- ID:
- ivo://CDS.VizieR/J/ApJS/94/687
- Title:
- Old stellar populations. V.
- Short Name:
- J/ApJS/94/687
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Twenty-one optical absorption features, 11 of which have been previously defined, are automatically measured in a sample of 460 stars. Following Gorgas et al., the indices are summarized in fitting functions that give index strengths as functions of stellar temperature, gravity, and [Fe/H]. This project was carried out with the purpose of predicting index strengths in the integrated light of stellar populations of different ages and metallicities, but the data should be valuable for stellar studies in the Galaxy as well. Several of the new indices appear to be promising indicators of metallicity for old stellar populations. A complete list of index data and atmospheric parameters is available in computer-readable form.
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- ID:
- ivo://CDS.VizieR/J/other/RMxAA/56.139
- Title:
- On the evolution of angular momentum
- Short Name:
- J/other/RMxAA/56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Selecting the best quality data, I find that nearly all 0.5 to 1.2M_{sun}_ main sequence stars converge to a single rotational mass dependent sequence after 750Myr; when the mass is larger than 0.8M_{sun}_, most of them converge in ~120Myr. If stars rotate as rigid bodies, the angular momentum of the vast majority is within clearly outlined bounds. The lower boundary defines a terminal main sequence rotational isochrone, the upper one coincides with slow rotators from the Pleiades and stars from Praesepe delineate a third one. Mass dependent exponential relationships between angular momentum and age are determined from these isochrones. Age estimates based on the angular momentum, are acceptable in middle aged stars older than 750Myr and more massive than 0.6-0.7M_{sun}_. The evolution of the Rossby number indicates that the Parker dynamo may cease early on in stars where M/M_{sun}_>=1.1. An empirical formula for the torque, an idealized model for it and a relation between rotational period and magnetic field, lead to a formula for the evolution of the mass loss rate, predicting that the present solar rate is close to a minimum and that it was around five times more vigorous when life on Earth started.
- ID:
- ivo://CDS.VizieR/J/A+A/338/1066
- Title:
- Optical Spectra of DENIS Brown Dwarf Candidate
- Short Name:
- J/A+A/338/1066
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical spectra for candidate brown dwarfs from the DENIS Mini-survey are provided. These are the spectra used to in Figure 1 of the paper.
- ID:
- ivo://CDS.VizieR/J/A+A/563/A63
- Title:
- Optical spectra of new low-excitation PNs
- Short Name:
- J/A+A/563/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present mid-resolution spectroscopic observations of four new planetary nebula (PN) candidates selected from the INT/WFC Photometric H-alpha Survey of the Northern Galactic Plane (IPHAS) and Deep Sky Hunter (DSH) catalogues. The PN status of these objects was confirmed by mid-resolution spectra. Based on the locations of these objects in the log(H-alpha/[NII]) versus log (H-alpha/[SII]) diagnostic diagram, these sources are evolved low- excitation PNs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/455/2216
- Title:
- Outer bulge O-rich Mira's JHKL photometry
- Short Name:
- J/MNRAS/455/2216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report periods and JHKL observations for 643 oxygen-rich Mira variables found in two outer bulge fields at b=-7{deg} and l=+/-8{deg} and combine these with data on 8057 inner bulge Miras from the OGLE, Macho and 2MASS surveys, which are concentrated closer to the Galactic centre. Distance moduli are estimated for all these stars. Evidence is given showing that the bulge structure is a function of age. The longer period Miras (LogP>2.6, age~5Gyr and younger) show clear evidence of a bar structure inclined to the line of sight in both the inner and outer regions. The distribution of the shorter period (metal-rich globular cluster age) Miras, appears spheroidal in the outer bulge. In the inner region these old stars are also distributed differently from the younger ones and possibly suggest a more complex structure. These data suggest a distance to the galactic centre R_0_, of 8.9kpc, with an estimated uncertainty of ~0.4kpc. The possible effect of helium enrichment on our conclusions is discussed.
