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Brendan P Bowler - One of the best experts on this subject based on the ideXlab platform.
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As the Worlds Turn: Constraining Spin Evolution in the Planetary-Mass Regime
arXiv: Earth and Planetary Astrophysics, 2020Co-Authors: Marta L Bryan, Brendan P Bowler, Caroline V. Morley, Sivan Ginzburg, Eugene Chiang, Jerry W. Xuan, Heather A KnutsonAbstract:To understand how Planetary spin evolves and traces planet formation processes, we measure rotational line broadening in eight Planetary-Mass objects (PMOs) of various ages (1--800 Myr) using near-infrared high-resolution spectra from NIRSPEC/Keck. Combining these with published rotation rates, we compile 27 PMO spin velocities, 16 of which derive from our NIRSPEC/Keck program. Our data are consistent with spin velocities $v$ scaling with Planetary radius $R$ as $v \propto 1/R$. We conclude that spin angular momentum is conserved as objects cool and contract over the sampled age range. The PMOs in our sample spin at rates that are approximately an order of magnitude below their break-up values, consistent with the hypothesis that they were spun down by magnetized circum-PMO disks (CPDs) during the formation era at ages $\lesssim$ a few Myr. There is a factor of 4--5 variation in spin velocity that has yet to be understood theoretically. It also remains to be seen whether spin evolves on timescales $\gtrsim$ 1 Gyr for PMOs, as it does for stars and high-Mass brown dwarfs emitting magnetized winds.
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ALMA 0.88 mm Survey of Disks around Planetary-Mass Companions
The Astronomical Journal, 2020Co-Authors: Brendan P Bowler, Gregory J. Herczeg, Adam L. Kraus, Patrick D. Sheehan, Sean M. Andrews, Luca Ricci, David J. Wilner, Zhaohuan ZhuAbstract:Characterizing the physical properties and compositions of circumPlanetary disks can provide important insights into the formation of giant planets and satellites. We report ALMA 0.88 mm (Band 7) continuum observations of six Planetary-Mass (10-20 $M_{\rm Jup}$) companions: CT Cha b, 1RXS 1609 b, ROXs 12 b, ROXs 42B b, DH Tau b, and FU Tau b. No continuum sources are detected at the locations of the companions down to 3$\sigma$ limits of 120-210 $\mu$Jy. Given these non-detections, it is not clear whether disks around Planetary-Mass companions indeed follow the disk flux-host Mass trend in the stellar regime. The faint radio brightness of these companion disks may result from a combination of fast radial drift and a lack of dust traps. Alternatively, as disks in binary systems are known to have significantly lower millimeter fluxes due to tidal interactions, these companion disks may instead follow the relationship of moderate-separation binary stars. This scenario can be tested with sensitive continuum imaging at rms levels of $\lesssim$10 $\mu$Jy.
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constraints on the spin evolution of young Planetary Mass companions
Nature Astronomy, 2018Co-Authors: Marta L Bryan, Bjorn Benneke, Heather A Knutson, Konstantin Batygin, Brendan P BowlerAbstract:Surveys of young star-forming regions have discovered a growing population of Planetary-Mass (<13 M_(Jup)) companions around young stars. There is an ongoing debate as to whether these companions formed like planets (that is, from the circumstellar disk), or if they represent the low-Mass tail of the star-formation process3. In this study, we utilize high-resolution spectroscopy to measure rotation rates of three young (2–300 Myr) Planetary-Mass companions and combine these measurements with published rotation rates for two additional companions to provide a picture of the spin distribution of these objects. We compare this distribution to complementary rotation-rate measurements for six brown dwarfs with Masses <20 M_(Jup), and show that these distributions are indistinguishable. This suggests that either these two populations formed via the same mechanism, or that processes regulating rotation rates are independent of formation mechanism. We find that rotation rates for both populations are well below their break-up velocities and do not evolve significantly during the first few hundred million years after the end of accretion. This suggests that rotation rates are set during the late stages of accretion, possibly by interactions with a circumPlanetary disk. This result has important implications for our understanding of the processes regulating the angular momentum evolution of young Planetary-Mass objects, and of the physics of gas accretion and disk coupling in the Planetary-Mass regime.
