- ID:
- ivo://CDS.VizieR/J/MNRAS/453/2220
- Title:
- Early-type Sco-Cen members with literature RVs
- Short Name:
- J/MNRAS/453/2220
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the serendipitous discovery of several young mid-M stars found during a search for new members of the 30-40Myr-old Octans Association. Only one of the stars may be considered a possible Octans(-Near) member. However, two stars have proper motions, kinematic distances, radial velocities, photometry and LII {lambda}6708 measurements consistent with membership in the 8-10Myr-old TW Hydrae Association. Another may be an outlying member of TW Hydrae but has a velocity similar to that predicted by membership in Octans. We also identify two new lithium-rich members of the neighbouring Scorpius-Centaurus OB Association (Sco-Cen). Both exhibit large 12 and 22{mu}m excesses and strong, variable H{alpha} emission which we attribute to accretion from circumstellar discs. Such stars are thought to be incredibly rare at the ~16Myr median age of Sco-Cen and they join only one other confirmed M-type and three higher mass accretors outside of Upper Scorpius. The serendipitous discovery of two accreting stars hosting large quantities of circumstellar material may be indicative of a sizeable age spread in Sco-Cen, or further evidence that disc dispersal and planet formation time-scales are longer around lower mass stars. To aid future studies of Sco-Cen, we also provide a newly compiled catalogue of 305 early-type Hipparcos members with spectroscopic radial velocities sourced from the literature.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/342/671
- Title:
- Early-type spiral galaxies kinematics
- Short Name:
- J/A+A/342/671
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the stellar and ionized-gas velocity curves and velocity-dispersion profiles along the major axis for six early-type spiral galaxies. Two of these galaxies, namely NGC 2179 and NGC 2775, are particularly suited for the study of dark matter halos. Using their luminosity profiles and modeling their stellar and gaseous kinematics, we derive the mass contributions of the luminous and the dark matter to the total potential. In NGC 2179 we find that the data (measured out to about the optical radius R_opt_) unambiguously require the presence of a massive dark halo. For the brighter and bigger object NGC 2775, we can rule out a significant halo contribution at radii R<~0.6R_opt_. Although preliminary, these results agree with the familiar mass distribution trend known for late-type spirals of comparable mass.
- ID:
- ivo://CDS.VizieR/J/A+AS/139/231
- Title:
- Early-type stars towards the Galactic Centre
- Short Name:
- J/A+AS/139/231
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have begun a search for early-type stars towards the galactic centre which are potentially young objects situated within the inner few kiloparsecs of the disk. U and V (or I) band photographic photometry from the UK Schmidt Telescope has been obtained to identify the bluest candidates in nineteen Schmidt fields (centred close to the galactic centre). We have spectroscopically observed these targets for three fields with the FLAIR multi-fibre system to determine their spectral types. In particular, ten early B-type stars have been identified and equivalent width measurements of their Balmer and HeI lines have been used to estimate atmospheric parameters. These early-type objects have magnitudes in the range 11.5=<V<=16.0, and our best estimates of their distance (given probable highly variable reddening in this direction together with errors in the plate photometry) suggest that some of them originated close to (i.e R_g_<3kpc), or even beyond the galactic centre. Future high-resolution spectroscopy of these stars will provide reliable atmospheric parameters and element abundances, in order to map the current chemical composition of the inner galaxy.
