars at v_hel_=-349.5km/s, {sigma}_v,corr_~5.1+/-2.5km/s are proposed as a serendipitous detection of Stream "Cr", with follow-up kinematic identification at a further point along the stream. Seven metal-poor ([Fe/H]~-1.3) stars confined to a narrow, 15km/s velocity bin centred at v_hel_=-285.6, {sigma}_v,corr_=4.3^+1.7^_-1.4_km/s represent a kinematic detection of Stream "Cp", again with follow-up kinematic identification further along the stream. For the cluster EC4, candidate member stars with average [Fe/H]~-1.4, are found at v_hel_=-282 suggesting it could be related to Stream "Cp". No similarly obvious cold kinematic candidate is found for Stream "D", although candidates are proposed in both of two spectroscopic pointings along the stream (both at ~-400km/s). Spectroscopy near the edge of Stream "B" suggests a likely kinematic detection at v_hel_~-330, {sigma}_v,corr_~6.9km/s, while a candidate kinematic detection of Stream "A" is found (plausibly associated to M33 rather than M31) with v_hel_~-170, {sigma}_v,corr_=12.5km/s. The low dispersion of the streams in kinematics, physical thickness and metallicity makes it hard to reconcile with a scenario whereby these stream structures as an ensemble are related to the giant southern stream. We conclude that the M31 stellar halo is largely made up of multiple kinematically cold streams.
14819. Stellar structure models of edge-on galaxies
ID:
ivo://CDS.VizieR/J/A+A/610/A5
Title:
Stellar structure models of edge-on galaxies
Short Name:
J/A+A/610/A5
Date:
21 Oct 2021
Publisher:
CDS
Description:
Recent studies have made the community aware of the importance of accounting for scattered light when examining low-surface-brightness galaxy features such as thick discs. In our past studies of the thick discs of edge-on galaxies in the Spitzer Survey of Stellar Structure in Galaxies - the S4G - we modelled the point spread function as a Gaussian. In this paper we re- examine our results using a revised point spread function model that accounts for extended wings out to more than 2.5arcmin. We study the 3.6micron images of 141 edge-on galaxies from the S4G and its early-type galaxy extension. Thus, we more than double the samples examined in our past studies. We decompose the surface-brightness profiles of the galaxies perpendicular to their mid-planes assuming that discs are made of two stellar discs in hydrostatic equilibrium. We decompose the axial surface- brightness profiles of galaxies to model the central mass concentration - described by a Sersic function - and the disc - described by a broken exponential disc seen edge-on. Our improved treatment fully confirms the ubiquitous occurrence of thick discs. The main difference between our current fits and those presented in our previous papers is that now the scattered light from the thin disc dominates the surface brightness at levels below ~26mag/arcsec^2^. We stress that those extended thin disc tails are not physical, but pure scattered light. This change, however, does not drastically affect any of our previously presented results: 1) Thick discs are nearly ubiquitous. They are not an artefact caused by scattered light as has been suggested elsewhere. 2) Thick discs have masses comparable to those of thin discs in low-mass galaxies - with circular velocities vc<120km/s - whereas they are typically less massive than the thin discs in high-mass galaxies. 3) Thick discs and central mass concentrations seem to have formed at the same epoch from a common material reservoir. 4) Approximately 50% of the up-bending breaks in face-on galaxies are caused by the superposition of a thin and a thick disc where the scale-length of the latter is the largest.
14820. Stellar surface gravity measures of KIC stars
ID:
ivo://CDS.VizieR/J/ApJ/818/43
Title:
Stellar surface gravity measures of KIC stars
Short Name:
J/ApJ/818/43
Date:
21 Oct 2021
Publisher:
CDS
Description:
In our previous work we found that high-quality light curves, such as those obtained by Kepler, may be used to measure stellar surface gravity via granulation-driven light curve "flicker" (F_8_). Here, we update and extend the relation originally presented by Bastien et al. (2013Natur.500..427B) after calibrating F_8_ against a more robust set of asteroseismically derived surface gravities. We describe in detail how we extract the F_8_ signal from the light curves, including how we treat phenomena, such as exoplanet transits and shot noise, that adversely affect the measurement of F_8_. We examine the limitations of the technique, and, as a result, we now provide an updated treatment of the F_8_-based log g error. We briefly highlight further applications of the technique, such as astrodensity profiling or its use in other types of stars with convective outer layers. We discuss potential uses in current and upcoming space-based photometric missions. Finally, we supply F_8_-based log g values, and their uncertainties, for 27628 Kepler stars not identified as hosts of transiting planets, with 4500K<T_eff_<7150K, 2.5<logg<4.6, K_p_<=13.5, and overall photometric amplitudes <10 parts per thousand.

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