2MASS J15491331-3539118: a new low-mass wide companion of the GQ Lup system
J. M. Alcalá, F. Z. Majidi, S. Desidera, A. Frasca, C. F. Manara, E. Rigliaco, R. Gratton, M. Bonnefoy, E. Covino, G. Chauvin, R. Claudi, V. D'Orazi, M. Langloi… 展开作者
J. M. Alcalá, F. Z. Majidi, S. Desidera, A. Frasca, C. F. Manara, E. Rigliaco, R. Gratton, M. Bonnefoy, E. Covino, G. Chauvin, R. Claudi, V. D'Orazi, M. Langlois, C. Lazzoni, D. Mesa, J. E. Schlieder, A. Vigan
Substellar companions at wide separation around stars hosting planets or brown dwarfs (BDs) yet close enough for their formation in the circumstellar disc are of special interest. In this letter we report the discovery of a wide (projected separation $\sim$16.0arcsec, or 2400 AU, and position angle 114.61$^\circ$) companion of the GQ Lup A-B system, most likely gravitationally bound to it. A VLT/X-Shooter spectrum shows that this star, 2MASS J15491331-3539118, is a bonafide low-mass ($\sim$0.15 M$_\odot$) young stellar object (YSO) with stellar and accretion/ejection properties typical of Lupus YSOs of similar mass, and with kinematics consistent with that of the GQ Lup A-B system. A possible scenario for the formation of the triple system is that GQ Lup A and 2MASS J15491331-3539118 formed by fragmentation of a turbulent core in the Lup I filament, while GQ Lup B, the BD companion of GQ Lup A at 0.7arcsec, formed in situ by the fragmentation of the circumprimary disc. The recent discoveries that stars form along cloud filaments would favour the scenario of turbulent fragmentation for the formation of GQ Lup A and 2MASS J15491331-3539118.
Multi-wavelength observations provide a complementary view of the formation of young directly-imaged planet-mass companions. We report the ALMA 1.3 mm and Magellan adaptive optics (MagAO) H-alpha, i', z', and Ys observations of the GQ Lup system, a classical T Tauri star with a 10-40 Mjup substellar companion at ~110 AU projected separation. We estimate the accretion rates for both components from the observed H-alpha fluxes. In our 0.05 arcsec resolution ALMA map, we resolve GQ Lup A's disk in dust continuum, but no signal is found from the companion. The disk is compact, with a radius of ~22…
GQ Lup B is a young and accreting, substellar companion that appears to drive a spiral arm in the circumstellar disk of its host star. We report high-contrast imaging observations of GQ Lup B with VLT/NACO at 4-5 $μ$m and medium-resolution integral field spectroscopy with VLT/MUSE. The optical spectrum is consistent with an M9 spectral type, shows characteristics of a low-gravity atmosphere, and exhibits strong H$α$ emission. The $H-M'$ color is $\gtrsim$1 mag redder than field dwarfs with similar spectral types and a detailed analysis of the spectral energy distribution (SED) from optical to …
We present ALMA observations of the GQ Lup system, a young Sun-like star with a substellar mass companion in a wide-separation orbit. These observations of 870 $μ$m continuum and CO J=3-2 line emission with beam size $\sim0.3''$ ($\sim45$ AU) resolve the disk of dust and gas surrounding the primary star, GQ Lup A, and provide deep limits on any circumplanetary disk surrounding the companion, GQ Lup b. The circumprimary dust disk is compact with a FWHM of $59\pm12$ AU, while the gas has a larger extent with a characteristic radius of $46.5\pm1.8$ AU. By forward-modeling the velocity field of th…
We present Submillimeter Array observations of the GQ Lup system at 1.3 millimeters wavelength with $0\farcs4$ ($\sim$60 AU) resolution. Emission is detected from the position of the primary star, GQ Lup A, and is marginally resolved. No emission is detected from the substellar companion, GQ Lup B, $0\farcs7$ away. These data, together with models of the spectral energy distribution, suggest a compact disk around GQ Lup A with mass $\sim 3$ M$_{Jup}$, perhaps truncated by tidal forces. There is no evidence for a gap or hole in the disk that might be the signature of an additional inner compani…
Very recently, a second companion on wider orbit has been discovered around GQ Lup. This is a low-mass accreting star partially obscured by a disk seen at high inclination. If detected, this disk may be compared to the known disk around the primary. We detected this disk on archive HST and WISE data. The extended spectral energy distribution provided by these data confirms the presence of accretion from Halpha emission and UV excess, and shows an IR excess attributable to a warm disk. In addition, we resolved the disk on the HST images. This is found to be roughly aligned with the disk of the …
