scholarly journals The Census of Exoplanets in Visual Binaries: Population Trends from a Volume-Limited Gaia DR2 and Literature Search

Author(s):  
Clémence Fontanive ◽  
Daniella Bardalez Gagliuffi

We present results from an extensive search in the literature and Gaia DR2 for visual co-moving binary companions to stars hosting exoplanets and brown dwarfs within 200 pc. We found 218 planet hosts out of the 938 in our sample to be part of multiple-star systems, with 10 newly discovered binaries and 2 new tertiary stellar components. This represents an overall raw multiplicity rate of 23.2 ± 1.6 % for hosts to exoplanets across all spectral types, with multi-planet systems found to have a lower stellar duplicity frequency at the 2.2-σ level. We found that more massive hosts are more often in binary configurations, and that planet-bearing stars in multiple systems are predominantly observed to be the most massive component of stellar binaries. Investigations of the multiplicity of planetary systems as a function of planet mass and separation revealed that giant planets with masses above 0.1 MJup are more frequently seen in stellar binaries than small sub-Jovian planets with a 3.6-σ difference, a trend enhanced for the most massive (>7 MJup) short-period (<0.5 AU) planets and brown dwarf companions. Binarity was however found to have no significant effect on the demographics of low- mass planets (<0.1 MJup) or warm and cool gas giants (>0.5 AU). While stellar companion mass appears to have no impact on planet properties, binary separation seems to be an important factor in the resulting structure of planetary systems. Stellar companions on separations <1000 AU can play a role in the formation or evolution of massive, close-in planets, while planets in wider binaries show similar properties to planets orbiting single stars. Finally, our analyses indicate that numerous stellar companions on separations smaller than 1–3 arcsec likely remain undiscovered to this date. Continuous efforts to complete our knowledge of stellar multiplicity on separations of tens to hundreds of AU are essential to confirm the reported trends and further our understanding of the roles played by multiplicity on exoplanets.

2019 ◽  
Vol 485 (4) ◽  
pp. 4967-4996 ◽  
Author(s):  
C Fontanive ◽  
K Rice ◽  
M Bonavita ◽  
E Lopez ◽  
K Mužić ◽  
...  

ABSTRACT Stellar multiplicity is believed to influence planetary formation and evolution, although the precise nature and extent of this role remain ambiguous. We present a study aimed at testing the role of stellar multiplicity in the formation and/or evolution of the most massive, close-in planetary and substellar companions. Using past and new direct imaging observations, as well as the Gaia DR2 catalogue, we searched for wide binary companions to 38 stars hosting massive giant planets or brown dwarfs (M > 7 MJup) on orbits shorter than ∼1 au. We report the discovery of a new component in the WASP-14 system, and present an independent confirmation of a comoving companion to WASP-18. From a robust Bayesian statistical analysis, we derived a binary fraction of $79.0^{+13.2}_{-14.7}$ per cent between 20 and 10 000 au for our sample, twice as high as for field stars with a 3σ significance. This binary frequency was found to be larger than for lower-mass planets on similar orbits, and we observed a marginally higher binary rate for inner companions with periods shorter than 10 d. These results demonstrate that stellar companions greatly influence the formation and/or evolution of these systems, suggesting that the role played by binary companions becomes more important for higher-mass planets, and that this trend may be enhanced for systems with tighter orbits. Our analysis also revealed a peak in binary separation at 250 au, highlighting a shortfall of close binaries among our sample. This indicates that the mechanisms affecting planet and brown dwarf formation or evolution in binaries must operate from wide separations, although we found that the Kozai–Lidov mechanism is unlikely to be the dominant underlying process. We conclude that binarity plays a crucial role in the existence of very massive short-period giant planets and brown dwarf desert inhabitants, which are almost exclusively observed in multiple systems.


