CFBDSIR 2149-0403: young isolated planetary-mass object  or high-metallicity low-mass brown dwarf?

Delorme, P.; Dupuy, Trent J.; Gagné, Jonathan; Reylé, C.; Forveille, T.; Liu, Mengmeng; Artigau, Étienne; Li, Albert; Delfosse, X.; Allard, F.; Homeier, D.; Malo, Lison; Morley, Caroline; Naud, Marie-Ève; Bonnefoy, M.

doi:10.1051/0004-6361/201629633

Cited by 9 publications

(8 citation statements)

References 77 publications

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“…2, the spectral shape of the H and K bands clearly indicates a low gravity and/or high metallicity, a degeneracy already observed for other objects (e.g. Delorme et al 2017). Dedicated studies of the metallicity of moving groups point towards low values, e.g.…”

Section: Discussion and Jwst Perspectivessupporting

confidence: 58%

Cloudless Atmospheres for Young Low-gravity Substellar Objects

Tremblin

Chabrier

Baraffe

et al. 2017

ApJ

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Atmospheric modeling of low-gravity (VL-G) young brown dwarfs remains a challenge. The presence of very thick clouds has been suggested because of their extremely red near-infrared (NIR) spectra, but no cloud models provide a good fit to the data with a radius compatible with evolutionary models for these objects. We show that cloudless atmospheres assuming a temperature gradient reduction caused by fingering convection provides a very good model to match the observed VL-G NIR spectra. The sequence of extremely red colors in the NIR for atmospheres with effective temperature from ∼ 2000 K down to ∼ 1200 K is very well reproduced with predicted radii typical of young low-gravity objects. Future observations with NIRSPEC and MIRI on the James Webb Space Telescope (JWST) will provide more constrains in the mid-infrared, helping to confirm/refute whether or not the NIR reddening is caused by fingering convection. We suggest that the presence/absence of clouds will be directly determined by the silicate absorption features that can be observed with MIRI. JWST will therefore be able to better characterize the atmosphere of these hot young brown dwarfs and their low-gravity exoplanet analogues.

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Section: Discussion and Jwst Perspectivessupporting

confidence: 58%

Cloudless Atmospheres for Young Low-gravity Substellar Objects

Tremblin

Chabrier

Baraffe

et al. 2017

ApJ

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“…Three other late-T objects have similar deviant colors: WISEP J231336.41-803701.4 (Burgasser et al 2011), CFBD-SIR J214947.2-040308.9 (Delorme et al 2012), and 51 Eri b (Macintosh et al 2015). CFBDSIR2149-04 is possibly younger than the field and/or metal enriched (Delorme et al 2017a). The A63, page 7 of 32 A&A 618, A63 (2018)…”

Section: Empirical Analysis Of Gj 504b Photometrymentioning

confidence: 99%

“…Comparison of the final T eff and bolometric luminosity of GJ 504b (dashed zone) to those of late-T and early-Y dwarfs. The bolometric luminosity values are taken from Dupuy & Kraus (2013) and Delorme et al (2017a). The temperatures and luminosity of benchmark companions are taken from Table A.2.…”