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constraints on the spin evolution of young Planetary Mass companions
arXiv: Earth and Planetary Astrophysics, 2017Co-Authors: Marta L Bryan, Bjorn Benneke, Heather A Knutson, Konstantin Batygin, Brendan P BowlerAbstract:Surveys of young star-forming regions have discovered a growing population of Planetary-Mass (<13 M_Jup) companions around young stars. There is an ongoing debate as to whether these companions formed like planets (that is, from the circumstellar disk), or if they represent the low-Mass tail of the star formation process. In this study we utilize high-resolution spectroscopy to measure rotation rates of three young (2-300 Myr) Planetary-Mass companions and combine these measurements with published rotation rates for two additional companions to provide a look at the spin distribution of these objects. We compare this distribution to complementary rotation rate measurements for six brown dwarfs with Masses <20 M_Jup, and show that these distributions are indistinguishable. This suggests that either that these two populations formed via the same mechanism, or that processes regulating rotation rates are independent of formation mechanism. We find that rotation rates for both populations are well below their break-up velocities and do not evolve significantly during the first few hundred million years after the end of accretion. This suggests that rotation rates are set during late stages of accretion, possibly by interactions with a circumPlanetary disk. This result has important implications for our understanding of the processes regulating the angular momentum evolution of young Planetary-Mass objects, and of the physics of gas accretion and disk coupling in the Planetary-Mass regime.
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Constraints on the Spin Evolution of Young Planetary-Mass Companions
arXiv: Earth and Planetary Astrophysics, 2017Co-Authors: Marta L Bryan, Bjorn Benneke, Heather A Knutson, Konstantin Batygin, Brendan P BowlerAbstract:Surveys of young star-forming regions have discovered a growing population of Planetary-Mass (
Adam L. Kraus - One of the best experts on this subject based on the ideXlab platform.
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ALMA 0.88 mm Survey of Disks around Planetary-Mass Companions
The Astronomical Journal, 2020Co-Authors: Brendan P Bowler, Gregory J. Herczeg, Adam L. Kraus, Patrick D. Sheehan, Sean M. Andrews, Luca Ricci, David J. Wilner, Zhaohuan ZhuAbstract:Characterizing the physical properties and compositions of circumPlanetary disks can provide important insights into the formation of giant planets and satellites. We report ALMA 0.88 mm (Band 7) continuum observations of six Planetary-Mass (10-20 $M_{\rm Jup}$) companions: CT Cha b, 1RXS 1609 b, ROXs 12 b, ROXs 42B b, DH Tau b, and FU Tau b. No continuum sources are detected at the locations of the companions down to 3$\sigma$ limits of 120-210 $\mu$Jy. Given these non-detections, it is not clear whether disks around Planetary-Mass companions indeed follow the disk flux-host Mass trend in the stellar regime. The faint radio brightness of these companion disks may result from a combination of fast radial drift and a lack of dust traps. Alternatively, as disks in binary systems are known to have significantly lower millimeter fluxes due to tidal interactions, these companion disks may instead follow the relationship of moderate-separation binary stars. This scenario can be tested with sensitive continuum imaging at rms levels of $\lesssim$10 $\mu$Jy.
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SEARCHING FOR SCATTERERS: HIGH-CONTRAST IMAGING OF YOUNG STARS HOSTING WIDE-SEPARATION Planetary-Mass COMPANIONS
The Astrophysical Journal, 2016Co-Authors: Marta L Bryan, Heather A Knutson, Brendan P Bowler, Adam L. Kraus, Sasha Hinkley, Dimitri Mawet, Eric L. Nielsen, Sarah BluntAbstract:We have conducted an angular differential imaging survey with NIRC2 at Keck in search of close-in substellar companions to a sample of seven systems with confirmed Planetary-Mass companions (PMCs) on wide orbits (>50 au). These wide-separation PMCs pose significant challenges to all three possible formation mechanisms: core accretion plus scattering, disk instability, and turbulent fragmentation. We explore the possibility that these companions formed closer in and were scattered out to their present-day locations by searching for other Massive bodies at smaller separations. The typical sensitivity for this survey is ΔK ~ 12.5 at 1". We identify eight candidate companions, whose Masses would reach as low as one Jupiter Mass if gravitationally bound. From our multi-epoch astrometry we determine that seven of these are conclusively background objects, while the eighth near DH Tau is ambiguous and requires additional monitoring. We rule out the presence of >7 M_(Jup) bodies in these systems down to 15–50 au that could be responsible for scattering. This result combined with the totality of evidence suggests that dynamical scattering is unlikely to have produced this population of PMCs. We detect orbital motion from the companions ROXs 42B b and ROXs 12 b, and from this determine 95% upper limits on the companions' eccentricities of 0.58 and 0.83 respectively. Finally, we find that the 95% upper limit on the occurrence rate of additional planets with Masses between 5 and 15 M_(Jup) outside of 40 au in systems with PMCs is 54%.
