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- ID:
- ivo://CDS.VizieR/J/AJ/107/2240
- Title:
- Proper motion stars survey. XII.
- Short Name:
- J/AJ/107/2240
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report new photometry and radial velocities for almost 500 stars from the Lowell Proper Motion Catalog. We combine these results with our prior sample and rederive stellar temperatures based on the photometry, reddening, metallicities (using Chi^2 matching of our 22,500 low S/N high resolution echelle spectra with a grid of synthetic spectra), distances, space motions, and Galactic orbital parameters for 1269 (kinematics) and 1261 (metallicity) of the 1464 stars in the complete survey. The frequency of spectroscopic binaries for the metal-poor ([m/H]<=-1.2) stars with periods shorter than 3000 days is at least 15%. The spectroscopic binary frequency for metal-rich stars ([m/H]>-0.5) appears to be lower, about 9%, but this may be a selection effect. We also discuss special classes of stars, including treatment of the double-lined spectroscopic binaries, and identification of subgiants. Four possible new members of the class of field blue stragglers are noted. We point out the detection of three possible new white dwarfs, six broad-lined (binary) systems, and discuss briefly the three already known nitrogen-rich halo dwarfs.
- ID:
- ivo://CDS.VizieR/J/A+A/629/A134
- Title:
- Radiative contribution from stripped stars
- Short Name:
- J/A+A/629/A134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stars stripped of their envelopes from interaction with a binary companion emit a significant fraction of their radiation as ionizing photons. They are potentially important stellar sources of ionizing radiation, however, they are still often neglected in spectral synthesis simulations or simulations of stellar feedback. In anticipating the large datasets of galaxy spectra from the upcoming James Webb Space Telescope, we modeled the radiative contribution from stripped stars by using detailed evolutionary and spectral models. We estimated their impact on the integrated spectra and specifically on the emission rates of HI-, HeI-, and HeII-ionizing photons from stellar populations. We find that stripped stars have the largest impact on the ionizing spectrum of a population in which star formation halted several Myr ago. In such stellar populations, stripped stars dominate the emission of ionizing photons, mimicking a younger stellar population in which massive stars are still present. Our models also suggest that stripped stars have harder ionizing spectra than massive stars. The additional ionizing radiation, with which stripped stars contribute affects observable properties that are related to the emission of ionizing photons from stellar populations. In co-eval stellar populations, the ionizing radiation from stripped stars increases the ionization parameter and the production efficiency of hydrogen ionizing photons. They also cause high values for these parameters for about ten times longer than what is predicted for massive stars. The effect on properties related to non-ionizing wavelengths is less pronounced, such as on the ultraviolet continuum slope or stellar contribution to emission lines. However, the hard ionizing radiation from stripped stars likely introduces a characteristic ionization structure of the nebula, which leads to the emission of highly ionized elements such as O^2+^ and C^3+^. We, therefore, expect that the presence of stripped stars affects the location in the BPT diagram and the diagnostic ratio of OIII to OII nebular emission lines. Our models are publicly available through CDS database and on the STARBURST99 website.
- ID:
- ivo://CDS.VizieR/J/AJ/156/98
- Title:
- Runaway stars in the 30 Doradus region of the LMC
- Short Name:
- J/AJ/156/98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of relative proper motions for 368787 stars in the 30 Doradus region of the Large Magellanic Cloud (LMC), based on a dedicated two-epoch survey with the Hubble Space Telescope and supplemented with proper motions from our pilot archival study. We demonstrate that a relatively short epoch difference of three years is sufficient to reach a level of precision of ~0.1 mas/yr or better. A number of stars with relative proper motions exceeding a 3{sigma} error threshold represent a mixture of Milky Way denizens and 18 potential LMC runaway stars. Based upon 183 VFTS OB stars with the best proper motions, we conclude that none of them moves faster than ~0.3 mas/yr in each coordinate-equivalent to ~70 km/s. Among the remaining 351 VFTS stars with less accurate proper motions, only one candidate OB runaway can be identified. We rule out any OB star in our sample moving at a tangential velocity exceeding ~120 km/s. The most significant result of this study is finding 10 stars over a wide range of masses that appear to have been ejected from the massive star cluster R136 in the tangential plane to angular distances from 35" out to 407", equivalent to 8-98 pc. The tangential velocities of these runaways appear to be correlated with apparent magnitude, indicating a possible dependence on the stellar mass. Lastly, a comparison to proper motions from Gaia DR 2 shows that for several relatively bright stars the DR 2 has an unexpected scatter that cannot be accounted for by the formal errors.