- ID:
- ivo://CDS.VizieR/J/ApJ/602/L117
- Title:
- Oxygen in Pleiades and M34 dwarfs
- Short Name:
- J/ApJ/602/L117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze the high-excitation O I {lambda}7774 triplet in high-resolution, moderate signal-to-noise ratio spectra of 15 Pleiades and eight M34 open cluster dwarfs over the effective temperature range of 5048-6172K. Relative O abundances have been derived using model atmospheres interpolated from four different sets of ATLAS9 grids. In contrast to existing non-LTE (NLTE) predictions, a dramatic increase in the O I triplet abundance with decreasing temperature is seen for both clusters, regardless of the atmospheric model. S I abundances of three Pleiades stars derived from the high-excitation {lambda}6053 feature mimic the O I abundance behavior. O abundances have also been derived from the [O I] {lambda}6300 feature in three Pleiades stars; the abundances exhibit a much lower mean value than do the cool dwarf triplet results. Inasmuch as the [O I] abundances are presumed to be free from NLTE effects, their mean values ([O/H]_6300_=+0.14) provide the current best estimate of the Pleiades O abundance. Spreads in [O/H]_Trip_ at a given temperature are also seen in both clusters; no correlation is found between the spreads and the chromospheric emission measures.
- ID:
- ivo://CDS.VizieR/J/A+A/613/A40
- Title:
- PACS photometry of FIR faint stars
- Short Name:
- J/A+A/613/A40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our aims are to determine flux densities and their photometric accuracy for a set of seventeen stars that range in flux from intermediately bright (<~2.5Jy) to faint (>~5mJy) in the far-infrared (FIR). We also aim to derive signal-to-noise dependence with flux and time, and compare the results with predictions from the Herschel exposure-time calculation tool. We obtain aperture photometry from Herschel-PACS high-pass-filtered scan maps and chop/nod observations of the faint stars. The issues of detection limits and sky confusion noise are addressed by comparison of the field-of-view at different wavelengths, by multi-aperture photometry, by special processing of the maps to preserve extended emission, and with the help of large-scale absolute sky brightness maps from AKARI. This photometry is compared with flux-density predictions based on photospheric models for these stars. We obtain a robust noise estimate by fitting the flux distribution per map pixel histogram for the area around the stars, scaling it for the applied aperture size and correcting for noise correlation.
- ID:
- ivo://CDS.VizieR/J/A+A/559/A43
- Title:
- Pan-STARRS1 (PS1) observations of the Hyades
- Short Name:
- J/A+A/559/A43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed a kinematic and photometric search for Hyades members using the PPMXL and Pan-STARRS1 sky surveys, up to 30pc from the cluster centre, down to masses of 0.1M_{sun}_. We exclude some candidates previously identified in Roeser et al. (2011, Cat. J/A+A/531/A92). We discovered 62 new Hyades member candidates with velocity perpendicular to the Hyades motion up to 4km/s. They have mass estimates between 0.43 and 0.09M_{sun}_, for a total mass of 10M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/A+A/523/A58
- Title:
- PDF Atlas and spectra of FeH molecule in LHS 2
- Short Name:
- J/A+A/523/A58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an atlas for the iron-hydride molecule (FeH) in the z-range (990nm to 1076.6nm). We used high-resolution CRIRES spectra of the M-dwarf GJ1002, which is an ideal target for the investigation of FeH, because it is only very slow rotating (<3km/s) and exhibits only weak magnetic fields. The identified lines stem mainly from the (0-0) and (1-1) vibronic transitions, but also from the (1-0), (2-1), (2-2), (3-2), and (4-3) transitions. For the confirmation of the identifications, we used means of statistic and cross-correlation as well as the line intensities. We corrected the theoretical positions if needed and scaled the line intensities till they match the observations.
- ID:
- ivo://CDS.VizieR/J/other/Ap/64.27
- Title:
- Periodic variables in Catalina and LINEAR
- Short Name:
- J/other/Ap/64.27
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- In this study we continue spectral class determinations for large number of optically faint periodic variables taken from the Catalina Surveys Data Release 1 (CSDR1)and LINEAR data sets. Spectral classes and physical parameters are presented for 1184 periodic variables with periods P>=10 days, taken from modern large sky area spectroscopic and photometric databases, including LAMOST(Large Sky Area Multi-Object Fiber Spectroscopic Telescope), SDSS(Sloan Digital Sky Survey), the Hamburg Quasar Survey(HQS)m the Hamburg /ESO Survey (HES), and Gaia Data Release 2 (DR2). In Gaia DR2 catalogue, luminosities are presented for 276 objects and radial velocities (RV) for 108. Spectral classes were confirmed for more than 650 objects. The majority of the variables are found to be F, G, K, M dwarfs and giants, a few dozen carbon (C) stars (N-type Asymptotic Giant Branch (AGB) stars), and a few S stars. Some periodic variables are blue objects, such as B and A stars. The periods are in the range 10<=P<=1504 days and Catalina magnitudes in range 11.5<=V<=20.0mag. Finding new and faint evolved AGB stars in the halo of our Galaxy is the first priority. A catalogue containing multi-parameter data for 1184 periodic variables from modern astronomical databases has been generated.
