scholarly journals Stellar and substellar companions of nearby stars from Gaia DR2

2019 ◽  
Vol 623 ◽  
pp. A72 ◽  
Author(s):  
Pierre Kervella ◽  
Frédéric Arenou ◽  
François Mignard ◽  
Frédéric Thévenin
Keyword(s):  
Proper Motion ◽  
Motion Vector ◽  
Tangential Velocity ◽  
Long Period ◽  
Nearby Stars ◽  
Low Mass ◽  
Substellar Companions ◽  
Orbital Periods ◽  
The Masses

Context. The census of stellar and substellar companions of nearby stars is largely incomplete, in particular toward the low-mass brown dwarf and long-period exoplanets. It is, however, fundamentally important in the understanding of the stellar and planetary formation and evolution mechanisms. Nearby stars are particularly favorable targets for high precision astrometry. Aims. We aim to characterize the presence of physical companions of stellar and substellar mass in orbit around nearby stars. Methods. Orbiting secondary bodies influence the proper motion of their parent star through their gravitational reflex motion. Using the HIPPARCOS and Gaia’s second data release (GDR2) catalogs, we determined the long-term proper motion of the stars common to these two catalogs. We then searched for a proper motion anomaly (PMa) between the long-term proper motion vector and the GDR2 (or HIPPARCOS) measurements, indicative of the presence of a perturbing secondary object. We focussed our analysis on the 6741 nearby stars located within 50 pc, and we also present a catalog of the PMa for ≳99% of the HIPPARCOS catalog (≈117 000 stars). Results. 30% of the stars studied present a PMa greater than 3σ. The PMa allows us to detect orbiting companions, or set stringent limits on their presence. We present a few illustrations of the PMa analysis to interesting targets. We set upper limits of 0.1−0.3 MJ to potential planets orbiting Proxima between 1 and 10 au (Porb = 3 to 100 years). We confirm that Proxima is gravitationally bound to α Cen. We recover the masses of the known companions of ϵ Eri, ϵ Ind, Ross 614 and β Pic. We also detect the signature of a possible planet of a few Jovian masses orbiting τ Ceti. Conclusions. Based on only 22 months of data, the GDR2 has limitations. But its combination with the HIPPARCOS catalog results in very high accuracy PMa vectors, that already enable us to set valuable constraints on the binarity of nearby objects. The detection of tangential velocity anomalies at a median accuracy of σ(ΔvT) = 1.0 m s−1 per parsec of distance is already possible with the GDR2. This type of analysis opens the possibility to identify long period orbital companions otherwise inaccessible. For long orbital periods, Gaia’s complementarity to radial velocity and transit techniques (that are more sensitive to short orbital periods) already appears to be remarkably powerful.

scholarly journals The Compositional Diversity of Low-Mass Exoplanets

2019 ◽  
Vol 47 (1) ◽  
pp. 141-171 ◽  
Author(s):  
Daniel Jontof-Hutter
Keyword(s):  
Bulk Composition ◽  
Diverse Range ◽  
Kepler Mission ◽  
Low Mass ◽  
Orbital Periods ◽  
Gaseous Atmospheres ◽  
The Masses ◽  
Compositional Diversity ◽  
Rocky Planets ◽  
Observational Techniques

Low-mass planets have an extraordinarily diverse range of bulk compositions, from primarily rocky worlds to those with deep gaseous atmospheres. As techniques for measuring the masses of exoplanets advance the field toward the regime of rocky planets, from ultrashort orbital periods to Venus-like distances, we identify the bounds on planet compositions, where sizes and incident fluxes inform bulk planet properties. In some cases, the precision of measurement of planet masses and sizes is approaching the theoretical uncertainties in planet models. An emerging picture explains aspects of the diversity of low-mass planets, although some problems remain: Do extreme low-density, low-mass planets challenge models of atmospheric mass loss? Are planet sizes strictly separated by bulk composition? Why do some stellar characterizations differ between observational techniques? With the Transiting Exoplanet Survey Satellite ( TESS) mission, low-mass exoplanets around the nearest stars will soon be discovered and characterized with unprecedented precision, permitting more detailed planetary modeling and atmospheric characterization of low-mass exoplanets than ever before. ▪ Following the Kepler mission, studies of exoplanetary compositions have entered the terrestrial regime. ▪ Low-mass planets have an extraordinary range of compositions, from Earth-like mixtures of rock and metal to mostly tenuous gas. ▪ The TESS mission will discover low-mass planets that can be studied in more detail than ever before.

