- ID:
- ivo://CDS.VizieR/J/A+A/652/A60
- Title:
- Rotation periods for NGC 3532
- Short Name:
- J/A+A/652/A60
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- A very rich cluster intermediate in age between the Pleiades (150Myr) and the Hyades (600Myr) is needed to probe the rotational evolution, especially the transition between fast and slow rotation that occurs between the two ages. We study the rich 300Myr-old open cluster NGC 3532 to probe this important transition and to provide constraints on angular momentum loss. Measuring the rotation periods builds on our prior work of providing spectroscopic membership information for the cluster, and it supports the chromospheric activity measurements of cluster stars that we provide in a companion paper. Using 42d-long photometric time series observations obtained with the Yale 1m telescope at CTIO, we measured rotation periods for members of NGC 3532 and compared them with the predictions of angular momentum evolution models. We directly measured 176 photometric rotation periods for the cluster members. An additional 113 photometric rotation periods were identified using activity information, described fully in the companion paper, resulting in a total sample containing 279 rotation periods for FGKM stars in NGC 3532. The colour-period diagram constructed from this rich data set shows a well-populated and structured slow rotator sequence, and a fast rotator sequence evolved beyond zero-age main sequence age whose stars are in transition from fast to slow rotation. The slow rotator sequence itself is split into slightly slower and faster rotators, a feature we trace to photometric binary status. We also identify an extended slow rotator sequence extending to P~32d, apparently the analogue of the one we previously identified in NGC 2516. We compare our period distribution to rotational isochrones in colour-period space and find that all considered models have certain shortcomings. Using more detailed spin-down models, we evolve the rotation periods of the younger NGC 2516 forward in time and find that the spindown of the models is too aggressive with respect to the slow rotators. In contrast, stars on the evolved fast rotator sequence are not spun down strongly enough by these models. Our observations suggest a shorter crossing time for the rotational gap, one we estimate to be ~80Myr for early-K dwarfs.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/557/L10
- Title:
- Rotation periods of 12000 Kepler stars
- Short Name:
- J/A+A/557/L10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to measure the starspot rotation periods of active stars in the Kepler field as a function of spectral type and to extend reliable rotation measurements from F-, G-, and K-type to M-type stars. Using the Lomb-Scargle periodogram we searched more than 150000 stellar light curves for periodic brightness variations.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A135
- Title:
- RS Cnc IRAM NOEMA interferometric data
- Short Name:
- J/A+A/658/A135
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The latest evolutionary phases of low- and intermediate mass stars are characterized by complex physical processes like turbulence, convection, stellar pulsations, magnetic fields, condensation of solid particles, and the formation of massive outflows that inject freshly produced heavy elements and dust particles into the interstellar medium. By investigating individual objects in detail we wish to analyze and disentangle the effects of the interrelated physical processes on the structure of the wind forming region around these objects. We use the Northern Extended Millimeter Array (NOEMA) to obtain spatially and spectrally resolved observations of the semi-regular Asymptotic Giant Branch star RS Cancri to shed light on the morpho-kinematic structure of its inner, wind forming environment by applying detailed 3-D reconstruction modeling and LTE radiative transfer calculations. We detect 32 lines of 13 molecules and isotopologs (CO, SiO, SO, SO_2_, H_2_O, HCN, PN), including several transitions from vibrationally excited states. HCN, H^13^CN, millimeter vibrationally excited H_2_O, SO, ^34^SO, SO_2_, and PN are detected for the first time in RS Cnc. Evidence for rotation is seen in HCN, SO, SO_2_, and SiO(v=1). From CO and SiO channel maps, we find an inner, equatorial density enhancement, and a bipolar outflow structure with a mass loss rate of 1x10^-7^M_{sun}_/yr for the equatorial region and of 2x10^-7^M_{sun}_/yr for the polar outflows. The ^12^CO/^13^CO ratio is measured to be ~20 on average, 24+/-2 in the polar outflows and 19+/-3 in the equatorial region. We do not find direct evidence of a companion that might explain this kind of kinematic structure, and explore the possibility that a magnetic field might be the cause of it. The innermost molecular gas is influenced by stellar pulsation and possibly by convective cells that leave their imprint on broad wings of certain molecular lines, such as SiO and SO. RS Cnc is one of the few nearby, low mass-loss-rate, oxygen-rich AGB stars with a wind displaying both an equatorial disk and bipolar outflows. Its orientation with respect to the line of sight is particularly favorable for a reliable study of its morpho-kinematics. The mechanism causing early spherical symmetry breaking remains however uncertain, calling for additional high spatial and spectral resolution observations of the emission of different molecules in different transitions, along with a deeper investigation of the coupling among the different physical processes at play.
