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- ID:
- ivo://CDS.VizieR/J/ApJ/731/119
- Title:
- BHB candidates in Sagittarius stream
- Short Name:
- J/ApJ/731/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use a sample of blue horizontal branch (BHB) stars from the Sloan Digital Sky Survey Data Release 7 (Cat. II/294) to explore the structure of the tidal tails from the Sagittarius Dwarf Galaxy. We use a method yielding BHB star candidates with up to ~70% purity from photometry alone. The resulting sample has a distance precision of roughly 5% and can probe distances in excess of 100kpc. Using this sample, we identify a possible extension to the trailing arm at distances of 60-80kpc from the Sun with an estimated significance of at least 3.8{sigma}. Current models predict that a distant "returning" segment of the debris stream should exist, but place it substantially closer to the Sun where no debris is observed in our data. Exploiting the distance precision of our tracers, we estimate the mean line-of-sight thickness of the leading arm to be ~3kpc, and show that the two "bifurcated" branches of the debris stream differ by only 1-2kpc in distance. With a spectroscopic very pure BHB star subsample, we estimate the velocity dispersion in the leading arm, 37km/s, which is in reasonable agreement with models of Sgr disruption. We finally present a sample of high-probability Sgr BHB stars in the leading arm of Sgr, selected to have distances and velocities consistent with Sgr membership, to allow further study.
- ID:
- ivo://CDS.VizieR/J/ApJ/684/1143
- Title:
- BHB candidates in the Milky Way
- Short Name:
- J/ApJ/684/1143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive new constraints on the mass of the Milky Way's dark matter halo, based on 2401 rigorously selected blue horizontal-branch halo stars from SDSS DR6. This sample enables construction of the full line-of-sight velocity distribution at different galactocentric radii. To interpret these distributions, we compare them to matched mock observations drawn from two different cosmological galaxy formation simulations designed to resemble the Milky Way. This procedure results in an estimate of the Milky Way's circular velocity curve to ~60kpc, which is found to be slightly falling from the adopted value of 220km/s at the Sun's location, and implies M(<60kpc)=(4.0+/-0.7)x10^11^M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/AJ/130/1097
- Title:
- BHB stars in Century Survey Galactic Halo Project
- Short Name:
- J/AJ/130/1097
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss a 175{deg}2 spectroscopic survey for blue horizontal branch (BHB) stars in the Galactic halo. We use the Two Micron All Sky Survey (2MASS, <II/246>) and the Sloan Digital Sky Survey (SDSS) to select BHB candidates, and we find that the 2MASS and SDSS color selection is 38% and 50% efficient, respectively, for BHB stars. Our samples include one likely runaway B7 star 6kpc below the Galactic plane.
- ID:
- ivo://CDS.VizieR/J/A+A/374/164
- Title:
- BH Cas VRI differential magnitudes
- Short Name:
- J/A+A/374/164
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New CCD observations of the contact binary system BH Cas are presented in this paper. New times of minima and an ephemeris based on our observations are also given. Complete light curves obtained in the V, R and I filters have been analyzed with the Wilson-Devinney code to derive the geometrical and physical parameters of the system. The final solution leads to a contact configuration (f=~21-22%). We have found that the photometric mass ratio differs from the spectroscopic one by about 13%, a discrepancy which is not uncommon for other W UMa systems. The absolute elements of the system are used to study its evolutionary status. The results show that BH Cas is a fairly evolved W-type W UMa system.
- ID:
- ivo://CDS.VizieR/VII/39A
- Title:
- Bibliography of Surface Photometry of galaxies
- Short Name:
- VII/39A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (adapted from the "Documentation for the Machine-Readable Version of the Detailed bibliography of the surface photometry of galaxies by Lee E. Brotzman and Robert S. Hill (ADC), SASC-T-1-5810-5006-84, July 1984) The bibliography supplies coded information about the methods of observation and reduction, types of photometric data, limiting surface brightness, and the general purpose of each paper for about 650 galaxies and 300 references.