Section: Mass Estimatesmentioning

confidence: 99%

The GJ 504 system revisited

Bonnefoy

Perraut

Lagrange

et al. 2018

A&A

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Context. The G-type star GJ504A is known to host a 3–35 MJup companion whose temperature, mass, and projected separation all contribute to making it a test case for planet formation theories and atmospheric models of giant planets and light brown dwarfs. Aims. We aim at revisiting the system age, architecture, and companion physical and chemical properties using new complementary interferometric, radial-velocity, and high-contrast imaging data. Methods. We used the CHARA interferometer to measure GJ504A’s angular diameter and obtained an estimation of its radius in combinationwith the HIPPARCOS parallax. The radius was compared to evolutionary tracks to infer a new independent age range for the system. We collected dual imaging data with IRDIS on VLT/SPHERE to sample the near-infrared (1.02–2.25 μm) spectral energy distribution (SED) of the companion. The SED was compared to five independent grids of atmospheric models (petitCODE,Exo-REM, BT-SETTL, Morley et al., and ATMO) to infer the atmospheric parameters of GJ 504b and evaluate model-to-model systematic errors. In addition, we used a specific model grid exploring the effect of different C/O ratios. Contrast limits from 2011 to 2017 were combined with radial velocity data of the host star through the MESS2 tool to define upper limits on the mass of additional companions in the system from 0.01 to 100 au. We used an MCMC fitting tool to constrain the companion’sorbital parameters based on the measured astrometry, and dedicated formation models to investigate its origin. Results. We report a radius of 1.35 ± 0.04 R⊙ for GJ504A. The radius yields isochronal ages of 21 ± 2 Myr or 4.0 ± 1.8 Gyr for the system and line-of-sight stellar rotation axis inclination of 162.4−4.3+3.8 degrees or 186.6−3.8+4.3 degrees. We re-detect the companion in the Y2, Y3, J3, H2, and K1 dual-band images. The complete 1–4 μm SED shape of GJ504b is best reproduced by T8-T9.5 objects with intermediate ages (≤ 1.5Gyr), and/or unusual dusty atmospheres and/or super-solar metallicities. All atmospheric models yield Teff = 550 ± 50 K for GJ504b and point toward a low surface gravity (3.5–4.0 dex). The accuracy on the metallicity value is limited by model-to-model systematics; it is not degenerate with the C/O ratio. We derive log L∕L⊙ = −6.15 ± 0.15 dex for the companion from the empirical analysis and spectral synthesis. The luminosity and Teff yield masses of M = 1.3−0.3+0.6 MJup and M = 23−9+10 MJup for the young and old age ranges, respectively. The semi-major axis (sma) is above 27.8 au and the eccentricity is lower than 0.55. The posterior on GJ 504b’s orbital inclination suggests a misalignment with the rotation axis of GJ 504A. We exclude additional objects (90% prob.) more massive than 2.5 and 30 MJup with semi-major axes in the range 0.01–80 au for the young and old isochronal ages, respectively. Conclusions. The mass and semi-major axis of GJ 504b are marginally compatible with a formation by disk-instability if the system is 4 Gyr old. The companion is in the envelope of the population of planets synthesized with our core-accretion model. Additional deep imaging and spectroscopic data with SPHERE and JWST should help to confirm the possible spin-orbit misalignment and refine the estimates on the companion temperature, luminosity, and atmospheric composition.

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“…At the resolution of our spectroscopic observations, gravity will affect mostly four features: J to K s continuum slope: A J − K s color redder than that of field brown dwarfs has been systematically reported for young brown dwarfs (e.g. Kirkpatrick et al 2008;Delorme et al 2017a) as well as for some young planets and brown dwarf companions to stars (e.g., Barman et al 2011;Delorme et al 2017b, and Fig. 1).…”

Section: Evidence Of Youthmentioning

confidence: 51%

Infrared spectroscopy of free-floating planet candidates in Upper Scorpius and Ophiuchus

Bouy

Tamura

Barrado

et al. 2022

A&A

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Context.A rich population of low-mass brown dwarfs and isolated planetary mass objects has been reported in the Upper Scorpius and Ophiuchus star-forming complex. Aims. We investigate the membership, nature, and properties of 17 of these isolated planetary mass candidates using low-resolution near-infrared spectra. Methods. We investigated the membership by looking for evidence of their youth using four diagnostics: the slope of the continuum between the J and Ks band, the H cont , and the TLI-g gravity-sensitive indices. In addition, we compared the spectra to young and field (old) M and L-dwarf standards. Results. All the targets but one are confirmed as young ultracool objects, with spectral types between L0 and L6 and masses in the range 0.004-0.013 M , according to evolutionary models. The status of the last target is unclear at this point. Conclusions. Only one possible contaminant has been identified among the 17 targets, suggesting that the contamination level of the original sample must be low ( 6%).

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CFBDSIR 2149-0403: young isolated planetary-mass object or high-metallicity low-mass brown dwarf?

Cited by 9 publications

References 77 publications

Cloudless Atmospheres for Young Low-gravity Substellar Objects

Cloudless Atmospheres for Young Low-gravity Substellar Objects

The GJ 504 system revisited

Infrared spectroscopy of free-floating planet candidates in Upper Scorpius and Ophiuchus

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