We present results from a near-infrared (NIR) adaptive optics (AO) survey of pre-main-sequence stars in the Lupus Molecular Cloud with VLT/NACO to identify (sub)stellar companions down to $\sim$20 au separation and investigate the effects of multiplicity on circumstellar disc properties. We observe for the first time in the NIR with AO a total of 47 targets and complement our observations with archival data for another 58 objects previously observed with the same instrument. All 105 targets have millimetre ALMA data available, which provide constraints on disc masses and sizes. We identify a t…
EX Lup-type objects (EXors) are low-mass pre-main sequence objects characterized by outbursts attributed to highly enhanced disk accretion. The trigger mechanism of EXor outbursts is still debated. One theory requires a close (sub)stellar companion that perturbs the inner disk and triggers the onset of the outburst. Here, we study the radial velocity (RV) variations of EX Lup, the prototype of EXors. We conducted a 5-year RV survey with HARPS and FEROS. We analyzed the activity of EX Lup by checking the bisector and several other activity indicators. We complemented the RV data with photometri…
The formation of massive planetary or brown dwarf companions at large projected separations from their host star is not yet well understood. In order to put constraints on formation scenarios we search for signatures in the orbit dynamics of the systems. We are specifically interested in the eccentricities and inclinations since those parameters might tell us about the dynamic history of the systems and where to look for additional low-mass sub-stellar companions. For this purpose we utilized VLT/NACO to take several well calibrated high resolution images of 6 target systems and analyze them t…
EX Lupi is a young star, prototype of EXor variables. Its spectrum is very rich in emission lines, including many metallic lines. It has been also proposed to have a close companion. We use the metallic emission lines to study the accretion structures and to test the companion hypothesis. We analyse 54 spectra taken in 5 years of quiescence time. We study the line profile variability and the radial velocity of the metallic emission lines. We use the velocity signatures of different species with various excitation conditions and their time dependency to track the dynamics associated to accretio…
EX Lup is a well-studied T Tauri star that represents the prototype of young eruptive stars EXors. In this paper we analyze new adaptive optics imaging and spectroscopic observations of EX Lup and its circumstellar environment in near-infrared in its quiescent phase. We observed EX Lup with the high contrast imager SPHERE/IRDIS in the dual-beam polarimetric imaging mode to resolve the circumstellar environment in near-infrared scattered light. We complemented these data with earlier SINFONI spectroscopy. We resolve for the first time in scattered light a compact feature around EX Lup azimuthal…
Previous star formation studies have, out of necessity, often defined a population of young stars confined to the proximity of a molecular cloud. Gaia allows us to examine a wider, three-dimensional structure of nearby star forming regions, leading to a new understanding of their history. We present a wide-area survey covering 494 square degrees of the Lupus complex, a prototypical low-mass star forming region. Our survey includes all known molecular clouds in this region as well as parts of the Upper Scorpius (US) and Upper Centaurus Lupus (UCL) groups of the Sco-Cen complex. We combine Gaia …
The radial transport, or drift, of dust has taken a critical role in giant planet formation theory. However, it has been challenging to identify dust drift pile ups in the hard-to-observe inner disk. We find that the IM Lup disk shows evidence that it has been shaped by an episode of dust drift. Using radiative transfer and dust dynamical modeling we study the radial and vertical dust distribution. We find that high dust drift rates exceeding 110 M_earth/Myr are necessary to explain both the dust and CO observations. Furthermore, the bulk of the large dust present in the inner 20 au needs to b…
We use two-dimensional Fourier transformation to measure the pitch angle ($φ$) of the dominant spiral Fourier mode of well-defined spiral arms in 13 protoplanetary disks, making use of near-infrared scattered-light images of AB Aur, SAO 206462, MWC 758, V1247 Ori, HD 142527, DZ Cha, LkH$α$ 330, and HD 100453, and ALMA millimeter continuum images of Elias 2-27, IM Lup, AS 205, and HT Lup. We find that the measured pitch angle correlates strongly with disk mass ($M_{D}$), such that more massive protoplanetary disks have smaller pitch angles, following $|φ| = -(7.8\pm1.7)\log(M_{D}/M_{\odot})+(2.…