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searching for scatterers high contrast imaging of young stars hosting wide separation Planetary Mass companions
arXiv: Earth and Planetary Astrophysics, 2016Co-Authors: Marta L Bryan, Heather A Knutson, Brendan P Bowler, Adam L. Kraus, Sasha Hinkley, Dimitri Mawet, Eric L. Nielsen, Sarah BluntAbstract:We have conducted an angular differential imaging survey with NIRC2 at Keck in search of close-in substellar companions to a sample of seven systems with confirmed Planetary-Mass companions (PMCs) on wide orbits (>50 AU). These wide-separation PMCs pose significant challenges to all three possible formation mechanisms: core accretion plus scattering, disk instability, and turbulent fragmentation. We explore the possibility that these companions formed closer in and were scattered out to their present-day locations by searching for other Massive bodies at smaller separations. The typical sensitivity for this survey is \Delta K ~ 12.5 at 1". We identify eight candidate companions, whose Masses would reach as low as one Jupiter Mass if gravitationally bound. From our multi-epoch astrometry we determine that seven of these are conclusively background objects, while the eighth near DH Tau is ambiguous and requires additional monitoring. We rule out the presence of >7 M$_{\rm Jup}$ bodies in these systems down to 15 - 50 AU that could be responsible for scattering. This result combined with the totality of evidence suggests that dynamical scattering is unlikely to have produced this population of PMCs. We detect orbital motion from the companions ROXs 42B b and ROXs 12 b, and from this determine 95% upper limits on the companions' eccentricities of 0.58 and 0.83 respectively. Finally, we find that the 95% upper limit on the occurrence rate of additional planets with Masses between 5 - 15 M$_{\rm Jup}$ outside of 40 AU in systems with PMCs is 54%.
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ACCRETION ONTO Planetary Mass COMPANIONS OF LOW-Mass YOUNG STARS
The Astrophysical Journal, 2014Co-Authors: Yifan Zhou, Gregory J. Herczeg, Adam L. Kraus, Stanimir Metchev, Kelle L. CruzAbstract: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 Hubble Space Telescope (HST)/WFC3 UVIS optical photometry to measure accretion rates onto three accreting objects, GSC 06214–00210 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 10–9-10–11 M ☉ yr–1 for these three objects. Their accretion rates are an order of magnitude higher than expected from the correlation between Mass and accretion rates measured from the UV excess, which is applicable if these wide Planetary Mass companions formed by protostellar core fragmentation. The high accretion rates and large separation from the central star demonstrate the presence of Massive disks around these objects. Models for the formation and evolution of wide Planetary Mass companions should account for their large accretion rates. High ratios of Hα luminosity over accretion luminosity for objects with low accretion rates suggest that searches for Hα emission may be an efficient way to find accreting planets.
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accretion onto Planetary Mass companions of low Mass young stars
arXiv: Solar and Stellar Astrophysics, 2014Co-Authors: Yifan Zhou, Gregory J. Herczeg, Adam L. Kraus, Stanimir Metchev, Kelle L. CruzAbstract: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 magnitude higher than expected from the correlation between Mass and accretion rates measured from the UV excess, which is applicable if these wide Planetary Mass companions formed by protostellar core fragmentation. The high accretion rates and large separation from the central star demonstrate the presence of Massive disks around these objects. Models for the formation and evolution of wide Planetary Mass companions should account for their large accretion rates. High ratios of H$\alpha$ luminosity over accretion luminosity for objects with low accretion rates suggest that searches for H$\alpha$ emission may be an efficient way to find accreting planets.
Jonathan Gagné - One of the best experts on this subject based on the ideXlab platform.
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2Mass J13243553+6358281 is an Early T-Type Planetary-Mass Object in the AB Doradus Moving Group
The Astrophysical Journal, 2018Co-Authors: Jonathan Gagné, Katelyn N. Allers, Jacqueline K. Faherty, Daniella C. Bardalez Gagliuffi, Christopher A. Theissen, Étienne ArtigauAbstract:We present new radial velocity and trigonometric parallax measurements indicating that the unusually red and photometrically variable T2 dwarf 2Mass J13243553+6358281 is a member of the young (~150 Myr) AB Doradus moving group based on its space velocity. We estimate its model-dependent Mass in the range 11-12 $M_{\rm Jup}$ at the age of the AB Doradus moving group, and its trigonometric parallax distance of 12.7 $\pm$ 1.5 pc makes it one of the nearest known isolated Planetary-Mass objects. The unusually red continuum of 2Mass J13243553+6358281 in the near-infrared was previously suspected to be caused by an unresolved L+T brown dwarf binary, although it was never observed with high-spatial resolution imaging. This new evidence of youth suggests that a low surface gravity may be sufficient to explain this peculiar feature. Using the new parallax we find that its absolute $J$-band magnitude is ~0.4 mag fainter than equivalent-type field brown dwarfs, suggesting that the binary hypothesis is unlikely. The fundamental properties of 2Mass J13243553+6358281 follow the spectral type sequence of other known high-likelihood members of the AB Doradus moving group. The effective temperature of 2Mass J13243553+6358281 provides the first precise constraint on the L/T transition at a known young age, and indicates that it happens at a temperature of ~1150 K at ~150 Myr, compared to ~1250 K for field brown dwarfs.
