HD 203030B: An Unusually Cool Young Substellar Companion near the L/T Transition

Metchev, Stanimir; Hillenbrand, Lynne A.

doi:10.1086/507836

Cited by 183 publications

(177 citation statements)

References 79 publications

(132 reference statements)

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“…3 the IFS spectra of HR8799 d and e to the ones of the aforementioned red dwarfs and companions. We considered as well a comparison to the spectra of the companions HD 203030B (age ∼ 0.13−0.4 Gyr, Metchev & Hillenbrand 2006;Rojo et al 2015, in prep. ) and 2M1207b (8 Myr, Patience et al 2010).…”

Section: Spectra and Sedsmentioning

confidence: 99%

First light of the VLT planet finder SPHERE

Bonnefoy¹,

Zurlo²,

Baudino³

et al. 2016

A&A

130

104

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Context. The system of four planets discovered around the intermediate-mass star HR8799 offers a unique opportunity to test planet formation theories at large orbital radii and to probe the physics and chemistry at play in the atmospheres of self-luminous young (∼30 Myr) planets. We recently obtained new photometry of the four planets and low-resolution (R ∼ 30) spectra of HR8799 d and e with the SPHERE instrument (Paper III). Aims. In this paper (Paper IV), we aim to use these spectra and available photometry to determine how they compare to known objects, what the planet physical properties are, and how their atmospheres work. Methods. We compare the available spectra, photometry, and spectral energy distribution (SED) of the planets to field dwarfs and young companions. In addition, we use the extinction from corundum, silicate (enstatite and forsterite), or iron grains likely to form in the atmosphere of the planets to try to better understand empirically the peculiarity of their spectrophotometric properties. To conclude, we use three sets of atmospheric models (BT-SETTL14, Cloud-AE60, Exo-REM) to determine which ingredients are critically needed in the models to represent the SED of the objects, and to constrain their atmospheric parameters (T eff , log g, M/H). Results. We find that HR8799d and e properties are well reproduced by those of L6-L8 dusty dwarfs discovered in the field, among which some are candidate members of young nearby associations. No known object reproduces well the properties of planets b and c. Nevertheless, we find that the spectra and WISE photometry of peculiar and/or young early-T dwarfs reddened by submicron grains made of corundum, iron, enstatite, or forsterite successfully reproduce the SED of these planets. Our analysis confirms that only the Exo-REM models with thick clouds fit (within 2σ) the whole set of spectrophotometric datapoints available for HR8799 d and e for T eff = 1200 K, log g in the range 3.0−4.5, and M/H = +0.5. The models still fail to reproduce the SED of HR8799c and b. The determination of the metallicity, log g, and cloud thickness are degenerate. Conclusions. Our empirical analysis and atmospheric modelling show that an enhanced content in dust and decreased CIA of H 2 is certainly responsible for the deviation of the properties of the planet with respect to field dwarfs. The analysis suggests in addition that HR8799c and b have later spectral types than the two other planets, and therefore could both have lower masses.

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Section: Spectra and Sedsmentioning

confidence: 99%

First light of the VLT planet finder SPHERE

Bonnefoy¹,

Zurlo²,

Baudino³

et al. 2016

A&A

130

104

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“…The L and T dwarf spectra studied herein cover a broad range of wavelengths, while most published spectra cover only the red optical and near-infrared wavelengths (e.g., Cruz et al 2003;Knapp et al 2004) or even a single photometric band (e.g., Neuhäuser et al 2005;Metchev & Hillenbrand 2006). It is therefore appropriate to investigate how well the atmospheric parameters of L and T dwarfs can be determined by fitting L and T dwarf spectra over narrower wavelength ranges.…”

Section: Fits To Individual Photometric Bandsmentioning

confidence: 99%

Atmospheric Parameters of Field L and T Dwarfs1

Cushing

Marley

Saumon

et al. 2008

ApJ

313

448

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We present an analysis of the 0.95Y14.5 m spectral energy distributions of nine field ultracool dwarfs with spectral types ranging from L1 to T4.5. Effective temperatures, gravities, and condensate cloud sedimentation efficiencies are derived by comparing the data to synthetic spectra computed from atmospheric models that self-consistently include the formation of condensate clouds. Overall, the model spectra fit the data well, although the agreement at some wavelengths remains poor due to remaining inadequacies in the models. Derived effective temperatures decrease steadily through the L1YT4.5 spectral types, and we confirm that the effective temperatures of ultracool dwarfs at the L/T transition are nearly constant, decreasing by only $200 K from spectral types L7.5 to T4.5. The condensate cloud properties vary significantly among the L dwarfs in our sample, ranging from very thick clouds to relatively thin clouds with no particular trend with spectral type. The two objects in our sample with very red J À K s colors are, however, best fitted with synthetic spectra that have thick clouds, which hints at a possible correlation between the near-infrared colors of L dwarfs and the condensate cloud properties. The fits to the two T dwarfs in our sample (T2 and T4.5) also suggest that the clouds become thinner in this spectral class, in agreement with previous studies. Restricting the fits to narrower wavelength ranges (i.e., individual photometric bands) almost always yields excellent agreement between the data and models. Limitations in our knowledge of the opacities of key absorbers such as FeH, VO, and CH 4 at certain wavelengths remain obvious, however. The effective temperatures obtained by fitting the narrower wavelength ranges can show a large scatter compared to the values derived by fitting the full spectral energy distributions; deviations are typically $200 K and, in the worst cases, up to 700 K.

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“…For example, Metchev & Hillenbrand (2005) targeted 100 F5YK5 primaries to look for brown dwarf companions. Based on a single detection, they derive a substellar companion frequency of at least 1%, and possibly on the order of a few percent.…”

Section: Frequency Of Ultraylow-mass Companionsmentioning

confidence: 99%

Multiplicity among Young Brown Dwarfs and Very Low Mass Stars

Ahmic

Jayawardhana

Brandeker

et al. 2007

ApJ

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We report on a near-infrared adaptive optics imaging survey of 31 young brown dwarfs and very low mass ( VLM) stars, 28 of which are in the Chamaeleon I star-forming region, using the ESO Very Large Telescope. We resolve the suspected 0:16 00 ($26 AU ) binary Cha H 2 and present two new binaries, Hn 13 and CHXR 15, with separations of 0:13 00 ($20 AU ) and 0:30 00 ($50 AU ), respectively; the latter is one of the widest VLM systems known. We find a binary frequency of 11 þ9 À6 %, thus confirming the trend for a lower binary frequency with decreasing mass. By combining our work with previous surveys, we arrive at the largest sample of young VLM objects (72) with high angular resolution imaging to date. Its multiplicity fraction is in statistical agreement with that for VLM objects in the field. Furthermore, we note that many field stellar binaries with lower binding energies and/or wider cross sections have survived dynamical evolution and that statistical models suggest tidal disruption by passing stars is unlikely to affect the binary properties of our systems. Thus, we argue that there is no significant evolution of multiplicity with age among brown dwarfs and VLM stars in OB and T associations between a few megayears to several gigayears. Instead, the observations so far suggest that VLM objects are either less likely to be born in fragile multiple systems than solarmass stars or such systems are disrupted very early.

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HD 203030B: An Unusually Cool Young Substellar Companion near the L/T Transition

Cited by 183 publications

References 79 publications

First light of the VLT planet finder SPHERE

First light of the VLT planet finder SPHERE

Atmospheric Parameters of Field L and T Dwarfs1

Multiplicity among Young Brown Dwarfs and Very Low Mass Stars

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