- ID:
- ivo://CDS.VizieR/J/A+AS/97/729
- Title:
- JHKL'M Observations of O-Rich late-type star
- Short Name:
- J/A+AS/97/729
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a photometric monitoring in the wavelength range 1-20um are presented for 37 oxygen-rich sources. The sample contains optically identified miras (13), M-type supergiants (3), type II OH/IR sources (20) and one unidentified object. Each source was observed on at least 13 occasions (up to 42) over a lapse of at least 1250 days (up to 2150) between 1984 and 1990 with the ESO 1-m telescope equipped with its standard infrared photometer.
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- ID:
- ivo://CDS.VizieR/J/A+A/458/533
- Title:
- JHKL' photometry of selected AGB stars
- Short Name:
- J/A+A/458/533
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a near-infrared monitoring programme of a selected sample of stars, initially suspected to be Mira variables and OH/IR stars, covering more than a decade of observations. The objects monitored cover the typical range of IRAS colours shown by O-rich stars on the asymptotic giant branch and show a surprisingly large diversity of variability properties. Sixteen objects are confirmed as large-amplitude variables.
- ID:
- ivo://CDS.VizieR/J/ApJ/353/494
- Title:
- JHKL photometry on Galactic bulge M Giants
- Short Name:
- J/ApJ/353/494
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- JHKL colors and CO and H2O indices are presented for an unbiased sample of about 250 M giants drawn from complete surveys for such stars along the minor axis of the Galaxy at latitudes between -3deg and -12deg. Magnitudes at 10 {mu}m and narrow-band near-infrared colors for some of these stars are also given. At constant J-K the mean CO index of the bulge M giants weakens monotonically with increasing latitude. From the relation between CO and [Fe/H] established for star clusters, this would correspond to a decrease of ~0.4 dex in the mean [Fe/H] between the -3deg and -12deg fields, from somewhat greater to somewhat less than solar. These values are consistent with abundances derived from optical color-magnitude diagrams. Despite these high [Fe/H] values, the ridgelines of the color-magnitude diagrams for all fields lie between those of 47 Tucanae and M3. There is a mild blueward shift with increasing latitude seen in the integrated mean J-K colors of the fields. A steady progression with latitude in the mean (J-H, H-K) relation for the bulge M giants is observed. For the -12deg field it is significantly displaced from the one for local field giants and overlaps that for globular cluster stars; for the -3deg field it is displaced by about the same amount, but on the opposite side of the field giant relation. Dispersions about this relation and the mean (CO, J-K) relation for the M giants in each field are comparable in size to the measuring uncertainties alone, but in a given field the displacements of individual stars from these two mean relations are statistically correlated. We attribute this correlation to a spread in metallicity within each field but note that this spread is smaller than the total metallicity range over all fields. In addition, metallicity-related effects result in J-H getting bluer with increasing metallicity in stars of similar temperature. The bolometric luminosity function of the nonvariable M giants is nearly independent of latitude. All show a sharp cutoff at Mbol<=-4.2; such a cutoff could be a good extragalactic distance indicator for bulgelike stellar populations. The reddest (J-K>=-1.35) and most luminous stars are found only in the low-latitude windows; all are M7-M9 giants, long-period variables (LPVs), or both. Except for these reddest stars, the ratio at a given color of M7-M9 giants to earlier type giants is independent of latitude. Only when stars of all colors in a spectral group are considered is the rapid falloff seen in the ratio of M7-M9 giants respect to earlier types. The bulge LPVs have <Mbol> = -4.2. Since this is nearly the same as for LPVs in globular clusters, it does not require an age for the bulge population significantly younger than that of globular clusters. Their spatial distribution is similar to that of the reddest late M giants. The LPVs with the reddest colors, attributed to the most extensive circumstellar dust shells, are found in the lowest latitude fields. Most of the bulge IRAS sources in the fields studied can be identified with these LPVs or with the brightest nonvariable M giants; many of the latter are probably foreground objects. The reddest IRAS sources are at the lowest latitudes and have the coolest [12-25]{mu}m colors. The bulge IRAS sources do not appear to represent a different or more luminous class of objects than the optically identified M giants. Five different estimators of the surface brightness and surface density between latitudes -3deg and -12deg have a power-law dependence on radius with exponent between -2.5 and -3.4. The value of the exponent depends on the metallicity of the estimator: the most metal-rich objects have the steepest falloff. However, even the smallest exponent, which characterizes the total light and mass distribution, places the bulge among the most spatially concentrated of those measured by Kent for a sample of 22 Sb-Sc galaxies. Thus the mass distribution within the inner 1.5 kpc of the Galaxy is quite sharply peaked.