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2Mass j13243553 6358281 is an early t type Planetary Mass object in the ab doradus moving group
arXiv: Solar and Stellar Astrophysics, 2018Co-Authors: Jonathan Gagné, Katelyn N. Allers, Jacqueline K. Faherty, Christopher A. Theissen, Daniella Bardalez C Gagliuffi, Étienne ArtigauAbstract:We present new radial velocity and trigonometric parallax measurements indicating that the unusually red and photometrically variable T2 dwarf 2Mass J13243553+6358281 is a member of the young (~150 Myr) AB Doradus moving group based on its space velocity. We estimate its model-dependent Mass in the range 11-12 $M_{\rm Jup}$ at the age of the AB Doradus moving group, and its trigonometric parallax distance of 12.7 $\pm$ 1.5 pc makes it one of the nearest known isolated Planetary-Mass objects. The unusually red continuum of 2Mass J13243553+6358281 in the near-infrared was previously suspected to be caused by an unresolved L+T brown dwarf binary, although it was never observed with high-spatial resolution imaging. This new evidence of youth suggests that a low surface gravity may be sufficient to explain this peculiar feature. Using the new parallax we find that its absolute $J$-band magnitude is ~0.4 mag fainter than equivalent-type field brown dwarfs, suggesting that the binary hypothesis is unlikely. The fundamental properties of 2Mass J13243553+6358281 follow the spectral type sequence of other known high-likelihood members of the AB Doradus moving group. The effective temperature of 2Mass J13243553+6358281 provides the first precise constraint on the L/T transition at a known young age, and indicates that it happens at a temperature of ~1150 K at ~150 Myr, compared to ~1250 K for field brown dwarfs.
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2Mass J11151597+1937266: A Young, Dusty, Isolated, Planetary-Mass Object with a Potential Wide Stellar Companion
The Astrophysical Journal, 2018Co-Authors: Christopher A. Theissen, Jonathan Gagné, Adam J Burgasser, Daniella C. Bardalez Gagliuffi, Kevin K. Hardegree-ullman, Sarah J. Schmidt, Andrew A. WestAbstract:We present 2Mass J11151597+1937266, a recently identified low-surface gravity L dwarf, classified as an L2$\gamma$ based on Sloan Digital Sky Survey optical spectroscopy. We confirm this spectral type with near-infrared spectroscopy, which provides further evidence that 2Mass J11151597+1937266 is a low-surface gravity L dwarf. This object also shows significant excess mid-infrared flux, indicative of circumstellar material; and its strong H$\alpha$ emission (EW$_{\mathrm{H}\alpha}=560\pm82$ \AA) is an indicator of enhanced magnetic activity or weak accretion. Comparison of its spectral energy distribution to model photospheres yields an effective temperature of $1724^{+184}_{-38}$ K. We also provide a revised distance estimate of $37\pm6$ pc using a spectral type-luminosity relationship for low-surface gravity objects. The 3-dimensional galactic velocities and positions of 2Mass J11151597+1937266 do not match any known young association or moving group. Assuming a probable age in the range of 5-45 Myr, the model-dependent estimated Mass of this object is between 7-21 $M_\mathrm{Jup}$, making it a potentially isolated Planetary-Mass object. We also identify a candidate co-moving, young stellar companion, 2Mass J11131089+2110086.
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A Search for Photometric Variability in the Young T3.5 Planetary-Mass Companion GU Psc b
The Astronomical Journal, 2017Co-Authors: Marie-eve Naud, Étienne Artigau, René Doyon, Lison Malo, Jonathan Gagné, Loic Albert, Jason F. Rowe, Sandie BouchardAbstract:We present a photometric $J$-band variability study of GU Psc b, a T3.5 co-moving Planetary-Mass companion (9-13$M_{\rm{Jup}}$) to a young ($\sim$150 Myr) M3 member of the AB Doradus Moving Group. The large separation between GU Psc b and its host star (42") provides a rare opportunity to study the photometric variability of a Planetary-Mass companion. The study presented here is based on observations obtained from 2013 to 2014 over three nights with durations of 5-6 hr each with the WIRCam imager at Canada-France-Hawaii Telescope. Photometric variability with a peak-to-peak amplitude of $4\pm1$% at a timescale of $\sim$6 hr was marginally detected on 2014 October 11. No high-significance variability was detected on 2013 December 22 and 2014 October 10. The amplitude and timescale of the variability seen here, as well as its evolving nature, is comparable to what was observed for a variety of field T dwarfs and suggests that mechanisms invoked to explain brown dwarf variability may be applicable to low-gravity objects such as GU Psc b. Rotation-induced photometric variability due to the formation and dissipation of atmospheric features such as clouds is a plausible hypothesis for the tentative variation detected here. Additional photometric measurements, particularly on longer timescales, will be required to confirm and characterize the variability of GU Psc b, determine its periodicity and to potentially measure its rotation period.