Measurements of accretion rates onto planetary mass objects may distinguish between different planet formation mechanisms, which predict different accretion histories. In this Letter, we use \HST/WFC3 UVIS optical photometry to measure accretion rates onto three accreting objects, GSC06214-00210 b, GQ Lup b, and DH Tau b, that are at the planet/brown dwarf boundary and are companions to solar mass stars. The excess optical emission in the excess accretion continuum yields mass accretion rates of $10^{-9}$ to $10^{-11}$ \Msol/yr for these three objects. Their accretion rates are an order of mag…
In recent years a correlation between mass accretion rates onto new-born stars and their proto-planetary disc masses was detected in nearby young star-forming regions. Although such a correlation can be interpreted as due to viscous-diffusion processes in the disc, highly-accreting sources with low disc masses in more evolved regions remain puzzling. In this paper, we hypothesise that the presence of a stellar companion truncating the disc can explain these outliers. Firstly, we searched the literature for information on stellar multiplicity in Lupus, Chamaeleon~I and Upper Sco, finding that r…
Thanks to large dedicated surveys, large-scale magnetic fields have been detected for about 10% of early-type stars. We aim to precisely characterize the large-scale magnetic field of the magnetic component of the wide binary $o$ Lup, by using high-resolution ESPaDOnS and HARPSpol spectropolarimetry to analyse the variability of the measured longitudinal magnetic field. In addition, we investigate the periodic variability using space-based photometry collected with the BRITE-Constellation by means of iterative prewhitening. The rotational variability of the longitudinal magnetic field indicate…
There is an ongoing debate on whether hot jupiter hosts are more likely to be found in wide binaries with separations of $\gtrsim 100$ AU. In this paper, we search for comoving, very wide companions with separations of $10^3-10^4$ AU for hot jupiter hosts and main-sequence contact binaries in Gaia DR2, and compare the very wide companion fractions with their object-by-object-matched field star samples. We find that $11.9\pm 2.5$% of hot jupiter hosts and $14.1\pm 1.0$% of contact binaries have companions at separations of $10^3-10^4$ AU. While the very wide companion fraction of hot jupiter ho…
The young (~16 Myr) pre-main-sequence star in Sco-Cen 1SWASP J140747.93-394542.6, hereafter referred to as J1407, underwent a deep eclipse in 2007 April, bracketed by several shallower eclipses in the surrounding 54 d. This has been interpreted as the first detection of an eclipsing ring system circling a substellar object (dubbed J1407b). We report on a search for this companion with Sparse Aperture Mask imaging and direct imaging with both the UT4 VLT and Keck telescopes. Radial velocity measurements of J1407 provide additional constraints on J1407b and on short period companions to the cent…
Statistics on the population of distant substellar companions to nearby stars
Université Joseph Ki-Zerbo（约瑟夫·基泽尔博大学）；Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange（蔚蓝海岸大学，蔚蓝海岸天文台，法国国家科学研究中心，拉格朗日实验室）；Institut Trottier de recherche sur les exoplanètes, Département de Physique, Université de Montréal（特罗蒂埃系外行星研究所，物理系，蒙特利尔大学）；Observatoire du Mont-Mégantic（梅冈蒂克山天文台）；SUPA, Institute for Astronomy, University of Edinburgh（苏格兰天体物理学联盟，爱丁堡大学天文学研究所）
Context: We studied numerically the formation of giant planet (GP) and brown dwarf (BD) embryos in gravitationally unstable protostellar disks and compared our findings with directly-imaged, wide-orbit (>= 50 AU) companions known to-date. The viability of the disk fragmentation scenario for the formation of wide-orbit companions in protostellar disks around (sub-)solar mass stars was investigated. Methods: We used numerical hydrodynamics simulations of disk formation and evolution with an accurate treatment of disk thermodynamics. The use of the thin-disk limit allowed us to probe the long-ter…
We explore the impact of outer stellar companions on the occurrence rate of giant planets detected with radial velocities. We searched for stellar and planetary companions to a volume-limited sample of solar-type stars within 25 pc. Using adaptive optics imaging from the Lick 3m and Palomar 200" Telescopes, we characterized the multiplicity of our sample stars, down to the bottom of the main sequence. With these data, we confirm field star multiplicity statistics from previous surveys. We combined three decades of radial velocity data from the California Planet Search with new RV data from Kec…
