- ID:
- ivo://CDS.VizieR/J/AJ/160/49
- Title:
- LOAO BV-bands photometry and BOES RVs of WASP 0131+28
- Short Name:
- J/AJ/160/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the first BV light curves and high-resolution spectra of the post-mass transfer binary star WASP0131+28 to study the absolute properties of extremely low-mass white dwarfs. From the observed spectra, the double-lined radial velocities were derived, and the effective temperature and rotational velocity of the brighter, more massive primary were found to be Teff_1_=10000{+/-]200K and v_1_sin_i_=55{+/-}10km/s, respectively. The combined analysis of the Transiting Exoplanet Survey Satellite (TESS) archive data and ours yielded the accurate fundamental parameters of the program target. The masses were derived to about 1.0% accuracy and the radii to 0.6%, or better. The secondary component's parameters of M_2_=0.200{+/-}0.002M_{sun}_, R_2_=0.528{+/-}0.003R_{sun}_, Teff_2_=11186{+/-}235K, and L_2_=3.9{+/-}0.3L_{sun}_ are in excellent agreement with the evolutionary sequence for a helium-core white dwarf of mass 0.203M_{sun}, and indicates that this star is halfway through the constant luminosity phase. The results presented in this article demonstrate that WASP0131+28 is an EL CVn eclipsing binary in a thin disk, which is formed from the stable Roche-lobe overflow channel and composed of a main-sequence dwarf with a spectral type A0 and a pre-He white dwarf.
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- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/764/131
- Title:
- Long-term monitoring of Barnard's star velocity
- Short Name:
- J/ApJ/764/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 248 precise Doppler measurements of Barnard's Star (Gl 699), the second nearest star system to Earth, obtained from Lick and Keck Observatories during the 25 years between 1987 and 2012. The early precision was 20m/s but was 2m/s during the last 8 years, constituting the most extensive and sensitive search for Doppler signatures of planets around this stellar neighbor. We carefully analyze the 136 Keck radial velocities spanning 8 years by first applying a periodogram analysis to search for nearly circular orbits. We find no significant periodic Doppler signals with amplitudes above ~2m/s, setting firm upper limits on the minimum mass (Msini) of any planets with orbital periods from 0.1 to 1000 days. Using a Monte Carlo analysis for circular orbits, we determine that planetary companions to Barnard's Star with masses above 2M_{oplus}_ and periods below 10 days would have been detected. Planets with periods up to 2yr and masses above 10M_{oplus}_ (0.03M_Jup_) are also ruled out. A similar analysis allowing for eccentric orbits yields comparable mass limits. The habitable zone of Barnard's Star appears to be devoid of roughly Earth-mass planets or larger, save for face-on orbits. Previous claims of planets around the star by van de Kamp are strongly refuted. The radial velocity of Barnard's Star increases with time at 4.515+/-0.002m/s/yr, consistent with the predicted geometrical effect, secular acceleration, that exchanges transverse for radial components of velocity.
- 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/636/A58
- Title:
- L 168-9 radial velocity curve
- Short Name:
- J/A+A/636/A58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of a transiting super-Earth-sized planet (R=1.39+/-0.09R_{Earth}_) in a 1.4-day orbit around L 168-9 (TOI-134), a bright M1V dwarf (V=11, K=7.1) located at 25.15+/-0.02pc. The host star was observed in the first sector of the Transiting Exoplanet Survey Satellite (TESS) mission. For confirmation and planet mass measurement purposes, this was followed up with ground-based photometry, seeing-limited and high-resolution imaging, and precise radial velocity (PRV) observations using the HARPS and Magellan/PFS spectrographs. By combining the TESS data and PRV observations, we find the mass of L 168-9 b to be 4.60+/-0.56M_{Earth}_ and thus the bulk density to be 1.74^+0.44^_-0.33_ times higher than that of the Earth. The orbital eccentricity is smaller than 0.21 (95% confidence). This planet is a level one candidate for the TESS mission's scientific objective of measuring the masses of 50 small planets, and it is one of the most observationally accessible terrestrial planets for future atmospheric characterization.