- ID:
- ivo://CDS.VizieR/J/AJ/136/2050
- Title:
- SEGUE stellar parameter pipeline. II.
- Short Name:
- J/AJ/136/2050
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We validate the accuracy and precision of the current SEGUE (Sloan Extension for Galactic Understanding and Exploration) Stellar Parameter Pipeline (SSPP), which determines stellar atmospheric parameters (effective temperature, surface gravity, and metallicity) and radial velocities (RVs), by comparing these estimates for selected members of three globular clusters (M 13, M 15, and M 2) and two open clusters (NGC 2420 and M 67) to the literature values. Spectroscopic and photometric data obtained during the course of the original Sloan Digital Sky Survey (SDSS-I) and its first extension (SDSS-II/SEGUE) are used to determine atmospheric parameter and RV estimates for stars in these clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/136/2070
- Title:
- SEGUE stellar parameter pipeline. III.
- Short Name:
- J/AJ/136/2070
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report high-resolution spectroscopy of 125 field stars previously observed as part of the Sloan Digital Sky Survey and its program for Galactic studies, the Sloan Extension for Galactic Understanding and Exploration (SEGUE). These spectra are used to measure radial velocities and to derive atmospheric parameters, which we compare with those reported by the SEGUE Stellar Parameter Pipeline (SSPP). The SSPP obtains estimates of these quantities based on SDSS ugriz photometry and low-resolution (R~2000) spectroscopy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/1131
- Title:
- Selection function of Milky Way field stars
- Short Name:
- J/MNRAS/460/1131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Gaia-ESO Survey was designed to target all major Galactic components (i.e. bulge, thin and thick discs, halo and clusters), with the goal of constraining the chemical and dynamical evolution of the Milky Way. This paper presents the methodology and considerations that drive the selection of the targeted, allocated and successfully observed Milky Way field stars. The detailed understanding of the survey construction, specifically the influence of target selection criteria on observed Milky Way field stars is required in order to analyse and interpret the survey data correctly. We present the target selection process for the Milky Way field stars observed with Very Large Telescope/Fibre Large Array Multi Element Spectrograph and provide the weights that characterize the survey target selection. The weights can be used to account for the selection effects in the Gaia-ESO Survey data for scientific studies. We provide a couple of simple examples to highlight the necessity of including such information in studies of the stellar populations in the Milky Way.
- ID:
- ivo://CDS.VizieR/J/AJ/161/74
- Title:
- SMASH DR2. 197 SMASH fields
- Short Name:
- J/AJ/161/74
- Date:
- 19 Jan 2022 09:37:25
- Publisher:
- CDS
- Description:
- The Large and Small Magellanic Clouds (LMC and SMC) are the largest satellite galaxies of the Milky Way and close enough to allow for a detailed exploration of their structure and formation history. The Survey of the MAgellanic Stellar History (SMASH) is a community Dark Energy Camera (DECam) survey of the Magellanic Clouds using ~50 nights to sample over ~2400deg^2^ centered on the Clouds at ~20% filling factor (but with contiguous coverage in the central regions) and to depths of ~24th mag in ugriz. The primary goals of SMASH are to map out the extended stellar peripheries of the Clouds and uncover their complicated interaction and accretion history as well as to derive spatially resolved star formation histories of the central regions and create a "movie" of their past star formation. Here we announce the second SMASH public data release (DR2), which contains all 197 fully calibrated DECam fields including the main body fields in the central regions. The DR2 data are available through the Astro Data Lab hosted by the NSF's National Optical-Infrared Astronomy Research Laboratory. We highlight three science cases that make use of the SMASH DR2 data and will be published in the future: (1) preliminary star formation histories of the LMC, (2) the search for Magellanic star clusters using citizen scientists, and, (3) photometric metallicities of Magellanic Cloud stars using the DECam u-band.
