- ID:
- ivo://CDS.VizieR/J/A+A/464/581
- Title:
- Sco OB2 intermediate-mass stars
- Short Name:
- J/A+A/464/581
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present JHK observations of 22 intermediate-mass stars in Sco OB2, obtained with NACO. This survey was performed to determine the status of (sub)stellar candidate companions of Sco OB2 member stars of spectral type A and late-B. The distinction between companions and background stars is made on the basis of a comparison to isochrones and additional statistical arguments. We include in our sample a subset of 9 targets with multi-color ADONIS observations from Kouwenhoven et al. (2005, Cat. <J/A+A/430/137>). We reanalyse the total sample (i.e. NACO and ADONIS) and conclude that of the 176 secondaries, 25 are physical companions, 55 are candidate companions, and 96 are background stars. Although we are sensitive (and complete) to brown dwarf companions as faint as K=14mag in the semi-major axis range 130-520AU, we detect only one, corresponding to a brown dwarf companion fraction of 0.5% (M>30M_Jupiter_). However, the number of brown dwarfs is consistent with an extrapolation of the (stellar) companion mass distribution into the brown dwarf regime. This indicates that the physical mechanism for the formation of brown dwarf companions around intermediate mass stars is similar to that of stellar companions, and that the embryo ejection mechanism does not need to be invoked in order to explain the small number of brown dwarf companions among intermediate mass stars in Sco OB2.
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Search Results
1012. SDSS J162520.29+120308.7
- ID:
- ivo://CDS.VizieR/J/A+A/532/A64
- Title:
- SDSS J162520.29+120308.7
- Short Name:
- J/A+A/532/A64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/MNRAS/413/1121
- Title:
- SDSS post-common envelope binaries. X
- Short Name:
- J/MNRAS/413/1121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first white dwarf mass distributions of a large and homogeneous sample of post-common envelope binaries (PCEBs) and wide white dwarf main-sequence (WDMS) binaries directly obtained from observations. Both distributions are statistically independent, with PCEBs showing a clear concentration of systems towards the low-mass end of the distribution and the white dwarf mass distribution of wide WDMS binaries being similar to that of single white dwarfs. Our results provide evidence that the majority of low-mass (Mwd<~0.5M_{sun}_) white dwarfs are formed in close binaries.
- ID:
- ivo://CDS.VizieR/J/MNRAS/382/1377
- Title:
- SDSS WD main-sequence binaries
- Short Name:
- J/MNRAS/382/1377
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed analysis of 101 white dwarf main-sequence binaries (WDMS) from the Sloan Digital Sky Survey (SDSS) for which multiple SDSS spectra are available.
- ID:
- ivo://CDS.VizieR/J/MNRAS/402/620
- Title:
- SDSS WD main-sequence binaries
- Short Name:
- J/MNRAS/402/620
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of 1602 white-dwarf-main-sequence (WDMS) binaries from the spectroscopic Sloan Digital Sky Survey Data Release 6 (SDSS DR6). Among these, we identify 440 as new WDMS binaries. We select WDMS binary candidates by template fitting all 1.27 million DR6 spectra, using combined constraints in both chi^2^ and signal-to-noise ratio. In addition, we use Galaxy Evolution Explorer (GALEX) and UKIRT Infrared Sky Survey (UKIDSS) magnitudes to search for objects in which one of the two components dominates the SDSS spectrum. We use a decomposition/fitting technique to measure the effective temperatures, surface gravities, masses and distances to the white dwarfs, as well as the spectral types and distances to the companions in our catalogue
- ID:
- ivo://CDS.VizieR/J/A+A/536/A43
- Title:
- SDSS WD main-sequence binaries. XII.
- Short Name:
- J/A+A/536/A43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The complexity of the common-envelope phase and of magnetic stellar wind braking currently limits our understanding of close binary evolution. Because of their intrinsically simple structure, observational population studies of white dwarf plus main sequence (WDMS) binaries can potentially test theoretical models and constrain their parameters. The Sloan Digital Sky Survey (SDSS) has provided a large and homogeneously selected sample of WDMS binaries, which we characterise in terms of orbital and stellar parameters. We have obtained radial velocity information for 385 WDMS binaries from follow-up spectroscopy and for an additional 861 systems from the SDSS subspectra. Radial velocity variations identify 191 of these WDMS binaries as post common-envelope binaries (PCEBs). Orbital periods of 58 PCEBs were subsequently measured, predominantly from time-resolved spectroscopy, bringing the total number of SDSS PCEBs with orbital parameters to 79. Observational biases inherent to this PCEB sample were evaluated through extensive Monte Carlo simulations. We find that 21-24% of all SDSS WDMS binaries have undergone common-envelope evolution, which is in good agreement with published binary population models and high-resolution HST imaging of WDMS binaries unresolved from the ground. The bias-corrected orbital period distribution of PCEBs ranges from 1.9h to 4.3d and approximately follows a normal distribution in log(Porb), peaking at ~10.3h. There is no observational evidence for a significant population of PCEBs with periods in the range of days to weeks. The large and homogeneous sample of SDSS WDMS binaries provides the means to test fundamental predictions of binary population models, hence to observationally constrain the evolution of all close compact binaries.