We present 11 candidate late-type companions to nearby stars identified with data from the Wide-field Infrared Survey Explorer (WISE) and the Two Micron All-Sky Survey (2MASS). Eight of the candidates are likely to be companions based on their common proper motions with the primaries. The remaining three objects are rejected as companions, one of which is a free-floating T7 dwarf. Spectral types are available for five of the companions, which consist of M2V, M8.5V, L5, T8, and T8. Based on their photometry, the unclassified companions are probably two mid-M dwarfs and one late-M/early-L dwarf.…
We have combined optical and NIR photometry from Pan-STARRS 1 and UKIDSS to search the young (5-10 Myr) star-forming region of Upper Scorpius for wide (~400-4000 AU) substellar companions down to ~5 Mjup. Our search is ~4mag deeper than previous work based on 2MASS. We identified several candidates around known stellar members using a combination of color selection and spectral energy distribution fitting. Our followup spectroscopy has identified two new companions as well as confirmed two companions previously identified from photometry, with spectral types of M7.5-M9 and masses of ~15-60 Mju…
We present the first multiplicity-dedicated long baseline optical interferometric survey of the Scorpius-Centaurus-Lupus-Crux association. We used the Sydney University Stellar Interferometer to undertake a survey for new companions to 58 Sco-Cen B- type stars and have detected 24 companions at separations ranging from 7-130mas, 14 of which are new detections. Furthermore, we use a Bayesian analysis and all available information in the literature to determine the multiplicity distribution of the 58 stars in our sample, showing that the companion frequency is F = 1.35 and the mass ratio distrib…
We present the discovery of a substellar companion to the primary host lens in the microlensing event MOA-2012-BLG-006. The companion-to-host mass ratio is 0.016, corresponding to a companion mass of $\approx8~M_{\rm Jup} (M_*/0.5M_\odot)$. Thus, the companion is either a high-mass giant planet or a low-mass brown dwarf, depending on the mass of the primary $M_*$. The companion signal was separated from the peak of the primary event by a time that was as much as four times longer than the event timescale. We therefore infer a relatively large projected separation of the companion from its host…
We present the results of a direct-imaging survey for very large separation ($>$100 au), companions around 95 nearby young K5-L5 stars and brown dwarfs. They are high-likelihood candidates or confirmed members of the young ($\lessapprox$150 Myr) $β$ Pictoris and AB Doradus moving groups (ABDMG) and the TW Hya, Tucana-Horologium, Columba, Carina, and Argus associations. Images in $i'$ and $z'$ filters were obtained with the Gemini Multi-Object Spectrograph (GMOS) on Gemini South to search for companions down to an apparent magnitude of $z'\sim$22-24 at separations $\gtrapprox$20" from the targe…
Dynamical Mass Constraints on Transition Disk Perturbers with the G23H Catalog
University of Victoria（维多利亚大学）；NRC Herzberg Astronomy and Astrophysics（国家研究委员会赫茨伯格天文学与天体物理学研究所）；Massachusetts Institute of Technology（麻省理工学院）；University of California, Los Angeles（加州大学洛杉矶分校）
Several detections of wide-orbit planet-mass/sub-stellar companions around young solar-like stars were reported in the last decade. The origin of those possible planets is still unclear but accretion tracers and VLT/SPHERE observations indicate that they are surrounded by circumplanetary material or even a circumplanetary disk. We want to investigate if the gas component of disks around wide-orbit companions is detectable with current and future (sub)mm telescopes and what constraints such gas observations can provide on the nature of the circumplanetary material and on the mass of the compani…
Close binaries suppress the formation of circumstellar (S-type) planets and therefore significantly bias the inferred planet occurrence rates and statistical trends. After compiling various radial velocity and high-resolution imaging surveys, we determine that binaries with a < 1 au fully suppress S-type planets, binaries with a = 10 au host close planets at 15% the occurrence rate of single stars, and wide binaries with a > 200 au have a negligible effect on close planet formation. We show that F = 43% +/- 7% of solar-type primaries do not host close planets due to suppression by close stella…
Direct imaging surveys have discovered wide-orbit planetary-mass companions that challenge existing models of both star and planet formation, but their demographics remain poorly sampled. We have developed an automated binary companion point spread function (PSF) fitting pipeline to take advantage of Spitzer's infrared sensitivity to planetary-mass objects and circum(sub)stellar disks, measuring photometry across the four IRAC channels of 3.6 $μ$m, 4.5 $μ$m, 5.8 $μ$m, and 8.0 $μ$m. We present PSF-fitting photometry of archival Spitzer/IRAC images for 11 young, low-mass ($M\sim0.044$-0.88 $M_{\…