- ID:
- ivo://CDS.VizieR/J/AJ/154/199
- Title:
- SMASH: Survey of the MAgellanic Stellar History
- Short Name:
- J/AJ/154/199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Large and Small Magellanic Clouds are unique local laboratories for studying the formation and evolution of small galaxies in exquisite detail. The Survey of the MAgellanic Stellar History (SMASH) is an NOAO community Dark Energy Camera (DECam) survey of the Clouds mapping 480 deg^2^ (distributed over ~2400 square degrees at ~20% filling factor) to ~24th mag in ugriz. The primary goals of SMASH are to identify low surface brightness stellar populations associated with the stellar halos and tidal debris of the Clouds, and to derive spatially resolved star formation histories. Here, we present a summary of the survey, its data reduction, and a description of the first public Data Release (DR1). The SMASH DECam data have been reduced with a combination of the NOAO Community Pipeline, the PHOTRED automated point-spread-function photometry pipeline, and custom calibration software. The astrometric precision is ~15 mas and the accuracy is ~2 mas with respect to the Gaia reference frame. The photometric precision is ~0.5%-0.7% in griz and ~1% in u with a calibration accuracy of ~1.3% in all bands. The median 5{sigma} point source depths in ugriz are 23.9, 24.8, 24.5, 24.2, and 23.5 mag. The SMASH data have already been used to discover the Hydra II Milky Way satellite, the SMASH 1 old globular cluster likely associated with the LMC, and extended stellar populations around the LMC out to R~18.4 kpc. SMASH DR1 contains measurements of ~100 million objects distributed in 61 fields. A prototype version of the NOAO Data Lab provides data access and exploration tools.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A110
- Title:
- Spectroscopic membership for NGC 3532
- Short Name:
- J/A+A/622/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 3532 is an extremely rich open cluster embedded in the Galactic disc, hitherto lacking a comprehensive, documented membership list. We provide membership probabilities from new radial velocity observations of solar-type and low-mass stars in NGC 3532, in part as a prelude to a subsequent study of stellar rotation in the cluster. Using extant optical and infra-red photometry we constructed a preliminary photometric membership catalogue, consisting of 2230 dwarf and turn-off stars. We selected 1060 of these for observation with the AAOmega spectrograph at the 3.9m Anglo-Australian Telescope and 391 stars for observations with the Hydra-South spectrograph at the 4m Victor Blanco Telescope, obtaining spectroscopic observations over a decade for 145 stars. We measured radial velocities for our targets through cross-correlation with model spectra and standard stars, and supplemented them with radial velocities for 433 additional stars from the literature. We also measured logg, Teff, and [Fe/H] from the AAOmega spectra. The radial velocity distribution emerging from the observations is centred at 5.43+/-0.04km/s and has a width (standard deviation) of 1.46km/s. Together with proper motions from Gaia DR2 we find 660 exclusive members, of which five are likely binary members. The members are distributed across the whole cluster sequence, from giant stars to M dwarfs, making NGC~3532 one of the richest Galactic open clusters known to date, on par with the Pleiades. From further spectroscopic analysis of 153 dwarf members we find the metallicity to be marginally sub-solar, with [Fe/H]=-0.07+/-0.10. We confirm the extremely low reddening of the cluster, E_B-V_=0.034+/-0.012mag, despite its location near the Galactic plane. Exploiting trigonometric parallax measurements from Gaia DR2 we find a distance of 484^+35^_-30_pc [(m-M)_0_=8.42+/-0.14mag]. Based on the membership we provide an empirical cluster sequence in multiple photometric passbands. A comparison of the photometry of the measured cluster members with several recent model isochrones enables us to confirm the 300Myr cluster age. However, all of the models evince departures from the cluster sequence in particular regions, especially in the lower mass range.