- ID:
- ivo://CDS.VizieR/J/AJ/127/3553
- Title:
- JHK photometry and spectroscopy for L and T dwarfs
- Short Name:
- J/AJ/127/3553
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new JHK photometry on the MKO-NIR (Mauna Kea Observatories Near-Infrared) system and JHK spectroscopy for a large sample of L and T dwarfs. Photometry has been obtained for 71 dwarfs, and spectroscopy for 56. The sample comprises newly identified very red objects from the Sloan Digital Sky Survey (SDSS, http://www.sdss.org/) and known dwarfs from the SDSS and the Two Micron All Sky Survey (2MASS, Cat. <II/246>). Spectral classification has been carried out using four previously defined indices from Geballe et al. (2002ApJ...564..466G) that measure the strengths of the near infrared water and methane bands.
- ID:
- ivo://CDS.VizieR/J/A+A/375/989
- Title:
- JHK photometry of Praesepe low-mass stars
- Short Name:
- J/A+A/375/989
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- File table 1 contains the list of low-mass Praesepe stars observed with adaptive optics and which were not resolved as multiple systems.
- ID:
- ivo://CDS.VizieR/J/AJ/154/250
- Title:
- Kepler EB classifications and rotation periods
- Short Name:
- J/AJ/154/250
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Few observational constraints exist for the tidal synchronization rate of late-type stars, despite its fundamental role in binary evolution. We visually inspected the light curves of 2278 eclipsing binaries (EBs) from the Kepler Eclipsing Binary Catalog to identify those with starspot modulations, as well as other types of out-of-eclipse variability. We report rotation periods for 816 EBs with starspot modulations, and find that 79% of EBs with orbital periods of less than 10 days are synchronized. However, a population of short-period EBs exists, with rotation periods typically 13% slower than synchronous, which we attribute to the differential rotation of high-latitude starspots. At 10 days, there is a transition from predominantly circular, synchronized EBs to predominantly eccentric, pseudosynchronized EBs. This transition period is in good agreement with the predicted and observed circularization period for Milky Way field binaries. At orbital periods greater than about 30 days, the amount of tidal synchronization decreases. We also report 12 previously unidentified candidate {delta} Scuti and {gamma} Doradus pulsators, as well as a candidate RS CVn system with an evolved primary that exhibits starspot occultations. For short-period contact binaries, we observe a period-color relation and compare it to previous studies. As a whole, these results represent the largest homogeneous study of tidal synchronization of late-type stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/871/174
- Title:
- Kepler rapid rotators and Ks-band excesses
- Short Name:
- J/ApJ/871/174
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tens of thousands of rotation periods have been measured in the Kepler fields, including a substantial fraction of rapid rotators. We use Gaia parallaxes to distinguish photometric binaries (PBs) from single stars on the unevolved lower main sequence, and compare their distribution of rotation properties to those of single stars both with and without Apache Point Observatory Galactic Evolution Experiment (APOGEE) spectroscopic characterization. We find that 59% of stars with 1.5day<P<7day lie 0.3mag above the main sequence, compared with 28% of the full rotation sample. The fraction of stars in the same period range is 1.7{+/-}0.1% of the total sample analyzed for rotation periods. Both the PB fraction and the fraction of rapid rotators are consistent with a population of non-eclipsing short-period binaries inferred from Kepler eclipsing binary data after correcting for inclination. This suggests that the rapid rotators are dominated by tidally synchronized binaries rather than single stars obeying traditional angular momentum evolution. We caution against interpreting rapid rotation in the Kepler field as a signature of youth. Following up on this new sample of 217 candidate tidally synchronized binaries will help further understand tidal processes in stars.