394. RSGs in the SMC
- ID:
- ivo://CDS.VizieR/J/A+A/639/A116
- Title:
- RSGs in the SMC
- Short Name:
- J/A+A/639/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the most comprehensive red supergiant (RSG) sample for the Small Magellanic Cloud (SMC) to date, including 1239 RSG candidates. The initial sample was derived based on a source catalog for the SMC with conservative ranking. Additional spectroscopic RSGs were retrieved from the literature, and RSG candidates were selected based on the inspection of Gaia and 2MASS color-magnitude diagrams (CMDs). We estimate that there are in total ~1800 or more RSGs in the SMC. We purify the sample by studying the infrared CMDs and the variability of the objects, though there is still an ambiguity between asymptotic giant branch stars (AGBs) and RSGs at the red end of our sample. One heavily obscured target was identified based on multiple near-IR (NIR) and mid-IR (MIR) CMDs. The investigation of color-color diagrams (CCDs) shows that there are fewer RSGs candidates (~4%) showing PAH emission features compared to the Milky Way and LMC (~15%). The MIR variability of RSG sample increases with luminosity. We separate the RSG sample into two subsamples (risky and safe), and identify one M5e AGB star in the risky subsample based on simultaneous inspection of variabilities, luminosities, and colors. The degeneracy of mass loss rate (MLR), variability, and luminosity of the RSG sample is discussed, indicating that most of the targets with high variability are also the bright ones with high MLR. Some targets show excessive dust emission, which may be related to previous episodic mass loss events. We also roughly estimate the total gas and dust budget produced by entire RSG population as ~1.9^+2.4^_-1.1_x10^-6^M_{sun}_/yr in the most conservative case, according to the derived MLR from IRAC1-IRAC4 color. Based on the MIST models, we derive a linear relation between T_eff_ and observed J-Ks color with reddening correction for the RSG sample. By using a constant bolometric correction and this relation, the Geneva evolutionary model is compared with our RSG sample, showing a good agreement and a lower initial mass limit of ~7M_{sun}_ for the RSG population. Finally, we compare the RSG sample in the SMC and the LMC. Despite the incompleteness of LMC sample in the faint end, the result indicates that the LMC sample always shows redder color (except for the IRAC1-IRAC2 and WISE1-WISE2 colors due to CO absorption) and higher variability than the SMC sample, which is likely due to a positive relation between MLR, variability and the metallicity.
- ID:
- ivo://CDS.VizieR/J/A+AS/139/433
- Title:
- RV and vsini of evolved stars
- Short Name:
- J/A+AS/139/433
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Rotational and radial velocities have been measured for about 2000 evolved stars of luminosity classes IV, III, II and Ib covering the spectral region F, G and K. The survey was carried out with the CORAVEL spectrometer. The precision for the radial velocities is better than 0.30km/s, whereas for the rotational velocity measurements the uncertainties are typically 1.0km/s for subgiants and giants and 2.0km/s for class II giants and Ib supergiants. These data will add constraints to studies of the rotational behaviour of evolved stars as well as solid informations concerning the presence of external rotational brakes, tidal interactions in evolved binary systems and on the link between rotation, chemical abundance and stellar activity.
- ID:
- ivo://CDS.VizieR/J/A+A/395/97
- Title:
- RV and vsini of Ib supergiant stars
- Short Name:
- J/A+A/395/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Rotational velocity vsini and mean radial velocity are presented for a sample of 232 Ib supergiant stars covering the spectral region F, G and K. This work is the second part of the large survey carried out with the CORAVEL spectrometer to establish the behavior of the rotation for stars evolving off the main sequence (De Medeiros & Mayor, 1999, Cat. <J/A+AS/139/433>). These data will add constraints to the study of the rotational behavior in evolved stars, as well as solid information concerning tidal interactions in binary systems and on the link between rotation, chemical abundance and activity in stars of intermediate masses.