scholarly journals Close-In Substellar Companions and the Formation of sdB-Type Close Binary Stars

2015 ◽  
Vol 2 (1) ◽  
pp. 183-187 ◽  
Author(s):  
L. Y. Zhu ◽  
S. B. Qian ◽  
E.-G. Zhao ◽  
E. Fernández Lajús ◽  
Z.-T. Han
Keyword(s):  
Binary Stars ◽  
Eclipsing Binaries ◽  
Close Binary ◽  
Close Binaries ◽  
Close Binary Stars ◽  
Cataclysmic Binaries ◽  
Low Mass ◽  
Substellar Companions ◽  
Orbital Periods

The sdB-type close binaries are believed to have experienced a common-envelope phase and may evolve into cataclysmic binaries (CVs). About 10% of all known sdB binaries are eclipsing binaries consisting of very hot subdwarf primaries and low-mass companions with short orbital periods. The eclipse profiles of these systems are very narrow and deep, which benefits the determination of high precise eclipsing times and makes the detection of small and close-in tertiary bodies possible. Since 2006 we have monitored some sdB-type eclipsing binaries to search for the close-in substellar companions by analyzing the light travel time effect. Here some progresses of the program are reviewed and the formation of sdB-type binary is discussed.

scholarly journals The B-Star Exoplanet Abundance Study: a co-moving 16–25 MJup companion to the young binary system HIP 79098

2019 ◽  
Vol 626 ◽  
pp. A99 ◽  
Author(s):  
Markus Janson ◽  
Ruben Asensio-Torres ◽  
Damien André ◽  
Mickaël Bonnefoy ◽  
Philippe Delorme ◽  
...  
Keyword(s):  
Proper Motion ◽  
Massive Stars ◽  
Brown Dwarfs ◽  
Mass Ratio ◽  
Low Mass Stars ◽  
Spectroscopic Binary ◽  
Bona Fide ◽  
Low Mass ◽  
Substellar Companions ◽  
Dependent Mass

Wide low-mass substellar companions are known to be very rare among low-mass stars, but appear to become increasingly common with increasing stellar mass. However, B-type stars, which are the most massive stars within ~150 pc of the Sun, have not yet been examined to the same extent as AFGKM-type stars in that regard. In order to address this issue, we launched the ongoing B-star Exoplanet Abundance Study (BEAST) to examine the frequency and properties of planets, brown dwarfs, and disks around B-type stars in the Scorpius-Centaurus (Sco-Cen) association; we also analyzed archival data of B-type stars in Sco-Cen. During this process, we identified a candidate substellar companion to the B9-type spectroscopic binary HIP 79098 AB, which we refer to as HIP 79098 (AB)b. The candidate had been previously reported in the literature, but was classified as a background contaminant on the basis of its peculiar colors. Here we demonstrate that the colors of HIP 79098 (AB)b are consistent with several recently discovered young and low-mass brown dwarfs, including other companions to stars in Sco-Cen. Furthermore, we show unambiguous common proper motion over a 15-yr baseline, robustly identifying HIP 79098 (AB)b as a bona fide substellar circumbinary companion at a 345 ± 6 AU projected separation to the B9-type stellar pair. With a model-dependent mass of 16–25 MJup yielding a mass ratio of <1%, HIP 79098 (AB)b joins a growing number of substellar companions with planet-like mass ratios around massive stars. Our observations underline the importance of common proper motion analysis in the identification of physical companionship, and imply that additional companions could potentially remain hidden in the archives of purely photometric surveys.

scholarly journals THE BROWN DWARF KINEMATICS PROJECT. II. DETAILS ON NINE WIDE COMMON PROPER MOTION VERY LOW MASS COMPANIONS TO NEARBY STARS,

2009 ◽  
Vol 139 (1) ◽  
pp. 176-194 ◽  
Author(s):  
Jacqueline K. Faherty ◽  
Adam J. Burgasser ◽  
Andrew A. West ◽  
John J. Bochanski ◽  
Kelle L. Cruz ◽  
...  
Keyword(s):  
Proper Motion ◽  
Brown Dwarf ◽  
Nearby Stars ◽  
Low Mass

scholarly journals Astrometric detection and characterization of brown dwarfs

2007 ◽  
Vol 3 (S248) ◽  
pp. 30-35
Author(s):  
R.-D. Scholz ◽  
M. J. McCaughrean ◽  
S. Röser ◽  
E. Schilbach
Keyword(s):  
Proper Motion ◽  
Near Infrared ◽  
Critical Mass ◽  
Brown Dwarfs ◽  
Solar Neighborhood ◽  
Sky Survey ◽  
Nearby Stars ◽  
Rare Class ◽  
Low Mass