- ID:
- ivo://CDS.VizieR/J/ApJS/225/10
- Title:
- Kinematic analysis of M7-L8 dwarfs
- Short Name:
- J/ApJS/225/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a kinematic analysis of 152 low surface gravity M7-L8 dwarfs by adding 18 new parallaxes (including 10 for comparative field objects), 38 new radial velocities, and 19 new proper motions. We also add low- or moderate-resolution near-infrared spectra for 43 sources confirming their low surface gravity features. Among the full sample, we find 39 objects to be high-likelihood or new bona fide members of nearby moving groups, 92 objects to be ambiguous members and 21 objects that are non-members. Using this age-calibrated sample, we investigate trends in gravity classification, photometric color, absolute magnitude, color-magnitude, luminosity, and effective temperature.
- ID:
- ivo://CDS.VizieR/J/MNRAS/494/2429
- Title:
- Kinematics of nearby young stars
- Short Name:
- J/MNRAS/494/2429
- Date:
- 19 Nov 2021 14:22:11
- Publisher:
- CDS
- Description:
- In the last three decades several hundred nearby members of young stellar moving groups (MGs) have been identified, but there has been less systematic effort to quantify or characterize young stars that do not belong to previously identified MGs. Using a kinematically unbiased sample of 225 lithium-rich stars within 100 pc, we find that only 50+/-10 per cent of young (<=125Myr), low-mass (0.5<M/M_{sun}_<1.0) stars, are kinematically associated with known MGs. Whilst we find some evidence that five of the non-MG stars may be connected with the Lower Centaurus-Crux association, the rest form a kinematically 'hotter' population, much more broadly dispersed in velocity, and with no obvious concentrations in space. The mass distributions of the MG members and non-MG stars are similar, but the non-MG stars may be older on average. We briefly discuss several explanations for the origin of the non-MG population.
- ID:
- ivo://CDS.VizieR/J/AJ/158/20
- Title:
- K-M stars of class I candidate RSGs in Gaia DR2
- Short Name:
- J/AJ/158/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate individual distances and luminosities of a sample of 889 nearby candidate red supergiants (RSGs) with reliable parallaxes ({omega}/{sigma}_{omega}_>4 and RUWE<2.7) from Gaia Data Release 2 (DR2, Cat. I/345). The sample was extracted from the historical compilation of spectroscopically derived spectral types by Skiff (Cat. B/mk), and consists of K-M stars that are listed with class I at least once. The sample includes well-known RSGs from Humphreys (1978ApJS...38..309H), Elias et al. (1985ApJS...57...91E), Jura & Kleinmann (1990ApJS...73..769J), and Levesque et al. (2005ApJ...628..973L). Infrared and optical measurements from the Two Micron All Sky Survey, Catalog of Infrared Observations (CIO), Midcourse Space Experiment, Wide-field Infrared Survey Explorer, MIPSGAL, Galactic Legacy Infrared Midplane Extraordinaire (GLIMPSE), and The Naval Observatory Merged Astrometric Dataset catalogs allow us to estimate the stellar bolometric magnitudes. We analyze the stars in the luminosity versus effective temperature plane and confirm that 43 sources are highly probably RSGs with M_bol_< -7.1 mag. Of the stars in the sample, 43% have masses >7 M_{sun}_. Another ~30% of the sample consists of giant stars.
