- ID:
- ivo://CDS.VizieR/J/A+A/529/A102
- Title:
- MOA-2007-BLG-387Lb light curve I band
- Short Name:
- J/A+A/529/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a planet with a high planet-to-star mass ratio in the microlensing event MOA-2009-BLG-387, which exhibited pronounced deviations over a 12-day interval, one of the longest for any planetary event. The host is an M dwarf, with a mass in the range 0.07M_{sun}_<M_host_<0.49M_{sum}_ at 90% confidence. The planet-star mass ratio q=0.0132+/-0.003 has been measured extremely well, so at the best-estimated host mass, the planet mass is m_p_=2.6 Jupiter masses for the median host mass, M=0.19M_{sun}_.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/153/93
- Title:
- MOST photometry of Proxima
- Short Name:
- J/AJ/153/93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The analysis of Proxima Centauri's radial velocities recently led Anglada-Escude et al. to claim the presence of a low-mass planet orbiting the Sun's nearest star once every 11.2 days. Although the a priori probability that Proxima b transits its parent star is just 1.5%, the potential impact of such a discovery would be considerable. Independent of recent radial velocity efforts, we observed Proxima Centauri for 12.5 days in 2014 and 31 days in 2015 with the Microwave and Oscillations of Stars space telescope. We report here that we cannot make a compelling case that Proxima b transits in our precise photometric time series. Imposing an informative prior on the period and phase, we do detect a candidate signal with the expected depth. However, perturbing the phase prior across 100 evenly spaced intervals reveals one strong false positive and one weaker instance. We estimate a false-positive rate of at least a few percent and a much higher false-negative rate of 20%-40%, likely caused by the very high flare rate of Proxima Centauri. Comparing our candidate signal to HATSouth ground-based photometry reveals that the signal is somewhat, but not conclusively, disfavored (1{sigma}-2{sigma}), leading us to argue that the signal is most likely spurious. We expect that infrared photometric follow-up could more conclusively test the existence of this candidate signal, owing to the suppression of flare activity and the impressive infrared brightness of the parent star.
- ID:
- ivo://CDS.VizieR/J/ApJ/900/154
- Title:
- Mount Wilson S-Index of 94 Aqr A and 94 Aqr B
- Short Name:
- J/ApJ/900/154
- Date:
- 02 Feb 2022 13:08:40
- Publisher:
- CDS
- Description:
- Most previous efforts to calibrate how rotation and magnetic activity depend on stellar age and mass have relied on observations of clusters, where isochrones from stellar evolution models are used to determine the properties of the ensemble. Asteroseismology employs similar models to measure the properties of an individual star by matching its normal modes of oscillation, yielding the stellar age and mass with high precision. We use 27 days of photometry from the Transiting Exoplanet Survey Satellite to characterize solar-like oscillations in the G8 subgiant of the 94 Aqr triple system. The resulting stellar properties, when combined with a reanalysis of 35yr of activity measurements from the Mount Wilson HK project, allow us to probe the evolution of rotation and magnetic activity in the system. The asteroseismic age of the subgiant agrees with a stellar isochrone fit, but the rotation period is much shorter than expected from standard models of angular momentum evolution. We conclude that weakened magnetic braking may be needed to reproduce the stellar properties, and that evolved subgiants in the hydrogen shell-burning phase can reinvigorate large-scale dynamo action and briefly sustain magnetic activity cycles before ascending the red giant branch.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A85
- Title:
- M67 stars radial velocities
- Short Name:
- J/A+A/603/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a seven-year-long radial velocity survey of a sample of 88 main-sequence and evolved stars to reveal signatures of Jupiter-mass planets in the solar-age and solar-metallicity open cluster M67. We analysed precise radial velocity (RV) measurements obtained with five different instruments. We conducted Monte Carlo simulations to estimate the occurrence rate of giant planets in our radial velocity survey. All the planets previously announced in this RV campaign with their properties are summarised: 3 hot Jupiters around the main-sequence stars YBP1194, YBP1514, and YBP401, and 1 giant planet around the evolved star S364. Two additional planet candidates around the stars YBP778 and S978 are also analysed. We discuss stars that exhibit large RV variability or trends individually. We find an occurrence of giant planets of ~18.0% in a selected period-mass range. This frequency is slightly higher but consistent within the errors with the estimate for the field stars, leading to the general conclusion that open cluster and field statistics agree. However, we find that the rate of hot Jupiters in the cluster (~5.7%) is substantially higher than in the field.
- ID:
- ivo://CDS.VizieR/J/MNRAS/459/1393
- Title:
- Multi-band light curve of WASP-36
- Short Name:
- J/MNRAS/459/1393
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present broad-band photometry of five transits in the planetary system WASP-36, totaling 17 high-precision light curves. Four of the transits were simultaneously observed in four passbands (g', r', i', z'), using the telescope-defocussing technique, and achieving scatters of less than 1 mmag per observation. We used these data to improve the measured orbital and physical properties of the system, and obtain an optical transmission spectrum of the planet. We measured a decreasing radius from bluer to redder passbands with a confidence level of more than 5 sigma. The radius variation is roughly 11 pressure scale heights between the g' and the z' bands. This is too strong to be Rayleigh scattering in the planetary atmosphere, and implies the presence of a species which absorbs strongly at bluer wavelengths.
