- ID:
- ivo://CDS.VizieR/J/A+AS/126/401
- Title:
- M 31 Cepheids periods
- Short Name:
- J/A+AS/126/401
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cepheid variables can be used for more than just a distance indicator. Since the age can be determined from the period, they can be used to trace the star formation history of a galaxy. We have identified 130 new Cepheid variable candidates in M 31, particularly along the spiral arm regions in the north-east of the galaxy. These areas had not been searched for Cepheids in the previous study by Baade and collaborators. The contamination of our sample by other types of variables is low (<3%). For V<21, the completeness is =~53%. These Cepheids will be used to explore the star formation history in M 31.
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- ID:
- ivo://CDS.VizieR/VI/156
- Title:
- M-dwarf Lum-Temp-Radius relationships
- Short Name:
- VI/156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- There is growing evidence that M-dwarf stars suffer radius inflation when compared to theoretical models, suggesting that models are missing some key physics required to completely describe stars at effective temperatures (TSED) less than about 4000K. The advent of Gaia DR2 distances finally makes available large datasets to determine the nature and extent of this effect.We employ an all-sky sample, comprising of >15000 stars, to determine empirical relation-ships between luminosity, temperature and radius.This is accomplished using only geometric distances and multiwave-band photometry, by utilising a modified spectral energy distribution fitting method. The radii we measure show an inflation of 3-7% compared to models, but nomore than a 1-2% intrinsic spread in the inflated sequence. We show that we are currently able to determine M-dwarf radii to an accuracy of 2.4% using our method. However, we determine that this is limited by the precision of metallicity measurements, which contribute 1.7% to the measured radius scatter. We also present evidence that stellar magnetism is currently unable to explain radius inflation in M-dwarfs.
- ID:
- ivo://CDS.VizieR/J/ApJS/173/673
- Title:
- M dwarf UV flares in GALEX
- Short Name:
- J/ApJS/173/673
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the preliminary results from implementing a new software tool that enables inspection of time-tagged photon data for the astronomical sources contained within individual GALEX ultraviolet (UV) images of the sky. We have inspected the photon data contained within 1802 GALEX images to reveal rapid, short-term (<~500s) UV source variability in the form of stellar "flares." The mean associated change in near-UV (NUV) magnitude due to this flaring activity is 2.7+/-0.3mag. A list of 49 new UV variable star candidates is presented (associated with 52 separate flare events), together with their associated Sloan Digital Sky Survey (SDSS) photometric magnitudes. From these data we can associate the main source of these UV flare events with magnetic activity on M dwarf stars. Photometric parallaxes have been determined for 32 of these sources, placing them at distances ranging from approximately 25 to 1000pc. The average UV flare energy for these flare events is 2.5x10^30^ergs, which is of a similar energy to that of U-band, X-ray, and EUV flares observed on many local M dwarf stars. We have found that stars of classes M0 to M5 flare with energies spanning a far larger range and with an energy approximately 5 times greater than those of later (M6 to M8) spectral type.
- ID:
- ivo://CDS.VizieR/J/AJ/134/2340
- Title:
- Membership of Praesepe and Coma Berenices clusters
- Short Name:
- J/AJ/134/2340
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a stellar membership survey of the nearby open clusters Praesepe and Coma Berenices. We have combined archival survey data from the SDSS, 2MASS, USNOB1.0, and UCAC-2.0 surveys to compile proper motions and photometry for ~5 million sources over 300{deg}^2^. Of these sources, 1010 stars in Praesepe and 98 stars in Coma Ber are identified as candidate members with probability >80%; 442 and 61 are identified as high-probability candidates for the first time. We estimate that this survey is >90% complete across a wide range of spectral types (F0-M5 in Praesepe, F5-M6 in Coma Ber). We have also investigated the stellar mass dependence of each cluster's mass and radius in order to quantify the role of mass segregation and tidal stripping in shaping the present-day mass function and spatial distribution of stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/371/1793
- Title:
- Metallicity calibrations for UBV photometry
- Short Name:
- J/MNRAS/371/1793
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Calibrations are presented here for metallicity ([Fe/H]) in terms of the ultraviolet excess, [{Delta}(U-B) at B-V=0.6, hereafter D0.6], and also for the absolute visual magnitude (M_V_) and its difference with respect to the Hyades ({Delta}M^H^_V_) in terms of D0.6 and (B-V), making use of high-resolution spectroscopic abundances from the literature and Hipparcos parallaxes.
- ID:
- ivo://CDS.VizieR/J/AJ/158/75
- Title:
- Mid-type M dwarfs planet occurrence rates
- Short Name:
- J/AJ/158/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Previous studies of planet occurrence rates largely relied on photometric stellar characterizations. In this paper, we present planet occurrence rates for mid-type M dwarfs using spectroscopy, parallaxes, and photometry to determine stellar characteristics. Our spectroscopic observations have allowed us to constrain spectral type, temperatures, and, in some cases, metallicities for 337 out of 561 probable mid-type M dwarfs in the primary Kepler field. We use a random forest classifier to assign a spectral type to the remaining 224 stars. Combining our data with Gaia parallaxes, we compute precise (~3%) stellar radii and masses, which we use to update planet parameters and occurrence rates for Kepler mid-type M dwarfs. Within the Kepler field, there are seven M3 V to M5 V stars that host 13 confirmed planets between 0.5 and 2.5 Earth radii and at orbital periods between 0.5 and 10 days. For this population, we compute a planet occurrence rate of 1.19_-0.49_^+0.70^ planets per star. For M3 V, M4 V, and M5 V, we compute planet occurrence rates of 0.86_-0.68_^+1.32^, 1.36_-1.02_^+2.30^, and 3.07_-2.49_^+5.49^ planets per star, respectively.