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PSYM-WIDE: A Survey for Large-separation Planetary-Mass Companions to Late Spectral Type Members of Young Moving Groups
The Astronomical Journal, 2017Co-Authors: Marie-eve Naud, Étienne Artigau, René Doyon, Lison Malo, Jonathan Gagné, David Lafrenière, Christian Wolf, E. A. MagnierAbstract:We present the results of a direct-imaging survey for very large separation ($>$100 au), companions around 95 nearby young K5-L5 stars and brown dwarfs. They are high-likelihood candidates or confirmed members of the young ($\lessapprox$150 Myr) $\beta$ 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 targets and in the remainder of the wide 5.5' $\times$ 5.5' GMOS field of view. This allowed us to probe the most distant region where Planetary-Mass companions could be gravitationally bound to the targets. This region was left largely unstudied by past high-contrast imaging surveys, which probed much closer-in separations. This survey led to the discovery of a Planetary-Mass (9-13 $\,M_{\rm{Jup}}$) companion at 2000 au from the M3V star GU Psc, a highly probable member of ABDMG. No other substellar companions were identified. These results allowed us to constrain the frequency of distant Planetary-Mass companions (5-13 $\,M_{\rm{Jup}}$) to 0.84$_{-0.66}^{+6.73}$% (95% confidence) at semimajor axes between 500 and 5000 au around young K5-L5 stars and brown dwarfs. This is consistent with other studies suggesting that gravitationally bound Planetary-Mass companions at wide separations from low-Mass stars are relatively rare.
Víctor J. S. Béjar - One of the best experts on this subject based on the ideXlab platform.
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Optical and Near-infrared Spectra of σ Orionis Isolated Planetary-Mass Objects
The Astrophysical Journal, 2017Co-Authors: M. R. Zapatero Osorio, Víctor J. S. Béjar, K. Peña RamírezAbstract:We have obtained low-resolution optical (0.7-0.98 micron) and near-infrared (1.11-1.34 micron and 0.8-2.5 micron) spectra of twelve isolated Planetary-Mass candidates (J = 18.2-19.9 mag) of the 3-Myr sigma Orionis star cluster with a view to determining the spectroscopic properties of very young, substellar dwarfs and assembling a complete cluster Mass function. We have classified our targets by visual comparison with high- and low-gravity standards and by measuring newly defined spectroscopic indices. We derived L0-L4.5 and M9-L2.5 using high- and low-gravity standards, respectively. Our targets reveal clear signposts of youth, thus corroborating their cluster membership and Planetary Masses (6-13 Mjup). These observations complete the sigma Orionis Mass function by spectroscopically confirming the Planetary-Mass domain to a confidence level of $\sim$75 percent. The comparison of our spectra with BT-Settl solar metallicity model atmospheres yields a temperature scale of 2350-1800 K and a low surface gravity of log g ~ 4.0 [cm/s2], as would be expected for young Planetary-Mass objects. We discuss the properties of the cluster least-Massive population as a function of spectral type. We have also obtained the first optical spectrum of S Ori 70, a T dwarf in the direction of sigma Orionis. Our data provide reference optical and near-infrared spectra of very young L dwarfs and a Mass function that may be used as templates for future studies of low-Mass substellar objects and exoplanets. The extrapolation of the sigma Orionis Mass function to the solar neighborhood may indicate that isolated Planetary-Mass objects with temperatures of 200-300 K and Masses in the interval 6-13-Mjup may be as numerous as very low-Mass stars.
