- ID:
- ivo://CDS.VizieR/J/A+A/380/238
- Title:
- Long-period companions of multiple stars
- Short Name:
- J/A+A/380/238
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examined the statistics of an angle gamma between the radius vector of a visual companion of a multiple star and the vector of its apparent relative motion in the system. We found that for the wide physical subsystems of the 174 objects from the Multiple Star Catalogue (MSC, Cat. <J/A+AS/124/75>) gamma is bell-shaped. Table 1 presents the separation and position angle of visual outer companions of the sample multiples, and the relative motion (since discovery) and its direction - angle gamma with its error. Positions are taken for the first epoch mostly from Washington Double Star catalogue (WDS, Cat. <I/237>) and from Hipparcos (Cat. <I/239>) or Tycho (Cat. <I/239> and <I/259>) catalogues for the second epoch. Orbital motion in inner subsystems of multiple stars is taken into account in gamma when significant. Table 2 gives the cross-identification of objects and components in different catalogues.
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- ID:
- ivo://CDS.VizieR/J/ApJS/161/394
- Title:
- Low-luminosity companions to white dwarfs
- Short Name:
- J/ApJS/161/394
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents results of a near-infrared imaging survey for low-mass stellar and substellar companions to white dwarfs. A wide-field proper-motion survey of 261 white dwarfs was capable of directly detecting companions at orbital separations between 100 and 5000 AU with masses as low as 0.05M_{sun}_, while a deep near-field search of 86 white dwarfs was capable of directly detecting companions at separations between 50 and 1100AU with masses as low as 0.02M_{sun}_. Additionally, all white dwarf targets were examined for near-infrared excess emission, a technique capable of detecting companions at arbitrarily close separations down to masses of 0.05M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/AJ/133/394
- Title:
- Low-mass binary companions in M35
- Short Name:
- J/AJ/133/394
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Hubble Space Telescope Fine Guidance Sensors data on 23 stars in the intermediate-age cluster M35 having B-V<0.5 (~F7V) are analyzed to test whether binary periods, separations, and masses can be estimated by measuring periodic variations in the residuals of their internal proper motions. Of the 23 stars examined, 4 appear to possess a periodic signal. Unfortunately, these detections cannot be considered firm because the amplitudes of these waveforms are small (~1mas), the signal is only seen in one coordinate, and the derived periods are close to the duration of the data set. If the signals are real, they predict binary separations of >6AU, secondary masses between 0.3 and 0.6M_{sun}_, and mass ratios of about 0.2. This latter value is in agreement with capture models employing stars with circumstellar disks for the formation of binaries.
- ID:
- ivo://CDS.VizieR/J/AJ/141/52
- Title:
- Low-mass visual companions to nearby G-dwarfs
- Short Name:
- J/AJ/141/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A complete census of wide visual companions to nearby G-dwarf stars can be achieved by selecting candidates from the Two Micron All Sky Survey (2MASS) Point-Source Catalog and checking their status by second-epoch imaging. Such data are obtained for 124 candidates with separations up to 20", 47 of which are shown to be new physical low-mass stellar companions. A list of visual binaries with G-dwarf primaries is produced by combining newly found companions with historical data.
- ID:
- ivo://CDS.VizieR/J/MNRAS/471/4218
- Title:
- 4 low-mass white-dwarf candidates velocities
- Short Name:
- J/MNRAS/471/4218
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results from a Gemini snapshot radial-velocity survey of 44 low-mass white-dwarf candidates selected from the Sloan Digital Sky Survey (SDSS) spectroscopy. To find sub-hour orbital period binary systems, our time-series spectroscopy had cadences of 2-8min over a period of 20-30min. Through follow-up observations at Gemini and the MMT, we identify four double-degenerate binary systems with periods ranging from 53min to 7h. The shortest period system, SDSS J123549.88+154319.3, was recently identified as a sub-hour period detached binary by Breedt and collaborators. Here, we refine the orbital and physical parameters of this system. High-speed and time-domain survey photometry observations do not reveal eclipses or other photometric effects in any of our targets. We compare the period distribution of these four systems with the orbital period distribution of known double white dwarfs; the median period decreases from 0.64 to 0.24d for M=0.3-0.5M_{sun}_ to M<0.3M_{sun}_ white dwarfs. However, we do not find a statistically significant correlation between the orbital period and white-dwarf mass.
- ID:
- ivo://CDS.VizieR/J/A+A/522/A65
- Title:
- Lunar occultations at the ESO VLT
- Short Name:
- J/A+A/522/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Lunar occultations (LO) are a very efficient and powerful technique that achieves the best combination of high angular resolution and sensitivity possible today at near-infrared wavelengths. Given that the events are fixed in time, that the sources are occulted randomly, and that the telescope use is minimal, the technique is very well suited for service mode observations. We have established a program of routine LO observations at the VLT observatory, especially designed to take advantage of short breaks available in-between other programs. We have used the ISAAC instrument in burst mode, capable of producing continuous read-outs at millisecond rates on a suitable subwindow. Given the random nature of the source selection, our aim has been primarily the investigation of a large number of stellar sources at the highest angular resolution in order to detect new binaries. Serendipitous results such as resolved sources and detection of circumstellar components were also anticipated.