- ID:
- ivo://CDS.VizieR/J/AJ/159/139
- Title:
- Multiple M dwarf stars with Robo-AO and Gaia DR2
- Short Name:
- J/AJ/159/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze observations from Autonomous laser-adaptive-optics for few-meter-class telescopes (Robo-AO)'s field M dwarf survey taken on the 2.1m Kitt Peak telescope and perform a multiplicity comparison with Gaia DR2. Through its laser-guided, automated system, the Robo-AO instrument has yielded the largest adaptive optics M dwarf multiplicity survey to date. After developing an interface to visually identify and locate stellar companions, we selected 11 low-significance Robo-AO detections for follow-up on the Keck II telescope using NIRC2. In the Robo-AO survey we find 553 candidate companions within 4" around 534 stars out of 5566 unique targets, most of which are new discoveries. Using a position cross-match with DR2 on all targets, we assess the binary recoverability of Gaia DR2 and compare the properties of multiples resolved by both Robo-AO and Gaia. The catalog of nearby M dwarf systems and their basic properties presented here can assist other surveys which observe these stars, such as the NASA Transiting Exoplanet Survey Satellite (TESS) mission.
- ID:
- ivo://CDS.VizieR/J/A+AS/124/75
- Title:
- Multiple star catalogue (MSC)
- Short Name:
- J/A+AS/124/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Data on 728 stellar systems of multiplicity 3 to 7 are given. All systems are physical and, with little exception, hierarchical. They are represented as several "elementary binaries". For each binary the orbital period and separation are given, as well as component magnitudes, spectral types and estimated masses. Orbital elements are also given when available. The present (1999) version of the catalogue is updated as compared to the original 1997 publication, with some changes in the format.
- ID:
- ivo://CDS.VizieR/J/ApJ/813/83
- Title:
- Multiple star formation in Ophiuchus
- Short Name:
- J/ApJ/813/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conduct a multiplicity survey of members of the {rho} Ophiuchus cloud complex with high-resolution imaging to characterize the multiple-star population of this nearby star-forming region and investigate the relation between stellar multiplicity and star and planet formation. Our aperture masking survey reveals the presence of five new stellar companions beyond the reach of previous studies, but does not result in the detection of any new substellar companions. We find that 43+/-6% of the 114 stars in our survey have stellar-mass companions between 1.3 and 780 AU, while 7_-5_^+8^% host brown dwarf companions in the same interval. By combining this information with knowledge of disk-hosting stars, we show that the presence of a close binary companion (separation <40AU) significantly influences the lifetime of protoplanetary disks, a phenomenon previously seen in older star-forming regions. At the ~1-2Myr age of our Ophiuchus members ~2/3 of close binary systems have lost their disks, compared to only ~30% of single stars and wide binaries. This has a significant impact on the formation of giant planets, which are expected to require much longer than 1 Myr to form via core accretion and thus planets formed via this pathway should be rare in close binary systems.
- ID:
- ivo://CDS.VizieR/J/ApJ/731/8
- Title:
- Multiple star formation in Taurus-Auriga
- Short Name:
- J/ApJ/731/8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a high-resolution imaging study of the Taurus-Auriga star-forming region in order to characterize the primordial outcome of multiple star formation and the extent of the brown dwarf desert. Our survey identified 16 new binary companions to primary stars with masses of 0.25-2.5M_{sun}_, raising the total number of binary pairs (including components of high-order multiples) with separations of 3-5000AU to 90. We find that ~2/3-3/4 of all Taurus members are multiple systems of two or more stars, while the other ~1/4-1/3 appear to have formed as single stars; the distribution of high-order multiplicity suggests that fragmentation into a wide binary has no impact on the subsequent probability that either component will fragment again. The separation distribution for solar-type stars (0.7-2.5M_{sun}_) is nearly log-flat over separations of 3-5000AU, but lower-mass stars (0.25-0.7M_{sun}_) show a paucity of binary companions with separations of >~200AU. Across this full mass range, companion masses are well described with a linear-flat function; all system mass ratios (q=M_B_/M_A_) are equally probable, apparently including substellar companions. Our results are broadly consistent with the two expected modes of binary formation (free-fall fragmentation on large scales and disk fragmentation on small scales), but the distributions provide some clues as to the epochs at which the companions are likely to form.
- ID:
- ivo://CDS.VizieR/J/AJ/155/160
- Title:
- Multiple systems:relative positions and residuals
- Short Name:
- J/AJ/155/160
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper draws attention to the class of resolved triple stars with moderate ratios of inner and outer periods (possibly in a mean motion resonance) and nearly circular, mutually aligned orbits. Moreover, stars in the inner pair are twins with almost identical masses, while the mass sum of the inner pair is comparable to the mass of the outer component. Such systems could be formed either sequentially (inside-out) by disk fragmentation with subsequent accretion and migration, or by a cascade hierarchical fragmentation of a rotating cloud. Orbits of the outer and inner subsystems are computed or updated in four such hierarchies: LHS 1070 (GJ 2005, periods 77.6 and 17.25 years), HIP 9497 (80 and 14.4 years), HIP 25240 (1200 and 47.0 years), and HIP 78842 (131 and 10.5 years).