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New Isolated Planetary-Mass Objects and the Stellar and Substellar Mass Function of the σ Orionis Cluster
The Astrophysical Journal, 2012Co-Authors: K. Peña Ramírez, M. R. Zapatero Osorio, Víctor J. S. Béjar, Monika G. Petr-gotzens, E. L. MartínAbstract:We report on our analysis of the VISTA Orion ZY JHK{sub s} photometric data (completeness magnitudes of Z = 22.6 and J = 21.0 mag) focusing on a circular area of 2798.4 arcmin{sup 2} around the young {sigma} Orionis star cluster ({approx}3 Myr, {approx}352 pc, and solar metallicity). The combination of the VISTA photometry with optical, WISE and Spitzer data allows us to identify a total of 210 {sigma} Orionis member candidates with Masses in the interval 0.25-0.004 M{sub Sun }, 23 of which are new Planetary-Mass object findings. These discoveries double the number of cluster Planetary-Mass candidates known so far. One object has colors compatible with a T spectral type. The {sigma} Orionis cluster harbors about as many brown dwarfs (69, 0.072-0.012 M{sub Sun }) and Planetary-Mass objects (37, 0.012-0.004 M{sub Sun }) as very low Mass stars (104, 0.25-0.072 M{sub Sun }). Based on Spitzer data, we derive a disk frequency of {approx}40% for very low Mass stars, brown dwarfs, and Planetary-Mass objects in {sigma} Orionis. The radial density distributions of these three Mass intervals are alike: all are spatially concentrated within an effective radius of 12' (1.2 pc) around the multiple star {sigma} Ori, and no obviousmore » segregation between disk-bearing and diskless objects is observed. Using the VISTA data and the Mayrit catalog, we derive the cluster Mass spectrum ({Delta}N/{Delta}M {approx} M{sup -{alpha}}) from {approx}19 to 0.006 M{sub Sun} (VISTA ZJ completeness), which is reasonably described by two power-law expressions with indices of {alpha} = 1.7 {+-} 0.2 for M > 0.35 M{sub Sun }, and {alpha} = 0.6 {+-} 0.2 for M < 0.35 M{sub Sun }. The {sigma} Orionis Mass spectrum smoothly extends into the Planetary-Mass regime down to 0.004 M{sub Sun }. Our findings of T-type sources (
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Search and characterization of T-type Planetary Mass candidates in the σ Orionis cluster
Proceedings of the International Astronomical Union, 2010Co-Authors: Karla Peña Ramírez, Maria Rosa Zapatero Osorio, Víctor J. S. BéjarAbstract:We present new photometric and astrometric data available for S Ori 70 and 73, the two T-type Planetary-Mass member candidates in the σ Orionis cluster (~3 ± 2 Myr, d~360 pc). S Ori 70 ( J ~ 19.9 mag) has a spectral type of T5.5 ± 1.0 measured from published near-infrared spectra, while no spectroscopic data are available for S Ori 73 ( J ~ 21 mag). We estimate the spectral type of S Ori 73 by using J , H , and CH 4off (λ c =1.575 μm, Δλ=0.112 μm) photometry and comparing the H - CH 4off index of S Ori 73 with the colors of field stars and brown dwarfs of spectral types in the range F to late T. The locations of S Ori 70 and 73 in the J - H vs H - CH 4off color-color diagram are consistent with spectral types T8 ± 1 and T4 ± 1, respectively. Proper motion measurements of the two sources are larger than the motion of the central σ Ori star, making their cluster membership somehow uncertain.
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Discs of Planetary-Mass objects in $\mathsf{\sigma}$ Orionis
Astronomy & Astrophysics, 2007Co-Authors: M. R. Zapatero Osorio, José A. Caballero, Víctor J. S. Béjar, Rafael Rebolo, D. Barrado Y Navascués, G. Bihain, J. Eislöffel, Eric Martin, Coryn A. L. Bailer-jones, Reinhard MundtAbstract:Aims.We searched for infrared flux excesses of Planetary-Mass candidates in the σ Orionis cluster (~3 Myr, ~350 pc). Methods: Using IJHKs data from the literature and the [3.6], [4.5], [5.8], and [8.0] IRAC images of the σ Orionis cluster from the Spitzer Space Telescope public archives, we constructed colour-colour diagrams and spectral energy distributions from 0.8 to 8.0 μm of cluster candidates fainter than J = 18.0 mag, i.e. the Planetary-Mass borderline for σ Orionis. Results: Infrared flux excesses are detected longward of 5 μm in seven objects (S Ori 54, 55, 56, 58, 60, S Ori J053956.8-025315 and S Ori J053858.6-025228) with Masses estimated in the range 7-14 M_Jup. Emission at shorter wavelengths (4.5 μm) in excess of the photosphere is probably observed in S Ori 56 and S Ori J053858.6-025228. The faintest and least Massive object, S Ori 60, exhibits flux excess only at 8 μm. We ascribe these infrared excesses to the presence of circumsubstellar warm discs, providing additional confirmation for the objects' membership of σ Orionis. The observed incidence of inner discs around Planetary-Mass objects is ≥50%, which is consistent with the measured inner disc frequency among cluster brown dwarfs and low-Mass stars, suggesting that these objects share a common origin. However, there is a trend for the inner disc rate to increase with decreasing Mass (from 10 Mȯ through the substellar domain), which may be due to a Mass-dependent timescale for the dissipation of the interior discs.