- ID:
- ivo://CDS.VizieR/J/ApJ/815/63
- Title:
- SDSS wide double white dwarfs spectroscopy
- Short Name:
- J/ApJ/815/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observational constraints on the initial-final mass relation (IFMR) using wide double white dwarfs (DWDs). We identify 65 new candidate wide DWDs within the Sloan Digital Sky Survey, bringing the number of candidate wide DWDs to 142. We then engage in a spectroscopic follow-up campaign and collect existing spectra for these objects; using these spectra, we derive masses and cooling ages for 54 hydrogen (DA) WDs in DWDs. We also identify one new DA/DB pair, four candidate DA/DC pairs, four candidate DA/DAH pairs, and one new candidate triple degenerate system. Because wide DWDs are co-eval and evolve independently, the difference in the pre-WD lifetimes should equal the difference in the WD cooling ages. We use this to develop a Bayesian hierarchical framework and construct a likelihood function to determine the probability that any particular IFMR fits a sample of wide DWDs. We then define a parametric model for the IFMR and find the best parameters indicated by our sample of DWDs. We place robust constraints on the IFMR for initial masses of 2-4M_{sun}_. The WD masses produced by our model for stars within this mass range differ from those predicted by semi-empirical fits to open cluster WDs. Within this mass range, where there are few constraining open cluster WDs and disagreements in the cluster ages, wide DWDs may provide more reliable constraints on the IFMR. Expanding this method to the many wide DWDs expected to be discovered by Gaia may transform our understanding of the IFMR.
- ID:
- ivo://CDS.VizieR/J/ApJ/736/89
- Title:
- Search for companions around nearby massive stars
- Short Name:
- J/ApJ/736/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this study, we present high-contrast imaging of 18 nearby massive stars of which 15 are in the B2-A0 spectral-type range and provide excellent sensitivity to wide companions. By comparing our sensitivities to model predictions of disk instability based on physical criteria for fragmentation and cooling, and using Monte Carlo simulations for orbital distributions, we find that ~85% of such companions should have been detected in our images on average. Given this high degree of completeness, stringent statistical limits can be set from the null-detection result, even with the limited sample size. We find that <30% of massive stars form and retain disk instability planets, brown dwarfs, and very low mass stars of <100M_jup_ within 300AU, at 99% confidence. These results, combined with previous findings in the literature, lead to the conclusion that core accretion is likely the dominant mode of planet formation.
- ID:
- ivo://CDS.VizieR/J/ApJ/700/1647
- Title:
- Search for planetary companions with Spitzer/IRAC
- Short Name:
- J/ApJ/700/1647
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Fomalhaut and {epsilon} Eridani are two young, nearby stars that possess extended debris disks whose structures suggest the presence of perturbing planetary objects. With its high sensitivity and stable point-spread function, Spitzer/Infrared Array Camera (IRAC) is uniquely capable of detecting cool, Jupiter-like planetary companions whose peak emission is predicted to occur near 4.5um. We report on deep IRAC imaging of these two stars, taken at 3.6 and 4.5um using subarray mode and in all four channels in wider-field full array mode. Observations acquired at two different telescope roll angles allowed faint surrounding objects to be separated from the stellar diffraction pattern. No companion candidates were detected at the reported position of Fomalhaut b with 3{sigma} model-dependent mass upper limits of 3M_J_ (for an age of 200Myr). Around {epsilon} Eridani, we instead set a limit of 4 and <~1M_J_ (1Gyr model age) at the inner and outer edge of the submillimeter debris ring, respectively. These results are consistent with non-detections in recent near-infrared imaging searches, and set the strongest limits to date on the presence of planets outside {epsilon} Eridani submillimeter ring.
- ID:
- ivo://CDS.VizieR/J/AcA/70/181
- Title:
- Search for Planets in Hot Jupiter Systems
- Short Name:
- J/AcA/70/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Origins of giant planets on tight orbits, so called hot Jupiters, are a long-lasting question in the planetary formation and evolution theory. The answer seems to be hidden in architectures of those systems that remain only partially understood. Using multi-sector time-series photometry from the Transiting Exoplanet Survey Satellite, we searched for additional planets in the KELT-18, KELT-23, KELT-24, Qatar-8, WASP-62, WASP-100, WASP-119, and WASP-126 planetary systems using both the transit technique and transit timing method. Our homogeneous analysis has eliminated the presence of transiting companions down to the terrestrial-size regime in the KELT-23 and WASP-62 systems, and down to mini-Neptunes or Neptunes in the remaining ones. Transit timing analysis has revealed no sign of either long-term trends or periodic perturbations for all the studied hot Jupiters, including the WASP-126 b for which deviations from a Keplerian model were claimed in the literature. The loneliness of the planets of the sample speaks in favor of the high-eccentricity migration mechanism that probably brought them to their tight orbits observed nowadays. As a by-product of our study, the transit light curve parameters were redetermined with a substantial improvement of the precision for six systems. For KELT-24 b, a joint analysis allowed us to place a tighter constraint on its orbital eccentricity.