2019 ◽  
Vol 486 (3) ◽  
pp. 4144-4148
Author(s):  
R R Paudel ◽  
J E Gizis ◽  
A J Burgasser ◽  
C Hsu

ABSTRACT We report the identification of a very low mass new binary system 2MASS J10274572+0629104, based on Kepler K2 photometry and Gaia DR2 astrometry. It is located at a distance of 90.0 ± 2.9 pc. The K2 light curve is consistent with a beat pattern of two periodic signals, and using Lomb–Scargle periodogram, we find two rotation periods of 0.2114 ± 0.0002 and 0.2199 ± 0.0003 d. We conclude that these rotation periods arise from two stars with similar spectral types of M6, and have nearly equal luminosity. It is the first ultracool binary system to be identified based on beat patterns in the light curve. Near-infrared spectroscopy yields RV = −9.8 ± 0.6 km s−1, v sin i = 21.5 ± 1.1 km s−1, Teff = 3110 ± 40 K, and log g = 5.2 ± 0.2. The motions are consistent with a young age, as are the rotation periods, but the source does not appear to be part of any known moving group. Furthermore, we detected three strong white light flares in the K2 light curve, with estimated total (UV/optical/IR) energies of 2.6 × 1033, 5.0 × 1033, and 3.5 × 1033 erg, respectively.


2009 ◽  
Vol 5 (H15) ◽  
pp. 760-760
Author(s):  
H. Zinnecker

Massive stars are known to be multiple systems, often in tight, short-period OB stars binaries (SB1 and SB2, found by spectroscopic monitoring). However, little is known about low-mass companions to massive stars, such as A, F, and G stars with masses in the range of 1 to 3 solar masses. Yet systems of massive stars with wide low-mass companions (of the order of a few AU) must exist, for these are the progenitors of LMXB and HMXB (low-mass and high-mass X-ray binaries).


2020 ◽  
Vol 494 (4) ◽  
pp. 4891-4906
Author(s):  
F Marocco ◽  
R L Smart ◽  
E E Mamajek ◽  
L M Sarro ◽  
A J Burgasser ◽  
...  

ABSTRACT We present 10 new ultracool dwarfs in seven wide binary systems discovered using Gaia second data release data, identified as part of our Gaia Ultra-Cool Dwarf Sample project. The seven systems presented here include an L1 companion to the G5 IV star HD 164507, an L1: companion to the V478 Lyr AB system, an L2 companion to the metal-poor K5 V star CD-28 8692, an M9 V companion to the young variable K0 V star LT UMa, and three low-mass binaries consisting of late Ms and early Ls. The HD 164507, CD-28 8692, V478 Lyr, and LT UMa systems are particularly important benchmarks, because the primaries are well characterized and offer excellent constraints on the atmospheric parameters and ages of the companions. We find that the M8 V star 2MASS J23253550+4608163 is ∼2.5 mag overluminous compared to M dwarfs of similar spectral type, but at the same time it does not exhibit obvious peculiarities in its near-infrared spectrum. Its overluminosity cannot be explained by unresolved binarity alone. Finally, we present an L1+L2 system with a projected physical separation of 959 au, making this the widest L + L binary currently known.


2004 ◽  
Vol 191 ◽  
pp. 7-14 ◽  
Author(s):  
A. Tokovinin

AbstractThe statistics of stellar systems of multiplicity three and higher is reviewed. They are frequent, 0.15−0.25 of all stellar systems. Some 700 multiples are expected among the 3383 stars of spectral type F, G, and K within 50 pc, while only 76 of them are actually known. Many (if not all) close binaries have distant tertiary components, indicating that angular momentum exchange within multiple systems was probably critical in forming short-period binaries. The ratio of outer to inner periods in the best-studied nearby multiples and in low-mass pre-main sequence multiples does not exceed 104 at the formation epoch; larger ratios are produced by subsequent orbital evolution. All multiples with well-defined orbits are dynamically stable, the eccentricities of outer orbits obey the empirical stability limit Pout(1 – eout)3/Pin > 5 that is more strict than current theoretical limits. Relative orientation of orbits in triple stars shows some degree of alignment, especially in weakly-hierarchical systems. The statistics support the idea that most multiple stars originated from dynamical interactions in small clusters.


1998 ◽  
Vol 11 (1) ◽  
pp. 539-541
Author(s):  
F. Mignard

Abstract The Hipparcos Catalogue provides general astrometric and photometric information on double and multiple stars in specific fields of the main Catalogue and detailed data on the components in the various sections of a dedicated annex: the Double and Multiple Systems Annex (DMSA). Overall statistics of these solutions are presented for the 13211 entries of this annex and the different types of solutions are outlined.