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The substellar Mass function in σ Orionis II. Optical, near-infrared and IRAC/Spitzer photometry of young cluster brown dwarfs and Planetary-Mass objects ,
Astronomy & Astrophysics, 2007Co-Authors: José A. Caballero, M. R. Zapatero Osorio, Víctor J. S. Béjar, Rafael Rebolo, D. Barrado Y Navascués, G. Bihain, Coryn A. L. Bailer-jones, Reinhard Mundt, J. Eislöffel, T. ForveilleAbstract:Aims. We investigate the Mass function in the substellar domain down to a few Jupiter Masses in the young σ Orionis open cluster (3 ± 2M a,d = 360 +70 −60 pc). Methods. We have performed a deep IJ-band search, covering an area of 790 arcmin 2 close to the cluster centre. This survey was complemented with an infrared follow-up in the HKs- and Spitzer 3.6–8.0 µm-bands. Using colour–magnitude diagrams, we have selected 49 candidate cluster members in the magnitude interval 16.1 mag < I < 23.0 mag. Results. Accounting for flux excesses at 8.0 µm and previously known spectral features of youth, we identify 30 objects as bona fide cluster members. Four are first identified from our optical-near infrared data. Eleven have most probable Masses below the deuterium burning limit which we therefore classify as candidate Planetary-Mass objects. The slope of the substellar Mass spectrum – –
Étienne Artigau - One of the best experts on this subject based on the ideXlab platform.
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2Mass J13243553+6358281 is an Early T-Type Planetary-Mass Object in the AB Doradus Moving Group
The Astrophysical Journal, 2018Co-Authors: Jonathan Gagné, Katelyn N. Allers, Jacqueline K. Faherty, Daniella C. Bardalez Gagliuffi, Christopher A. Theissen, Étienne ArtigauAbstract:We present new radial velocity and trigonometric parallax measurements indicating that the unusually red and photometrically variable T2 dwarf 2Mass J13243553+6358281 is a member of the young (~150 Myr) AB Doradus moving group based on its space velocity. We estimate its model-dependent Mass in the range 11-12 $M_{\rm Jup}$ at the age of the AB Doradus moving group, and its trigonometric parallax distance of 12.7 $\pm$ 1.5 pc makes it one of the nearest known isolated Planetary-Mass objects. The unusually red continuum of 2Mass J13243553+6358281 in the near-infrared was previously suspected to be caused by an unresolved L+T brown dwarf binary, although it was never observed with high-spatial resolution imaging. This new evidence of youth suggests that a low surface gravity may be sufficient to explain this peculiar feature. Using the new parallax we find that its absolute $J$-band magnitude is ~0.4 mag fainter than equivalent-type field brown dwarfs, suggesting that the binary hypothesis is unlikely. The fundamental properties of 2Mass J13243553+6358281 follow the spectral type sequence of other known high-likelihood members of the AB Doradus moving group. The effective temperature of 2Mass J13243553+6358281 provides the first precise constraint on the L/T transition at a known young age, and indicates that it happens at a temperature of ~1150 K at ~150 Myr, compared to ~1250 K for field brown dwarfs.
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2Mass j13243553 6358281 is an early t type Planetary Mass object in the ab doradus moving group
arXiv: Solar and Stellar Astrophysics, 2018Co-Authors: Jonathan Gagné, Katelyn N. Allers, Jacqueline K. Faherty, Christopher A. Theissen, Daniella Bardalez C Gagliuffi, Étienne ArtigauAbstract:We present new radial velocity and trigonometric parallax measurements indicating that the unusually red and photometrically variable T2 dwarf 2Mass J13243553+6358281 is a member of the young (~150 Myr) AB Doradus moving group based on its space velocity. We estimate its model-dependent Mass in the range 11-12 $M_{\rm Jup}$ at the age of the AB Doradus moving group, and its trigonometric parallax distance of 12.7 $\pm$ 1.5 pc makes it one of the nearest known isolated Planetary-Mass objects. The unusually red continuum of 2Mass J13243553+6358281 in the near-infrared was previously suspected to be caused by an unresolved L+T brown dwarf binary, although it was never observed with high-spatial resolution imaging. This new evidence of youth suggests that a low surface gravity may be sufficient to explain this peculiar feature. Using the new parallax we find that its absolute $J$-band magnitude is ~0.4 mag fainter than equivalent-type field brown dwarfs, suggesting that the binary hypothesis is unlikely. The fundamental properties of 2Mass J13243553+6358281 follow the spectral type sequence of other known high-likelihood members of the AB Doradus moving group. The effective temperature of 2Mass J13243553+6358281 provides the first precise constraint on the L/T transition at a known young age, and indicates that it happens at a temperature of ~1150 K at ~150 Myr, compared to ~1250 K for field brown dwarfs.