We develop Bayesian statistical methods for discovering and assigning probabilities to non-random (e.g., physical) stellar companions. These companions are either presently bound or were previously bound. The probabilities depend on similarities in corrected proper motion parallel and perpendicular to the brighter component's motion, parallax, and the local phase-space density of field stars. Control experiments are conducted to understand the behavior of false positives. The technique is applied to the Hipparcos Catalogue within 100 pc. This is the first all-sky survey to locate escaped compa…
(Abridged) Our aim is to identify analogues of gas giant planets, as companions at wide separations of very young stars. To identify these objects, we cross correlated the Visible and Infrared Survey Telescope for Astronomy (VISTA) Hemisphere Survey (VHS) and the United Kingdom Infrared Telescope Infrared Deep Sky Survey Galactic Clusters Survey (UKIDSS GCS) catalogues to search for common proper motion companions to 1195 already known members of Upper Scorpius (USco; age $\sim$5-10 Myr, distance $\sim$145 pc). We present the discovery and spectroscopic characterisation of two very wide subste…
The extrasolar planetary system around HR 8799 is the first multiplanet system ever imaged. It is also, by a wide margin, the highest mass system with >27 Jupiters of planetary mass past 25 AU. This is a remarkable system with no analogue with any other known planetary system. In the first part of this paper we investigate the nature of two faint objects imaged near the system. These objects are considerably fainter (H=20.4, and 21.6 mag) and more distant (projected separations of 612, and 534 AU) than the three known planetary companions b, c, and d (68-24 AU). It is possible that these two o…
We report the first results of a multi-epoch search for wide (separations greater than a few tens of AU), low-mass tertiary companions of a volume-limited sample of 118 known spectroscopic binaries within 30 pc of the Sun, using the 2MASS Point Source Catalog and follow-up observations with the KPNO and CTIO 4m telescopes. Note that this sample is not volume-complete but volume-limited, and, thus, there is incompleteness in our reported companion rates. We are sensitive to common proper motion companions with separations from roughly 200 AU to 10,000 AU (~10" -> ~10'). From 77 sources followed…
Aims. The project aims to understand better the role of wide brown dwarf companions on planetary systems. Methods. We obtained high-resolution spectra of six bright stars with co-moving wide substellar companions with the SONG, CARMENES, and STELLA high-resolution spectrographs. We used these spectra to derive radial velocities together with a complete set of stellar physical parameters. We then investigated radial velocities signals and discussed the fraction of planets in such systems. We also re-analyzed the ages of our targets, which were used to derive the physical parameters of wide brow…
We present the results of a survey to detect low-mass companions of UMa group members, carried out in 2003-2006 with NACO at the ESO VLT. While many extra-solar planets and planetary candidates have been found in close orbits around stars by the radial velocity and the transit method, direct detections at wider orbits are rare. The Ursa Major (UMa) group, a young stellar association at an age of about 200-600 Myr and an average distance of 25 pc, has not yet been addressed as a whole although its members represent a very interesting sample to search for and characterize sub-stellar companions …
A major outstanding question regarding the formation of planetary systems is whether wide-orbit giant planets form differently than close-in giant planets. We aim to establish constraints on two key parameters that are relevant for understanding the formation of wide-orbit planets: 1) the relative mass function and 2) the fraction of systems hosting multiple companions. In this study, we focus on systems with directly imaged substellar companions, and the detection limits on lower-mass bodies within these systems. First, we uniformly derive the mass probability distributions of known companion…
Even though tens of directly imaged companions have been discovered in the past decades, the number of directly confirmed multiplanet systems is still small. Dynamical analysis of these systems imposes important constraints on formation mechanisms of these wide-orbit companions. As part of the Young Suns Exoplanet Survey (YSES) we report the detection of a second planetary-mass companion around the 17 Myr-old, solar-type star TYC 8998-760-1 that is located in the Lower Centaurus Crux subgroup of the Scorpius-Centaurus association. The companion has a projected physical separation of 320 au and…