- ID:
- ivo://CDS.VizieR/J/A+A/626/A119
- Title:
- EBLM J2349-32 photometry, RV and spectra
- Short Name:
- J/A+A/626/A119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Some M-dwarfs around F-/G-type stars have been measured to be hotter and larger than predicted by stellar evolution models. Inconsistencies between observations and models need to be addressed with more mass, radius, and luminosity measurements of low-mass stars to test and refine evolutionary models. Our aim is to measure the masses, radii and ages of the stars in five low-mass eclipsing binary systems discovered by the WASP survey. We used WASP photometry to establish eclipse-time ephemerides and to obtain initial estimates for the transit depth and width. Radial velocity measurements were simultaneously fitted with follow-up photometry to find the best-fitting orbital solution. This solution was combined with measurements of atmospheric parameters to interpolate evolutionary models and estimate the mass of the primary star, and the mass and radius of the M-dwarf companion. We assess how the best fitting orbital solution changes if an alternative limb-darkening law is used and quantify the systematic effects of unresolved companions. We also gauge how the best-fitting evolutionary model changes if different values are used for the mixing length parameter and helium enhancement. We report the mass and radius of five M-dwarfs and find little evidence of inflation with respect to evolutionary models. The primary stars in two systems are near the "blue hook" stage of their post sequence evolution, resulting in two possible solutions for mass and age. We find that choices in helium enhancement and mixing-length parameter can introduce an additional 3-5% uncertainty in measured M-dwarf mass. Unresolved companions can introduce an additional 3-8% uncertainty in the radius of an M-dwarf, while the choice of limb-darkening law can introduce up to an additional 2% uncertainty. The choices in orbital fitting and evolutionary models can introduce significant uncertainties in measurements of physical properties of such systems.
- ID:
- ivo://CDS.VizieR/J/ApJ/887/109
- Title:
- EBs in Ruprecht 147. II. EPIC 219568666 LC & RVs
- Short Name:
- J/ApJ/887/109
- Date:
- 30 Nov 2021
- Publisher:
- CDS
- Description:
- We report our spectroscopic monitoring of the detached, grazing, and slightly eccentric 12 day double-lined eclipsing binary EPIC 219568666 in the old nearby open cluster Ruprecht 147. This is the second eclipsing system to be analyzed in this cluster, following our earlier study of EPIC 219394517. Our analysis of the radial velocities combined with the light curve from the K2 mission yields absolute masses and radii for EPIC 219568666 of M_1_=1.121+/-0.013M_{sun}_ and R_1_=1.1779+/-0.0070R_{sun}_ for the F8 primary and M_2_=0.7334+/-0.0050M_{sun}_ and R_2_=0.640+/-0.017R_{sun}_ for the faint secondary. Comparison with current stellar evolution models calculated for the known metallicity of the cluster points to a primary star that is oversized, as is often seen in active M dwarfs, but this seems rather unlikely for a star of its mass and with a low level of activity. Instead, we suspect a subtle bias in the radius ratio inferred from the photometry, despite our best efforts to avoid it, which may be related to the presence of spots on one or both stars. The radius sum for the binary, which bypasses this possible problem, indicates an age of 2.76+/-0.61Gyr, which is in good agreement with a similar estimate from the binary in our earlier study.
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/1879
- Title:
- EC Blue Object survey. -40{deg}>b>-50{deg}
- Short Name:
- J/MNRAS/453/1879
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results for Zone 3 of the Edinburgh-Cape (EC) Blue Object survey are presented. This zone covers that part of the South Galactic Cap between 40{deg} and 50{deg} from the Galactic plane and south of about -12.3{deg} of declination. EC Zone 3 contains 53 UK Schmidt Telescope fields covering about 1400 deg2 in which we find some 534 blue objects, including hot subdwarfs (~39 percent), white dwarfs (~21 percent), cataclysmic variables (~2 percent) and some star-like galaxies (~9 percent). A further 178 cooler stars observed in the survey, including low-metallicity F- and G-type stars, are also listed. Both low-dispersion spectroscopic classification and UBV photometry are presented for almost all of the hot objects and either spectroscopy or photometry (sometimes both) for the cooler ones.