- ID:
- ivo://CDS.VizieR/J/MNRAS/455/2163
- Title:
- BI light curves of DDO210 pulsating variables
- Short Name:
- J/MNRAS/455/2163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have probed the pulsating variable star content of the isolated Local Group dwarf galaxy, DDO210 (Aquarius), using archival Advanced Camera for Surveys/Hubble Space Telescope imaging in the F475W and F814W passbands. We find a total of 32 RR Lyrae stars (24 ab-type; 8 c-type) and 75 Cepheid variables. The mean periods of the ab-type and c-type RR Lyrae stars are calculated to be <Pab>=0.609+/-0.011 and <Pc>=0.359+/-0.025d, respectively. The light-curve properties of the fundamental mode RR Lyrae stars yield a mean metallicity of <[Fe/H]>=-1.63+/-0.11dex for this ancient population, consistent with a recent synthetic colour-magnitude diagram analysis. We find this galaxy to be Oosterhoff-intermediate and lacking in high-amplitude, short-period ab-type RR Lyrae, consistent with behaviour recently observed for many dwarf spheroidals and ultrafaint dwarfs in the Local Group. We find a distance modulus of {mu}=25.07+/-0.12 as determined by the RR Lyrae stars, slightly larger but agreeing with recent distance estimates from the red giant branch tip. We also find a sizable population of Cepheid variables in this galaxy. We provide evidence in favour of most if not all of these stars being short-period classical Cepheids. Assuming all of these stars to be classical Cepheids, we find that most of these Cepheids are ~ 300 Myr old, with the youngest Cepheids being offset from the older Cepheids and the centre of the galaxy. We conclude that this may have resulted from a migration of star formation in DDO210.
- ID:
- ivo://CDS.VizieR/J/A+A/465/965
- Title:
- BI light curves of NGC 2506 variables
- Short Name:
- J/A+A/465/965
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained photometric time-series observations of stars in the open cluster NGC 2506, in order to study pulsating blue stragglers and eclipsing binaries. The data were obtained during a bi-site campaign in early 2005 which involved the Danish 1.54-m telescope at ESO, La Silla, and the Flemish Mercator telescope at La Palma, Spain. Based on these data we increased the number of known variables in NGC 2506 from 5 to 28 through the detection of 3 new pulsating blue stragglers, 15 gamma Doradus stars and 4 new eclipsing binaries, while one variable is of unknown type. We derived orbital periods for two previously known binaries, we performed a tentative mode-identification of the pulsating blue stragglers, and compared B- and I amplitude ratios and phase differences for the gamma Doradus stars to seismic models.
- ID:
- ivo://CDS.VizieR/J/AJ/132/891
- Title:
- Binaries among nearby L dwarfs
- Short Name:
- J/AJ/132/891
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Near-Infrared Camera and Multi-Object Spectrometer NIC1 camera on the Hubble Space Telescope to obtain high angular resolution images of 52 ultracool dwarfs in the immediate solar neighborhood. Nine systems are resolved as binary, with component separations from 1.5 to 15AU. Based on current theoretical models and empirical bolometric corrections, all systems have components with similar luminosities and, consequently, high mass ratios, q>0.8. Limiting analysis to L dwarfs within 20pc, the observed binary fraction is 12%(9-19%). Applying Bayesian analysis to our data set, we derive a mass-ratio distribution that peaks strongly at unity. Modeling the semimajor axis distribution as a logarithmic Gaussian, the best fit is centered at log(a_0_)=0.8AU (a_0_~6.3AU), with a (logarithmic) width of +/-0.3. The current data are consistent with an overall binary frequency of ~24%.
- ID:
- ivo://CDS.VizieR/J/A+A/583/A85
- Title:
- Binaries in beta Pic moving group
- Short Name:
- J/A+A/583/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We look for common proper motion companions to stars of the nearby young {beta} Pictoris moving group. First, we compiled a list of 185 {beta} Pictoris members and candidate members from 35 representative works. Next, we used the Aladin and STILTS virtual observatory tools and the PPMXL proper motion and Washington Double Star catalogues to look for companion candidates. The resulting potential companions were subjects of a dedicated astro-photometric follow-up using public data from all-sky surveys. After discarding 67 sources by proper motion and 31 by colour-magnitude diagrams, we obtained a final list of 36 common proper motion systems. The binding energy of two of them is perhaps too small to be considered physically bound. Of the 36 pairs and multiple systems, eight are new, 16 have only one stellar component previously classified as a {beta} Pictoris member, and three have secondaries at or below the hydrogen-burning limit. Sixteen stars are reported here for the first time as moving group members. The unexpected large number of high-order multiple systems, 12 triples and two quadruples among 36 systems, may suggest a biased list of members towards close binaries or an increment of the high-order-multiple fraction for very wide systems.