We analyze high quality, complete stellar catalogs for four young (roughly 1 Myr) and nearby (within ~300 pc) star-forming regions: Taurus, Lupus3, ChaI, and IC348, which have been previously shown to have stellar groups whose properties are similar to those of larger clusters such as the ONC. We find that stars at higher stellar surface densities within a region or belonging to groups tend to have a relative excess of more massive stars, over a wide range of masses. We find statistically significant evidence for this result in Taurus and IC348 as well as the ONC. These differences correspond …
We report the discovery of three planetary-mass companions (M = 6--20 $M_{Jup}$) in wide orbits ($ρ\sim$ 150--300 AU) around the young stars FW Tau (Taurus-Auriga), ROXs 12 (Ophiuchus), and ROXs 42B (Ophiuchus). All three wide planetary-mass companions ("PMCs") were reported as candidate companions in previous binary survey programs, but then were neglected for $>$10 years. We therefore obtained followup observations which demonstrate that each candidate is comoving with its host star. Based on the absolute $M_{K'}$ magnitudes, we infer masses (from hot-start evolutionary models) and projected…
We present the discovery of a co-moving planetary-mass companion ~42" (~2000 AU) from a young M3 star, GU Psc, likely member of the young AB Doradus Moving Group (ABDMG). The companion was first identified via its distinctively red i - z color (> 3.5) through a survey made with Gemini-S/GMOS. Follow-up Canada-France-Hawaii Telescope/WIRCam near-infrared (NIR) imaging, Gemini-N/GNIRS NIR spectroscopy and Wide-field Infrared Survey Explorer photometry indicate a spectral type of T3.5+-1 and reveal signs of low gravity which we attribute to youth. Keck/Adaptive Optics NIR observations did not res…
Instituto de Astrofísica de Canarias (IAC)（加那利天体物理研究所）；Universidad de La Laguna (ULL)（拉古纳大学）；The University of Western Ontario（韦仕敦大学）；Institute for Earth and Space Exploration, The University of Western Ontario（韦仕敦大学地球与空间探索研究所）
At wide separations, planetary-mass and brown dwarf companions to solar type stars occupy a curious region of parameters space not obviously linked to binary star formation or solar-system scale planet formation. These companions provide insight into the extreme case of companion formation (either binary or planetary), and due to their relative ease of observation when compared to close companions, they offer a useful template for our expectations of more typical planets. We present the results from an adaptive optics imaging survey for wide (50-500 AU) companions to solar type stars in Upper …
Over the past decade, the number of known wide binary systems has exponentially expanded thanks to the release of data from the Gaia Mission. Some of these wide binary systems are actually higher-order multiples, where one of the components is an unresolved binary itself. One way to search for these systems is by identifying overluminous components in the systems. In this study, we examine 4947 K+K wide binary pairs from the SUPERWIDE catalog and quantify the relative color and luminosity of the components to find evidence for additional, unresolved companions. The method is best illustrated i…
Abbreviated. We aim to identify new low-mass companions to young stars using the astrometric measurements provided by the Gaia space mission and complementary VLT/SPHERE data. We identify companion candidates from a sample of K-type, pre-main sequence stars in the Scorpius Centaurus association using the early version of the third data release of the Gaia space mission. Based on the provided positions, proper motions, and magnitudes, we identify all objects within a predefined radius whose differential proper motions are consistent with a gravitationally bound system. We derive companion masse…
Discovering wide companions of stellar systems allows us to constrain the dynamical environment and age of the latter. We studied four probable wide companions of four different stellar systems. The central stars are V4046 Sgr, HIP 74865, HIP 65426, and HIP 73145, and their probable wide companions are 2MASS J18152222-3249329, 2MASS J15174874-3028484, 2MASS J13242119-5129503, and 2MASS J14571503-3543505 respectively. V4046 Sgr is a member of $β$-Pictoris Moving Group while the rest of the stellar systems are acknowledged as members of the Scorpius-Centaurus association. The selected stellar sy…