1998 ◽  
Vol 11 (1) ◽  
pp. 371-371
Author(s):  
S. Narusawa ◽  
A. Yamasaki ◽  
Y. Nakamura

Although the evolution of binary systems has been qualitatively interpreted with the evolutionary scenario, the quantitative interpretation of any observed system is still unsatisfactory due to the difficulty of the quantitative treatment of mass and angular momentum transfer/loss. To reach a true understanding of the evolution of binary systems, we have to accumulate more observational evidence. So far, we have observed several binaries that are short-period and noncontact, and found the existence of extremely small-mass systems. In the present paper, we study another short-period (P=0.659d), noncontact, eclipsing binary system, V392 Ori. We have made photometric and spectroscopic observations of V392 Ori. The light curves are found to vary, suggesting the existence of circumstellar matter around the system. Combining the photometric and spectroscopic results, we obtain parameters describing the system; we find the mass of the primary component is only 0.6Mʘ- undermassive for its spectral and luminosity class A5V, suggesting that a considerable amount of its original mass has been lost from the system during the course of evolution. The low-mass problem is very important for investigation of the evolution of close binary systems: largemass loss within and/or after the main-sequence will have a significant influence on the future evolution of binary systems.


2010 ◽  
Vol 6 (S276) ◽  
pp. 221-224
Author(s):  
Eric B. Ford

AbstractRadial velocity surveys have discovered over 400 exoplanets. While measuring eccentricities of low-mass planets remains a challenge, giant exoplanets display a broad range of orbital eccentricities. Recently, spectroscopic measurements during transit have demonstrated that the short-period giant planets (“hot-Jupiters”) also display a broad range of orbital inclinations (relative to the rotation axis of the host star). Both properties pose a challenge for simple disk migration models and suggest that late-stage orbital evolution can play an important role in determining the final architecture of planetary systems. One possible formation mechanism for the inclined hot-Jupiters is some form of eccentricity excitation (e.g., planet scattering, secular perturbations due to a distant planet or wide binary) followed tidal circularization. The planet scattering hypothesis also makes predictions for the population of planets at large separations. Recent discoveries of planets on wide orbits via direct imaging and highly anticipated results from upcoming direct imaging campaigns are poised to provide a new type of constraint on planet formation. This proceedings describes recent progress in understanding the formation of giant exoplanets.


2017 ◽  
Vol 45 ◽  
pp. 1760023
Author(s):  
S. O. Kepler ◽  
Alejandra Daniela Romero ◽  
Ingrid Pelisoli ◽  
Gustavo Ourique

White dwarf stars are the final stage of most stars, born single or in multiple systems. We discuss the identification, magnetic fields, and mass distribution for white dwarfs detected from spectra obtained by the Sloan Digital Sky Survey up to Data Release 13 in 2016, which lead to the increase in the number of spectroscopically identified white dwarf stars from 5[Formula: see text]000 to 39[Formula: see text]000. This number includes only white dwarf stars with [Formula: see text], i.e., excluding the Extremely Low Mass white dwarfs, which are necessarily the byproduct of stellar interaction.


2010 ◽  
Vol 6 (S276) ◽  
pp. 485-486
Author(s):  
Anne-Sophie Maurin ◽  
Franck Selsis ◽  
Franck Hersant ◽  
Marco Delbò

AbstractDuring the last few years, observations have yielded an abundant population of short-period planets under 15 Earth masses. Among those, hot terrestrial exoplanets represent a key population to study the survival of dense atmospheres close to their parent star. Thermal emission from exoplanets orbiting low-mass stars will be observable with the next generation of infrared telescopes, in particular the JWST. In order to constrain planetary and atmospheric properties, we have developed models to simulate the variation of the infrared emission along the path of the orbit (IR phase curve) for both airless planets and planets with dense atmospheres. Here, we focus on airless planets and present preliminary results on the influence of orbital elements, planet rotation, surface properties and observation geometry. Then, using simulated noisy phase curves, we test the retrieval of planets' properties and identify the degeneracies.


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