- ID:
- ivo://CDS.VizieR/J/MNRAS/289/745
- Title:
- Mira variables in NGC 6749 field
- Short Name:
- J/MNRAS/289/745
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present V, I photometry of the loose star cluster NGC 6749, and for the first time colour-magnitude diagrams are provided. We confirm that it is a globular cluster and its blue horizontal branch indicates that it is metal-poor. We derive a reddening of E(B-V)=1.39+/-0.04 and a distance from the Sun d_{sun}_=7.3+/-0.9kpc (assuming a total-to-selective absorption R=3.4). The cluster is projected very close to the Galactic plane, and the derived distance implies a Galactic coordinate Z~-300pc. It is thus a halo globular cluster located close to the disc plane. We also discuss the properties of 78 newly discovered long-period variable stars, of which 75 are Miras, projected within 1{deg} of the cluster centre. The variables do not appear to be associated with the globular cluster. From their periods, most of them belong to the metal-rich disc or bulge stellar populations.
- ID:
- ivo://CDS.VizieR/J/ApJS/252/32
- Title:
- MIR outbursts in nearby SDSS gal. (MIRONG). I.
- Short Name:
- J/ApJS/252/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical time-domain astronomy has grown rapidly in the past decade, but the dynamic infrared sky is rarely explored. Aiming to construct a sample of mid-infrared outbursts in nearby galaxies (MIRONG), we have conducted a systematical search of low-redshift (z<0.35) Sloan Digital Sky Survey spectroscopic galaxies that have experienced recent mid-infrared (MIR) flares using their Wide-field Infrared Survey Explorer (WISE) light curves. A total of 137 galaxies have been selected by requiring a brightening amplitude of 0.5mag in at least one WISE band with respect to their quiescent phases. Only a small fraction (10.9%) has corresponding optical flares. Except for the four supernovae (SNe) in our sample, the MIR luminosities of the remaining sources (L_4.6{mu}m_>10^42^erg/s) are markedly brighter than known SNe, and their physical locations are very close to the galactic center (median <0.1"). Only four galaxies are radio-loud, indicating that synchrotron radiation from relativistic jets could contribute to MIR variability. We propose that these MIR outbursts are dominated by the dust echoes of transient accretion onto supermassive black holes, such as tidal disruption events (TDEs) and turn-on (changing-look) active galactic nuclei. Moreover, the inferred peak MIR luminosity function is generally consistent with the X-ray and optical TDEs at the high end, albeit with large uncertainties. Our results suggest that a large population of transients has been overlooked by optical surveys, probably due to dust obscuration or intrinsically optical weakness. Thus, a search in the infrared band is crucial for us to obtain a panoramic picture of nuclear outburst. The multiwavelength follow-up observations of the MIRONG sample are in progress and will be presented in a series of subsequent papers.
- ID:
- ivo://CDS.VizieR/J/ApJ/492/62
- Title:
- M87 planetary nebulae
- Short Name:
- J/ApJ/492/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a wide-field [O III] {lambda}5007 survey for planetary nebulae (PN) in M87 and its surrounding halo. In all, we identify 338 PN candidates in a 16'x16' field around the galaxy; 187 of these objects are in a statistical sample that extends to m5007=27.15.
- ID:
- ivo://CDS.VizieR/J/ApJS/107/19
- Title:
- MRC/1Jy Radio source survey. I.
- Short Name:
- J/ApJS/107/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first in a series of papers discussing the properties of a complete set of radio sources selected near S408=1Jy. We present optical or infrared identifications for a sample of 452 radio galaxies. The sources were selected from the 408MHz Molonglo Reference Catalog, restricted only by flux density and position on the sky, as follows: S408>0.95Jy and -30<decl.(1950)<-20, and 9h20m<R.A.(1950)<14h4m or 20h20m<R.A.(1950)<6h14m. This complete sample, the MRC/1 Jy survey, contains 558 radio galaxies or quasars, of which six are occulted by bright stars or galaxies and two are multiple confused sources. Of the remaining 550 sources, 527, or 96%, are identified to an r magnitude of 25, and eight additional sources are identified to K=19. Of the 17 unocculted objects that remain unidentified, 15 are sources for which we have either poor radio maps or inadequate optical/IR images. This paper presents finding charts and astrometric positions for the 452 sources that are not identified as either quasars or BL Lacertae objects. Magnitudes in the r passband accurate to typically 0.1mag are given for 353 of the radio galaxy identifications. Redshifts for 268 of the galaxies are also listed; these have been derived from 450 spectroscopic observations. The radio observations, quasar and BL Lac identifications, spectroscopy, and near-IR images will be presented in subsequent papers in this series.