- ID:
- ivo://CDS.VizieR/J/A+A/561/A126
- Title:
- RV and vsini of southern stars
- Short Name:
- J/A+A/561/A126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Rotational and radial velocities have been measured for 1589 evolved stars of spectral types F, G, and K and luminosity classes IV, III, II, and Ib, based on observations carried out with the CORAVEL spectrometers. The precision in radial velocity is better than 0.30km/s per observation, whereas rotational velocity uncertainties are typically 1.0km/s for subgiants and giants and 2.0km/s for class II giants and Ib supergiants.
- ID:
- ivo://CDS.VizieR/J/AJ/155/159
- Title:
- RVs of the late-T dwarf GL 758 B host star
- Short Name:
- J/AJ/155/159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gl 758 B is a late-T dwarf orbiting a metal-rich Sun-like star at a projected separation of {rho}~1.6" (25 au). We present four epochs of astrometry of this system with NIRC2 at Keck Observatory spanning 2010 to 2017 together with 630 radial velocities (RVs) of the host star acquired over the past two decades from McDonald Observatory, Keck Observatory, and the Automated Planet Finder at Lick Observatory. The RVs reveal that Gl 758 is accelerating with an evolving rate that varies between 2 and 5 m/s/yr, consistent with the expected influence of the imaged companion Gl 758 B. A joint fit of the RVs and astrometry yields a dynamical mass of 42_-7_^+19^ M_Jup_ for the companion with a robust lower limit of 30.5 M_Jup_ at the 4-{sigma} level. Gl 758 B is on an eccentric orbit (e=0.26-0.67 at 95% confidence) with a semimajor axis of a=21.1_-1.3_^+2.7^ au and an orbital period of P=96_-9_^+21^ yr, which takes it within ~9 au from its host star at periastron passage. Substellar evolutionary models generally underpredict the mass of Gl 758 B for nominal ages of 1-6 Gyr that have previously been adopted for the host star. This discrepancy can be reconciled if the system is older - which is consistent with activity indicators and recent isochrone fitting of the host star - or alternatively if the models are systematically overluminous by ~0.1-0.2 dex. Gl 758 B is currently the lowest-mass directly imaged companion inducing a measured acceleration on its host star. In the future, bridging RVs and high-contrast imaging with the next generation of extremely large telescopes and space-based facilities will open the door to the first dynamical mass measurements of imaged exoplanets.
- ID:
- ivo://CDS.VizieR/II/47
- Title:
- Scanner Abundance in late-type evolved stars
- Short Name:
- II/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Abundance parameters have been derived from scanner observations of 229 stars. Observations were made with the Wampler photoelectric spectrum scanner (Wampler, 1966) on Lick Observatory's Crossley and 120inch telescopes. Data reductions were performed at UC Berkeley on the IBM 7094 computer using programs by L.V. Kuhi and B.J. Taylor. The method of reduction and the photometric standard system are described by Spinrad and Taylor (1969AJ.....72..320S). The file "color.dat" (tables 5 and 6 in the publication) gives colors between 3880 and 7400{AA} for program stars and survey stars, normalized so that I(5360)=1000. The file "block.dat" gives the blocking fractions for program stars.
- ID:
- ivo://CDS.VizieR/J/AJ/135/785
- Title:
- SDSS-DR5 low-mass star spectroscopic sample
- Short Name:
- J/AJ/135/785
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic analysis of over 38000 low-mass stars from the Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5). Analysis of this unprecedentedly large sample confirms the previously detected decrease in the fraction of magnetically active stars (as traced by H{alpha} emission) as a function of vertical distance from the Galactic Plane. The magnitude and slope of this effect varies as a function of spectral type. Using simple 1-D dynamical models, we demonstrate that the drop in activity fraction can be explained by thin disk dynamical heating and a rapid decrease in magnetic activity. The timescale for this rapid activity decrease changes according to the spectral type. By comparing our data to the simulations, we calibrate the age-activity relation at each M dwarf spectral type. We also present evidence for a possible decrease in the metallicity as a function of height above the Galactic Plane. In addition to our activity analysis, we provide line measurements, molecular band indices, colors, radial velocities, 3-D space motions and mean properties as a function of spectral type for the SDSS DR5 low-mass star sample.