- ID:
- ivo://CDS.VizieR/J/other/JAVSO/48.201
- Title:
- Maintaining the Ephemeris of 20 CoRoT planets
- Short Name:
- J/other/JAVSO/48
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present 33 transit minimum times of 20 transiting planets discovered by the CoRoT space mission, which have been obtained from ground-based observations since the mission's end in 2012, with the objective to maintain the ephemeris of these planets and to identify potential transit time variations. Twelve of the observed planets are in the CoRoT fields near the galactic center and the remaining eight planets are in the fields near the anticenter. We detect indications for significant transit timing variations in the cases of CoRoT 3b, 11b, 13b, 27b. For two more planets (CoRoT 18b and 20b) we conclude that timing offsets in early follow-up observations led to ephemeris in discovery publications that are inconsistent with timings from follow-up observations in later epochs. In the case of CoRoT-20b, this might be due to the influence from a further non-transiting planet. We also note that a significant majority (23 of 33) of our reported minimum times have negative O-C values, albeit most of them are within the expected uncertainty of the ephemeris.
- ID:
- ivo://CDS.VizieR/J/AJ/131/1015
- Title:
- MAP observations of the position of Procyon
- Short Name:
- J/AJ/131/1015
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the analysis of observations of Procyon obtained with the Multichannel Astrometric Photometer during the years 1986-2004. While the results significantly increase the precision of the estimated characteristics of the components of the system, they are generally in good agreement with the most recent studies.
- ID:
- ivo://CDS.VizieR/J/A+A/612/A57
- Title:
- MASCARA-2 b (HD185603) light curves and spectra
- Short Name:
- J/A+A/612/A57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present MASCARA-2 b, a hot Jupiter transiting the m_V_=7.6 A2 star HD 185603. Since early 2015, MASCARA has taken more than 1.6 million flux measurements of the star, corresponding to a total of almost 3000 hours of observations, revealing a periodic dimming in the flux with a depth of 1.3%. Photometric follow-up observations were performed with the NITES and IAC80 telescopes and spectroscopic measurements were obtained with the Hertzsprung SONG telescope. We find MASCARA-2 b orbits HD 185603 with a period of 3.474119^+0.000005^_-0.000006_ days at a distance of 0.057+/-0.006AU, has a radius of 1.83+/-0.07R_J_ and place a 99 % upper limit on the mass of <17M_J_. HD 185603 is a rapidly rotating early-type star with an effective temperature of 8980^+90^_-130_K and a mass and radius of 1.89^+0.06^_-0.05_M_sun_, 1.60+/-0.06R_sun_, respectively. Contrary to most other hot Jupiters transiting early-type stars, the projected planet orbital axis and stellar spin axis are found to be aligned with {lambda}=0.6+/-4{deg}. The brightness of the host star and the high equilibrium temperature, 2260+/-50K, of MASCARA-2 b make it a suitable target for atmospheric studies from the ground and space. Of particular interest is the detection of TiO, which has recently been detected in the similarly hot planets WASP-33 b and WASP-19 b.
- ID:
- ivo://CDS.VizieR/J/A+A/624/A78
- Title:
- Masses and ages of 1059 HARPS-GTO stars
- Short Name:
- J/A+A/624/A78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The purpose of this work is to evaluate how several elements produced by different nucleosynthesis processes behave with stellar age and provide empirical relations to derive stellar ages from chemical abundances. We derived different sets of ages using Padova and Yonsei-Yale isochrones and Hipparcos and Gaia parallaxes for a sample of more than 1000 FGK dwarf stars for which he have high-resolution R~115000 and high-quality spectra from the HARPS-GTO program. We analyzed the temporal evolution of different abundance ratios to find the best chemical clocks. We applied multivariable linear regressions to our sample of stars with a small uncertainty on age to obtain empirical relations of age as a function of stellar parameters and different chemical clocks. We find that [alpha/Fe] ratio (average of Mg, Si, and Ti), [O/Fe] and [Zn/Fe] are good age proxies with a lower dispersion than the age-metallicity dispersion. Several abundance ratios present a significant correlation with age for chemically separated thin disk stars (i.e., low-alpha) but in the case of the chemically defined thick disk stars (i.e., high-alpha) only the elements Mg, Si, Ca, and TiII show a clear correlation with age. We find that the thick disk stars are more enriched in light-s elements than thin disk stars of similar age. The maximum enrichment of s-process elements in the thin disk occurs in the youngest stars which in turn have solar metallicity. The slopes of the [X/Fe]-age relations are quite constant for O, Mg, Si, Ti, Zn, Sr, and Eu regardless of the metallicity. However, this is not the case for Al, Ca, Cu and most of the s-process elements, which display very different trends depending on the metallicity. This demonstrates the limitations of using simple linear relations based on certain abundance ratios to obtain ages for stars of different metallicities. Finally, we show that by using 3D relations with a chemical clock and two stellar parameters (either Teff, [Fe/H] or stellar mass) we can explain up to 89% of age variance in a star. A similar result is obtained when using 2D relations with a chemical clock and one stellar parameter, explaining up to a 87% of the variance. The complete understanding of how the chemical elements were produced and evolved in the Galaxy requires the knowledge of stellar ages and precise chemical abundances. We show how the temporal evolution of some chemical species change with metallicity, with remarkable variations at super-solar metallicities, which will help to better constrain the yields of different nucleosynthesis processes along the history of the Galaxy.