In recent years there have been many attempts to characterize the occurrence of stellar, BD and planetary-mass companions to solar-type stars, with the aim of constraining formation mechanisms. From RV observations a dearth of companions with masses between 10-40 MJup has been noticed at close separations, suggesting the possibility of a distinct formation mechanism for objects above and below this range. We present a model for the substellar companion mass function (CMF). It consists of the superposition of the planet and BD companion mass distributions, assuming that we can extrapolate the R…
We present the discovery of a planetary-mass companion to CFHTWIR-Oph 98, a low-mass brown dwarf member of the young Ophiuchus star-forming region, with a wide 200-au separation (1.46 arcsec). The companion was identified using Hubble Space Telescope images, and confirmed to share common proper motion with the primary using archival and new ground-based observations. Based on the very low probability of the components being unrelated Ophiuchus members, we conclude that Oph 98 AB forms a binary system. From our multi-band photometry, we constrain the primary to be an M9-L1 dwarf, and the faint …
We present the largest sample of brown dwarf (BD) protoplanetary disk spectral energy distributions modeled to date. We compile 49 objects with ALMA observations from four star-forming regions: $ρ$ Ophiuchus, Taurus, Lupus, and Upper Scorpius. Studying multiple regions with various ages enables us to probe disk evolution over time. Specifically, from our models we obtain values for dust grain sizes, dust settling, and disk mass; we compare how each of these parameters vary between the regions. We find that disk mass decreases with age. We also find evidence of disk evolution (i.e., grain growt…
A catalog of common-proper-motion (CPM) companions to stars within 67 pc of the Sun is constructed based on the SUPERBLINK proper-motion survey. It contains 1392 CPM pairs with angular separations 30" < ρ< 1800", relative proper motion between the two components less than 25 mas/yr, magnitudes and colors of the secondaries consistent with those of dwarfs in the (M_V,V-J) diagram. In addition, we list 21 candidate white-dwarf CPM companions with separations under 300", about half of which should be physical. We estimate a 0.31 fraction of pairs with red-dwarf companions to be physical systems (…
We present a 3-5um LBT/MMT adaptive optics imaging study of three Upper Scorpius stars with brown dwarf (BD) companions with very low-masses/mass ratios (M_BD < 25M_Jup; M_BD / M_star ~ 1-2%), and wide separations (300-700 AU): GSC 06214, 1RXS 1609, and HIP 78530. We combine these new thermal IR data with existing 1-4um and 24um photometry to constrain the properties of the BDs and identify evidence for circumprimary/secondary disks in these unusual systems. We confirm that GSC 06214B is surrounded by a disk, further showing this disk produces a broadband IR excess due to small dust near the d…
We present moderate-resolution ($R$$\sim$4000-5000) near-infrared integral field spectroscopy of the young (1-5 Myr) 6-14 $M_\mathrm{Jup}$ companions ROXs 42B b and FW Tau b obtained with Keck/OSIRIS and Gemini-North/NIFS. The spectrum of ROXs 42B b exhibits clear signs of low surface gravity common to young L dwarfs, confirming its extreme youth, cool temperature, and low mass. Overall, it closely resembles the free-floating 4-7 $M_\mathrm{Jup}$ L-type Taurus member 2MASS J04373705+2331080. The companion to FW Tau AB is more enigmatic. Our optical and near-infrared spectra show strong evidenc…
The Young Suns Exoplanet Survey (YSES) consists of a homogeneous sample of 70 young, solar-mass stars located in the Lower Centaurus-Crux subgroup of the Scorpius-Centaurus association with an average age of $15\pm3\,$Myr. We report the detection of a co-moving companion around the K3IV star TYC 8998-760-1 (2MASSJ13251211-6456207) that is located at a distance of $94.6\pm0.3\,$pc using SPHERE/IRDIS on the VLT. Spectroscopic observations with VLT/X-SHOOTER constrain the mass of the star to $1.00\pm0.02\,M_{\odot}$ and an age of $16.7\pm1.4\,$Myr. The companion TYC 8998-760-1 b is detected at a …
AIMS: We checked a sample of 545 F stars within 50 pc for wide companions using existing near-infrared and optical sky surveys. METHODS: Applying the common proper motion (CPM) criterion, we detected wide companion candidates with 6-120 arcsec angular separations by visual inspection of multi-epoch finder charts and by searching in proper motion catalogues. Final proper motions were measured by involving positional measurements from up to eleven surveys. Spectral types of red CPM companions were estimated from their absolute $J$-band magnitudes based on the Hipparcos distances of the primaries…