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A Search for Photometric Variability in the Young T3.5 Planetary-Mass Companion GU Psc b
The Astronomical Journal, 2017Co-Authors: Marie-eve Naud, Étienne Artigau, René Doyon, Lison Malo, Jonathan Gagné, Loic Albert, Jason F. Rowe, Sandie BouchardAbstract:We present a photometric $J$-band variability study of GU Psc b, a T3.5 co-moving Planetary-Mass companion (9-13$M_{\rm{Jup}}$) to a young ($\sim$150 Myr) M3 member of the AB Doradus Moving Group. The large separation between GU Psc b and its host star (42") provides a rare opportunity to study the photometric variability of a Planetary-Mass companion. The study presented here is based on observations obtained from 2013 to 2014 over three nights with durations of 5-6 hr each with the WIRCam imager at Canada-France-Hawaii Telescope. Photometric variability with a peak-to-peak amplitude of $4\pm1$% at a timescale of $\sim$6 hr was marginally detected on 2014 October 11. No high-significance variability was detected on 2013 December 22 and 2014 October 10. The amplitude and timescale of the variability seen here, as well as its evolving nature, is comparable to what was observed for a variety of field T dwarfs and suggests that mechanisms invoked to explain brown dwarf variability may be applicable to low-gravity objects such as GU Psc b. Rotation-induced photometric variability due to the formation and dissipation of atmospheric features such as clouds is a plausible hypothesis for the tentative variation detected here. Additional photometric measurements, particularly on longer timescales, will be required to confirm and characterize the variability of GU Psc b, determine its periodicity and to potentially measure its rotation period.
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PSYM-WIDE: A Survey for Large-separation Planetary-Mass Companions to Late Spectral Type Members of Young Moving Groups
The Astronomical Journal, 2017Co-Authors: Marie-eve Naud, Étienne Artigau, René Doyon, Lison Malo, Jonathan Gagné, David Lafrenière, Christian Wolf, E. A. MagnierAbstract:We present the results of a direct-imaging survey for very large separation ($>$100 au), companions around 95 nearby young K5-L5 stars and brown dwarfs. They are high-likelihood candidates or confirmed members of the young ($\lessapprox$150 Myr) $\beta$ 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 targets and in the remainder of the wide 5.5' $\times$ 5.5' GMOS field of view. This allowed us to probe the most distant region where Planetary-Mass companions could be gravitationally bound to the targets. This region was left largely unstudied by past high-contrast imaging surveys, which probed much closer-in separations. This survey led to the discovery of a Planetary-Mass (9-13 $\,M_{\rm{Jup}}$) companion at 2000 au from the M3V star GU Psc, a highly probable member of ABDMG. No other substellar companions were identified. These results allowed us to constrain the frequency of distant Planetary-Mass companions (5-13 $\,M_{\rm{Jup}}$) to 0.84$_{-0.66}^{+6.73}$% (95% confidence) at semimajor axes between 500 and 5000 au around young K5-L5 stars and brown dwarfs. This is consistent with other studies suggesting that gravitationally bound Planetary-Mass companions at wide separations from low-Mass stars are relatively rare.
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CFBDSIR 2149-0403: young isolated Planetary-Mass object or high-metallicity low-Mass brown dwarf?
Astronomy & Astrophysics, 2017Co-Authors: P. Delorme, Michael C. Liu, Trent J. Dupuy, Étienne Artigau, Jonathan Gagné, Loic Albert, C. Reylé, T. Forveille, X. Delfosse, F. AllardAbstract:Aims. We conducted a multi-wavelength, multi-instrument observational characterisation of the candidate free-floating planet CFBDSIR J214947.2−040308.9, a late T-dwarf with possible low-gravity features, in order to constrain its physical properties. Methods. We analysed nine hours of X-shooter spectroscopy with signal detectable from 0.8 to 2.3 μ m, as well as additional photometry in the mid-infrared using the Spitzer Space Telescope. Combined with a VLT/HAWK-I astrometric parallax, this enabled a full characterisation of the absolute flux from the visible to 5 μ m, encompassing more than 90% of the expected energy emitted by such a cool late T-type object. Our analysis of the spectrum also provided the radial velocity and therefore the determination of its full 3D kinematics. Results. While our new spectrum confirms the low gravity and/or high metallicity of CFBDSIR 2149, the parallax and kinematics safely rule out membership to any known young moving group, including AB Doradus. We use the equivalent width of the K i doublet at 1.25 μ m as a promising tool to discriminate the effects of low-gravity from the effects of high-metallicity on the emission spectra of cool atmospheres. In the case of CFBDSIR 2149, the observed K i doublet clearly favours the low-gravity solution. Conclusions. CFBDSIR 2149 is therefore a peculiar late-T dwarf that is probably a young, Planetary-Mass object (2–13 M Jup , M Jup brown dwarf with super-solar metallicity.
