Spectroscopy of new brown dwarf members of<i>ρ</i> Ophiuchi and an updated initial mass function

Oliveira, Catarina Alves de; Moraux, E.; Bouvier, J.; Bouy, H.

doi:10.1051/0004-6361/201118230

Cited by 67 publications

(56 citation statements)

References 117 publications

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“…Previous mid-IR studies of ρ Ophiuchi have classified 31 brown dwarfs as Class II Natta et al 2002;Testi et al 2002;Barsony et al 2005;McClure et al 2010;Alves de Oliveira et al 2012). We detect 38% of the Class II brown dwarfs in our deep Herschel observations.…”

Section: Herschel/pacs Detectionssupporting

confidence: 51%

“…The existence of disks around several of these objects has been previously established from the detection of mid-IR excess (e.g. Bontemps et al 2001;Natta et al 2002;Testi et al 2002;Barsony et al 2005;McClure et al 2010;Alves de Oliveira et al 2012). The T Tauri disk population of this cluster has been studied by previous missions extending to the far-infrared regime (e.g.…”

Section: Introductionmentioning

confidence: 98%

“…At 1 Myr, the age usually taken for ρ Oph, the hydrogen-burning mass limit corresponds to a spectral type of ∼M6.25 (Luhman et al 2007; Baraffe et al 1998;Chabrier et al 2000). We focus our work on the most updated list of spectroscopically confirmed members with spectral type later than ∼M6 compiled in Alves de Oliveira et al (2012), adding to this list one brown dwarf found by Mužić et al (2012). There are 43 spectroscopically confirmed brown dwarf members of Ophiuchus.…”

Section: Introductionmentioning

confidence: 99%

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Herschelsurvey of brown dwarf disks inρOphiuchi

Oliveira

Ábrahám

Márton

et al. 2013

A&A

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Context. Young brown dwarfs are known to possess circumstellar disks, a characteristic that is fundamental to the understanding of their formation process, and raises the possibility that these objects harbour planets. Aims. We want to characterise the far-IR emission of disks around the young brown dwarf population of the ρ Ophiuchi cluster in LDN 1688. Methods. Recent observations of the ρ Ophiuchi cluster with the Herschel Space Observatory allow us to probe the spectral energy distribution (SED) of the brown dwarf population in the far-IR, where the disk emission peaks. We performed aperture photometry at 70, 100, and 160 µm, and constructed SEDs for all previously known brown dwarfs detected. These were complemented with ancillary photometry at shorter wavelengths. We compared the observed SEDs to a grid of synthetic disks produced with the radiative transfer code MCFOST, and used the relative figure of merit estimated from the Bayesian inference of each disk parameter to analyse the structural properties. Results. We detected 12 Class II brown dwarfs with Herschel, which corresponds to one-third of all currently known brown dwarf members of ρ Ophiuchi. We did not detect any of the known Class III brown dwarfs. Comparison to models reveals that the disks are best described by an inner radius between 0.01 and 0.07 AU, and a flared disk geometry with a flaring index between 1.05 and 1.2. Furthermore, we can exclude values of the disk scale-height lower than 10 AU (measured at a fiducial radius of 100 AU). We combined the Herschel data with recent ALMA observations of the brown dwarf GY92 204 (ISO−Oph 102), and by comparing its SED to the same grid of disk models, we derived an inner disk radius of 0.035 AU, a scale height of 15 AU with a flaring index of β ∼ 1.15, an exponent for dust settling of −1.5, and a disk mass of 0.001 M . This corresponds to a disk-to-central object mass ratio of ∼1%. Conclusions. The structural parameters constrained by the extended SED coverage (inner radius and flaring index) show a narrow distribution for the young brown dwarfs detected in ρ Ophiuchi, suggesting that these objects share the same disk evolution and, perhaps, formation.

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Section: Herschel/pacs Detectionssupporting

confidence: 51%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Herschelsurvey of brown dwarf disks inρOphiuchi

Oliveira

Ábrahám

Márton

et al. 2013

A&A

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“…Nowadays, more than 40 planetary mass companions have been detected using DI 1 . Most of them are found orbiting at large separations ( 50 AU) around young A&A 587, A58 (2016) and young nearby associations (Lucas et al 2001;Kirkpatrick et al 2006;Lodieu et al 2008;Rice et al 2010;Alves de Oliveira et al 2012Allers & Liu 2013;Gagné et al 2014a,b;Bonnefoy et al 2014a;Dawson et al 2014;Zapatero Osorio et al 2014). Among them, 2MASSW J1207334-393254 b (hereafter 2M1207b; Chauvin et al 2004), 2MASS J01225093-2439505 b (Bowler et al 2013), and VHS J125601.92-125723.9 b (Gauza et al 2015) appear to lie at the transition between the cloudy L-type and cloudless T-type dwarfs.…”

Section: Introductionmentioning

confidence: 99%

First light of the VLT planet finder SPHERE

Bonnefoy¹,

Zurlo²,

Baudino³

et al. 2016

A&A

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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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“…This is the goal of a large programme (P.I. J. Bouvier) we are conducting at the Canada-France-Hawaii Telescope (CFHT), designed to uncover the substellar population of various nearby young clusters and compare their IMF and minimum mass for brown dwarf formation (Burgess et al 2009;Alves de Oliveira et al 2010;Alves de Oliveira et al 2012;Spezzi et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Spectroscopy of brown dwarf candidates in IC 348 and the determination of its substellar IMF down to planetary masses

Oliveira

Moraux

Bouvier

et al. 2013

A&A

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Context. Brown dwarfs represent a sizable fraction of the stellar content of our Galaxy and populate the transition between the stellar and planetary mass regime. There is, however, no agreement on the processes responsible for their formation. Aims. We have conducted a large survey of the young, nearby cluster IC 348, to uncover its low-mass brown dwarf population and have studied the cluster properties in the substellar regime. Methods. Deep optical and near-IR images taken with MegaCam and WIRCam at the Canada-France-Hawaii Telescope (CFHT) were used to select photometric candidate members. A spectroscopic follow-up of a large fraction of the candidates was conducted to assess their youth and membership. Results. We confirmed spectroscopically 16 new members of the IC 348 cluster, including 13 brown dwarfs, contributing significantly to the substellar census of the cluster, where only 30 brown dwarfs were previously known. Five of the new members have a L0 spectral type, the latest-type objects found to date in this cluster. At 3 Myr, evolutionary models estimate these brown dwarfs to have a mass of ∼13 M Jup . Combining the new members with previous census of the cluster, we constructed the initial mass function (IMF) complete down to 13 M Jup . Conclusions. The IMF of IC 348 is well fitted by a log-normal function and we do not see evidence for variations of the mass function down to planetary masses when compared to other young clusters.

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Spectroscopy of new brown dwarf members ofρ Ophiuchi and an updated initial mass function

Cited by 67 publications

References 117 publications

Herschelsurvey of brown dwarf disks inρOphiuchi

Herschelsurvey of brown dwarf disks inρOphiuchi

First light of the VLT planet finder SPHERE

Spectroscopy of brown dwarf candidates in IC 348 and the determination of its substellar IMF down to planetary masses

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