- ID:
- ivo://CDS.VizieR/J/ApJ/796/60
- Title:
- ECDFS galaxies photometric redshifts & counterparts
- Short Name:
- J/ApJ/796/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometric redshifts and associated probability distributions for all detected sources in the Extended Chandra Deep Field South (ECDFS). This work makes use of the most up-to-date data from the Cosmic Assembly Near-IR Deep Legacy Survey (CANDELS) and the Taiwan ECDFS Near-Infrared Survey (TENIS) in addition to other data. We also revisit multi-wavelength counterparts for published X-ray sources from the 4Ms CDFS and 250ks ECDFS surveys, finding reliable counterparts for 1207 out of 1259 sources (~96%). Data used for photometric redshifts include intermediate-band photometry deblended using the TFIT method, which is used for the first time in this work. Photometric redshifts for X-ray source counterparts are based on a new library of active galactic nuclei/galaxy hybrid templates appropriate for the faint X-ray population in the CDFS. Photometric redshift accuracy for normal galaxies is 0.010 and for X-ray sources is 0.014 and outlier fractions are 4% and 5.2%, respectively. The results within the CANDELS coverage area are even better, as demonstrated both by spectroscopic comparison and by galaxy-pair statistics. Intermediate-band photometry, even if shallow, is valuable when combined with deep broadband photometry. For best accuracy, templates must include emission lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/642/L13
- Title:
- ECDFS MUSYC galaxies UBVRIzNB5000 photometry
- Short Name:
- J/ApJ/642/L13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We selected 40 candidate Ly{alpha}-emitting galaxies (LAEs) at z~3.1 with observed-frame equivalent widths greater than 150{AA} and inferred emission-line fluxes above 2.5x10^-17^ergs/cm^2^/s from deep narrowband and broadband MUSYC images of the Extended Chandra Deep Field South. Covering 992-arcmin^2^, this is the largest "blank field" surveyed for LAEs at z~3, allowing an improved estimate of the space density of this population of (3+/-1)x10^4^h/Mpc^3^. Spectroscopic follow-up of 23 candidates yielded 18 redshifts, all at z~3.1. Over 80% of the LAEs are dimmer in continuum magnitude than the typical Lyman break galaxy (LBG) spectroscopic limit of R=25.5 (AB), with a median continuum magnitude R~27 and very blue continuum colors, V-z~=0.
- ID:
- ivo://CDS.VizieR/J/AJ/159/189
- Title:
- Eclipse timings for 9 contact binaries
- Short Name:
- J/AJ/159/189
- Date:
- 08 Dec 2021
- Publisher:
- CDS
- Description:
- In this paper, we present the first light curve synthesis and orbital period change analysis of nine contact binaries around the short-period limit. It is found that all these systems are W-subtype contact binaries. One of them is a medium contact system while the others are shallow contact ones. Four of them manifest obvious O'Connell effect explained by a dark spot or hot spot on one of the component stars. Third light was detected in three systems. By investigating orbital period variations, we found that four of the targets display a secular period decrease while the others exhibit a long-term period increase. The secular period decrease is more likely caused by angular-momentum loss while the long-term period increase is due to mass transfer from the less massive component to the more massive one. Based on the statistic of 19 ultrashort-period contact binaries with known orbital period changes, we found that seven of them display long-term decrease (three of them also exhibit cyclic variations), ten of them manifest long-term increase while two of them only show cyclic variation, and that most of them are shallow contact binaries supporting the long timescale angular-momentum loss theory suggested by Stepien. For the three deep contact systems, we found that they are probably triple systems. The tertiary companion plays an essential role during their formation and evolution.
- ID:
- ivo://CDS.VizieR/J/A+A/506/501
- Title:
- Eclipsing binaries in CoRoT-LRc01 field
- Short Name:
- J/A+A/506/501
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present here the list of planetary transit candidates detected in the first long run observed by CoRoT: LRc01, towards the galactic center in the direction of Aquila, which lasted from May to October 2007. We analyzed 3719 (33%) sources in the chromatic bands and 7689 in the monochromatic band. Instrumental noise and the stellar variability were treated with several detrending tools, on which subsequently several transit search algorithms were applied. Forty two sources were classified as planetary transit candidates and up to now 26 cases have been solved. One planet (CoRoT-2b) and one brown-dwarf (CoRoT-3b) have been the subjects of detailed publications.