- ID:
- ivo://CDS.VizieR/J/A+A/653/A41
- Title:
- L 98-59 (TOI-175) ESPRESSO observations
- Short Name:
- J/A+A/653/A41
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- In recent years, the advent of a new generation of radial velocity instruments has allowed us to detect lower and lower mass planets, breaking the one Earth-mass barrier. Here we report a new milestone in this context, by announcing the detection of the lightest planet measured so far using radial velocities: L 98-59 b, a rocky planet with half the mass of Venus which is part of a system composed of three known transiting terrestrial planets (planets b to d). We announce the discovery of a fourth non-transiting planet with a minimum mass of 3.06_-0.37_^+0.33^M_{Earth)_ and an orbital period of 12.796_-0.019_^+0.020^ days and report hints for the presence of a fifth non-transiting terrestrial planet. If confirmed, with a minimum mass of 2.46_-0.82_^+0.66^M_{Earth}_ and an orbital period 23.15_-0.17_^+0.60^ days, this planet would sit in the middle of the habitable zone of the L 98-59 system. L 98-59 is a bright M-dwarf located 10.6pc away. Positioned at the border of the continuous viewing zone of the James Webb space telescope, this system is destined to become a corner stone for comparative exoplanetology of terrestrial planets. The three transiting planets have transmission spectrum metrics ranging from 49 to 255 which undoubtedly make them prime targets for atmospheric characterization with the James Webb space telescope, the Hubble space telescope, Ariel or ground-based facilities like NIRPS or ESPRESSO. With equilibrium temperature ranging from 416 to 627K, they offer a unique opportunity to study the diversity of warm terrestrial planets without the unknowns associated with different host stars. L 98-59 b and c have densities of 3.6_-1.5_^+1.4^ and 4.57_-0.85_^+0.77^g/cm^3^ respectively and have very similar bulk compositions with a small iron core, representing only 12 to 14% of the total mass, and a small amount of water. However, with a density of 2.95_-0.51_^+0.79^g/cm^3^ and despite a similar core mass fraction, up to 30% of L 98-59 d's mass could be made of water.
- ID:
- ivo://CDS.VizieR/J/A+A/629/A111
- Title:
- L 98-59 (TOI 175) HARPS observations
- Short Name:
- J/A+A/629/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- L 98-59 (TIC 307210830, TOI-175) is a nearby M3 dwarf around which TESS revealed three small transiting planets (0.80, 1.35, 1.57 Earth radii) in a compact configuration with orbital periods shorter than 7.5 days. Here we aim to measure the masses of the known transiting planets in this system using precise radial velocity (RV) measurements taken with the HARPS spectrograph. We considered both trained and untrained Gaussian process regression models of stellar activity, which are modeled simultaneously with the planetary signals. Our RV analysis was then supplemented with dynamical simulations to provide strong constraints on the planets' orbital eccentricities by requiring long-term stability. We measure the planet masses of the two outermost planets to be 2.42+/-0.35 and 2.31+/-0.46 Earth masses, which confirms the bulk terrestrial composition of the former and eludes to a significant radius fraction in an extended gaseous envelope for the latter. We are able to place an upper limit on the mass of the smallest, innermost planet of <1.01 Earth masses with 95% confidence. Our RV plus dynamical stability analysis places strong constraints on the orbital eccentricities and reveals that each planet's orbit likely has e<0.1. L 98-59 is likely a compact system of two rocky planets plus a third outer planet with a lower bulk density possibly indicative of the planet having retained a modest atmosphere. The system offers a unique laboratory for studies of planet formation, dynamical stability, and comparative atmospheric planetology as the two outer planets are attractive targets for atmospheric characterization through transmission spectroscopy. Continued RV monitoring will help refine the characterization of the innermost planet and potentially reveal additional planets in the system at wider separations.