AbstractAs a result of failed star formation, brown dwarfs (BDs) do not reach the critical mass to ignite the fusion of hydrogen in their cores. Different from their low-mass stellar brothers, the red dwarfs, BDs cool down with their lifetime to very faint magnitudes. Therefore, it was only about 10 to 20 years ago that such ultracool objects began to be detected. Accurate astrometry can be used to detect them indirectly as companions to stars by the signature of the so-called astrometric wobble. Resolved faint BD companions of nearby stars can be identified by their common proper motion (CPM). A direct astrometric detection of the hidden isolated BDs in the Solar neighborhood is possible with deep high proper motion (HPM) surveys. This technique led to the discovery of the first free-floating BD, Kelu 1, and of the nearest BD, ε Indi B. Both were meanwhile found to be binary BDs. The astrometric orbital monitoring of ε Indi Ba+Bb, for which we know an accurate distance from the Hipparcos measurement of its primary, ε Indi A, will allow the determination of individual masses of two low-mass BDs. Hundreds of BDs have been identified for the last decade. Deep optical sky survey (SDSS) and near-infrared sky surveys (DENIS, 2MASS), played a major role in the search mainly based on colours, since BDs emit most of their light at longer wavelengths. However, alternative deep optical HPM surveys based on archival photographic data are not only sensitive enough to detect some of the nearest representatives, they do also uncover many of the rare class of ultracool halo objects crossing the Solar neighborhood at large velocities. SSSPM 1444, with the extremely large proper motion of 3.5 arcsec/yr, is one of the nearest among these subdwarfs with masses at the substellar boundary. We present preliminary parallax results for this and two other ultracool subdwarfs (USDs) from the Calar Alto Omega 2000 parallax program.

scholarly journals Detection of planet candidates around K giants. HD 40956, HD 111591, and HD 113996

2018 ◽  
Vol 610 ◽  
pp. A3 ◽  
Author(s):  
G. Jeong ◽  
B.-C. Lee ◽  
I. Han ◽  
M. Omiya ◽  
H. Izumiura ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Astronomy Observatory ◽  
Giant Stars ◽  
Long Period ◽  
Substellar Companions ◽  
Optical Astronomy ◽  
K Giants

Aims. The purpose of this paper is to detect and investigate the nature of long-term radial velocity (RV) variations of K-type giants and to confirm planetary companions around the stars. Methods. We have conducted two planet search programs by precise RV measurement using the 1.8 m telescope at Bohyunsan Optical Astronomy Observatory (BOAO) and the 1.88 m telescope at Okayama Astrophysical Observatory (OAO). The BOAO program searches for planets around 55 early K giants. The OAO program is looking for 190 G–K type giants. Results. In this paper, we report the detection of long-period RV variations of three K giant stars, HD 40956, HD 111591, and HD 113996. We investigated the cause of the observed RV variations and conclude the substellar companions are most likely the cause of the RV variations. The orbital analyses yield P = 578.6 ± 3.3 d, m sin i = 2.7 ± 0.6 MJ, a = 1.4 ± 0.1 AU for HD 40956; P = 1056.4 ± 14.3 d, m sin i = 4.4 ± 0.4 MJ, a = 2.5 ± 0.1 AU for HD 111591; P = 610.2 ± 3.8 d, m sin i = 6.3 ± 1.0 MJ, a = 1.6 ± 0.1 AU for HD 113996.

scholarly journals Recovery of Old Novae

2004 ◽  
Vol 194 ◽  
pp. 187-189
Author(s):  
L. Schmidtobreick ◽  
C. Tappert ◽  
R. E. Mennickent ◽  
A. Bianchini
Keyword(s):  
Mass Transfer ◽  
Optical Spectroscopy ◽  
Classical Novae ◽  
First Results ◽  
Multi Wavelength ◽  
Low Mass ◽  
Orbital Periods

AbstractIn the course of a long-term project investigating classical novae with large outburst amplitudes, we have performed multi-wavelength photometry and optical spectroscopy of several old nova candidates. We here introduce the aim of the project, the search for low mass-transfer novae with short orbital periods, and explain the method to recover these old novae via their colour characteristics. Finally we concentrate on first results for selected objects in our sample.

scholarly journals Influence of the initial orbital period and accretion efficiency on the low-mass binary evolution

2021 ◽  
pp. 25-30
Author(s):  
J. Petrovic
Keyword(s):  
Mass Transfer ◽  
Orbital Period ◽  
White Dwarf ◽  
Binary Systems ◽  
Evolutionary Models ◽  
Stable Case ◽  
Long Period ◽  
Low Mass ◽  
Orbital Periods ◽  
Binary Evolution

This paper presents detailed evolutionary models of low-mass binary systems (1.25 + 1 M?) with initial orbital periods of 10, 50 and 100 days and accretion efficiency of 10%, 20%, 50%, and a conservative assumption. All models are calculated with the MESA (Modules for Experiments in Stellar Astrophysics) evolutionary code. We show that such binary systems can evolve via a stable Case B mass transfer into long period helium white dwarf systems.

scholarly journals LIStEN: L′ band Imaging Survey for Exoplanets in the North

2021 ◽  
Vol 645 ◽  
pp. A88
Author(s):  
Arianna Musso Barcucci ◽  
Ralf Launhardt ◽  
André Müller ◽  
Grant M. Kennedy ◽  
Roy van Boekel ◽  
...  
Keyword(s):  
Proper Motion ◽  
Major Axis ◽  
Mass Detection ◽  
Semi Major Axis ◽  
Simultaneous Imaging ◽  
The North ◽  
Nearby Stars ◽  
Low Mass ◽  
Differential Imaging ◽  
By Products

Context. Planetary systems and debris discs are natural by-products of the star formation process, and they affect each other. The direct imaging technique allows simultaneous imaging of both a companion and the circumstellar disc it resides in, and is thus a valuable tool to study companion-disc interactions. However, the number of systems in which a companion and a disc have been detected at the same time remains low. Aims. Our aim is to increase this sample, and to continue detecting and studying the population of giant planets in wide orbits. Methods. We carry out the L′ band Imaging Survey for Exoplanets in the North (LIStEN), which targeted 28 nearby stars: 24 are known to harbour a debris disc (DD) and the remaining 4 are protoplanetary disc-hosting stars. We aim to detect possible new companions, and study the interactions between the companion and their discs. Angular differential imaging observations were carried out in the L′ band at 3.8 μm using the LMIRCam instrument at the LBT, between October 2017 and April 2019. Results. No new companions were detected. We combined the derived mass detection limits with information on the disc, and on the proper motion of the host star, to constrain the presence of unseen planetary and low-mass stellar companion around the 24 disc-hosting stars in our survey. We find that 2 have an uncertain DD status and the remaining 22 have disc sizes compatible with self-stirring. Three targets show a proper motion anomaly (PMa) compatible with the presence of an unseen companion. Conclusions. Our achieved mass limits combined with the PMa analysis for HD 113337 support the presence of a second companion around the star, as suggested in previous RV studies. Our mass limits also help to tighten the constraints on the mass and semi-major axis of the unseen companions around HD 161868 and HD 8907.

scholarly journals 14 Her: A Likely Case of Planet–Planet Scattering

2021 ◽  
Vol 922 (2) ◽  
pp. L43
Author(s):  
Daniella C. Bardalez Gagliuffi ◽  
Jacqueline K. Faherty ◽  
Yiting Li ◽  
Timothy D. Brandt ◽  
Lauryn Williams ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Proper Motion ◽  
Motion Vector ◽  
Giant Planets ◽  
Middle Aged ◽  
Partial Phase ◽  
Current Configuration ◽  
Orbital Parameters ◽  
Long Term Trends

Abstract In this Letter, we measure the full orbital architecture of the two-planet system around the nearby K0 dwarf 14 Herculis. 14 Her (HD 145675, HIP 79248) is a middle-aged ( 4.6 − 1.3 + 3.8 Gyr) K0 star with two eccentric giant planets identified in the literature from radial velocity (RV) variability and long-term trends. Using archival RV data from Keck/HIRES in concert with Gaia-Hipparcos acceleration in the proper motion vector for the star, we have disentangled the mass and inclination of the b planet to 9.1 − 1.1 + 1.0 M Jup and 32.7 − 3.2 + 5.3 degrees. Despite only partial phase coverage for the c planet’s orbit, we are able to constrain its mass and orbital parameters as well to 6.9 − 1.0 + 1.7 M Jup and 101 − 33 + 31 degrees. We find that coplanarity of the b and c orbits is strongly disfavored. Combined with the age of the system and the comparable masses of its planets, this suggests that planet–planet scattering may be responsible for the current configuration of the system.

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