On the circum(sub)stellar environment of brown dwarfs in Taurus

Guieu, S.; Pinte, C.; Monin, Jean‐Louis; Ménard, F.; Fukagawa, Misato; Padgett, Deborah; Noriega-Crespo, A.; Carey, Sean; Rebull, L. M.; Huard, Tracy L.; Guêdel, M.

doi:10.1051/0004-6361:20066140

Cited by 41 publications

(103 citation statements)

References 55 publications

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“…4.3). The lack of significant disk-contribution was also confirmed by Guieu et al (2007) from a full-SED analysis but required a higher extinction (A V = 2.45). The extinction was also re-evaluated by Kraus et al (2006) to A V = 4 based on the fit of the optical+NIR SED with redenned field dwarfs templates.…”

Section: Infrared Excesses and Extinctionsmentioning

confidence: 65%

“…The spectra of DH Tau B and CT Cha b were compared to low-resolution (R ∼ 100) templates of young (1-3 Myr), optically classified M5-M9 members of the Taurus and IC348 (Muench et al 2007) dereddened by their extinction values (Luhman 1999(Luhman , 2004Briceño et al 2002;Guieu et al 2007). We used in addition medium-resolution (R ∼ 2000) spectra of M5−M7 Taurus and ρ Ophiucus objects (Allers et al 2009;Rice et al 2010) and low-resolution (R ∼ 300-350) J band spectra of 1-3 Myr old objects obtained by Gorlova et al (2003).…”

Section: Comparison To Spectral Templatesmentioning

confidence: 99%

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A library of near-infrared integral field spectra of young M–L dwarfs

Bonnefoy

Chauvin

Lagrange

et al. 2014

A&A

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144

204

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Context. At young ages, low surface gravity affects the atmospheric properties of ultracool dwarfs. The impact on medium-resolution near-infrared (NIR) spectra has only been slightly investigated at the M-L transition so far. Aims. We present a library of NIR (1.1-2.45 µm) medium-resolution (R ∼ 1500-2000) integral field spectra of 15 young M6−L0 dwarfs. We aim at deriving updated NIR spectral type, luminosity, and physical parameters (T eff , log g, M, L/L ) for each source. This work also aims at testing the latest generation of BT-SETTL atmospheric models. Methods. We estimated spectral types using spectral indices and the spectra of young objects classified in the optical. We used the 2010 and 2012 releases of the BT-SETTL synthetic spectral grid and cross-checked the results with the DRIFT-PHOENIX models to derive the atmospheric properties of the sources. Results. We do not find significant differences between the spectra of young companions and those of young isolated brown dwarfs in the same spectral type range. We derive infrared spectral types L0 ± 1, L0 ± 1, M9.5 ± 0.5, M9.5 ± 0.5, M9.25 ± 0.25, M8 +0.5 −0.75 , and M8.5 ± 0.5 for AB Pic b, Cha J110913-773444, USco CTIO 108B, GSC 08047-00232 B, DH Tau B, CT Cha b, and HR7329B, respectively. The BT-SETTL and DRIFT-PHOENIX models yield close T eff and log g estimates for each source. The models seem to show a 600 +600 −300 K drop in the effective temperature at the M-L transition. Assuming the former temperatures are correct, we then derive new mass estimates that confirm that DH Tau B, USco CTIO 108B, AB Pic b, KPNO Tau 4, OTS 44, and Cha1109 lie inside or at the boundary of the planetary mass range. We combine the empirical luminosities of the M9.5-L0 sources to the T eff to derive semi-empirical radii estimates that do not match "hot-start" evolutionary models predictions at 1-3 Myr. We use complementary data to demonstrate that atmospheric models are able to reproduce the combined optical and infrared spectral energy distribution, together with the NIR spectra of these sources simultaneously. But the models still fail to represent the dominant features in the optical. This issue raises doubts on the ability of these models to predict effective temperatures from NIR spectra alone. Conclusions. The library provides templates for characterizing other young and late type objects. The study advocates the use of photometric and spectroscopic information over a broad range of wavelengths to study the properties of very low-mass young companions to be detected with the planet imagers (Subaru/SCExAO, LBT/LMIRCam, Gemini/GPI, VLT/SPHERE).

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Section: Infrared Excesses and Extinctionsmentioning

confidence: 65%

Section: Comparison To Spectral Templatesmentioning

confidence: 99%

A library of near-infrared integral field spectra of young M–L dwarfs

Bonnefoy

Chauvin

Lagrange

et al. 2014

A&A

Self Cite

144

204

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show abstract

“…The original measurements were in the R C and I C filters for those targets reported in Kenyon & Hartmann (1995), whilst all other compiled literature studies transformed the measured photometric value into the Cousins system (Guieu et al 2007(Guieu et al , 2006Luhman 2000Luhman , 2004Luhman et al 2003a;Briceño et al 1999Briceño et al , 2002Martín et al 2001). For targets with more than one photometric measurement, the median value was adopted.…”

Section: Construction Of Spectral Energy Distributionsmentioning

confidence: 99%

“…Infrared and mid-infrared observations of young brown dwarfs (e.g., Luhman 2006;Luhman et al 2010;Guieu et al 2007) have enabled the identification of inner disks. This common presence of disks around stellar and substellar objects has been used to argue for a common formation mechanism (Scholz & Jayawardhana 2008;Haisch et al 2010), while other observations hint at possible differences in the dynamical history of low mass stars/brown dwarfs compared to higher mass stars (Thies & Kroupa 2007).…”

Section: Introductionmentioning

confidence: 99%

The Taurus Boundary of Stellar/Substellar (TBOSS) Survey

Bulger

Patience

Ward-Duong

et al. 2014

A&A

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With the PACS instrument on Herschel, 134 low mass members of the Taurus star-forming region spanning the M4-L0 spectral type range and covering the transition from low mass stars to brown dwarfs were observed. Combining the new Herschel results with other Herschel programs, a total of 150 of the 154 M4-L0 Taurus members have observations, and we have added an additional 3 targets from Spitzer to form the 153-object TBOSS (Taurus Boundary of Stellar/Substellar) sample, a 99% complete study. Among the 150 targets, 70 µm flux densities were measured for 7 of the 7 Class I objects, 48 of the 67 Class II objects, and 3 of the 76 Class III objects. For the detected Class II objects, the median 70 µm flux density level declines with spectral type; however, the distribution of excess relative to central object flux density does not change across the stellar/substellar boundary in the M4-L0 range. Connecting the 70 µm TBOSS values with the results from K0-M3 Class II members results in the first comprehensive census of far-IR emission across the full mass spectrum of the stellar and substellar population of a star-forming region, and the median flux density declines with spectral type in a trend analogous to the flux density decline expected for the central objects. Spectral energy distributions (SEDs) were constructed for all TBOSS targets covering the optical to far-IR range and extending to the submm/mm for a subset of sources with longer wavelength data. Based on an initial exploration of the impact of different physical parameters on the Herschel flux densities, geometrical factors such as inclination and structural parameters such as scale height and flaring have the largest influence on the flux densities in the PACS bands. From the 24 µm to 70 µm spectral index of the SEDs, 5 new candidate transition disks were identified. Considering the previously known and new candidate transition disks, the spectral indices over longer wavelengths (≥70 µm) are not distinct from those of the full Class II population, suggesting that the outer regions of the transition disks are similar to Class II disks. The steep 24 µm to 70 µm slope for a subset of 8 TBOSS targets may be an indication of truncated disks in these systems, however additional measurements are required to establish the outer radii of these disks conclusively. From existing high angular resolution companion search observations, two examples of mixed pair systems that include secondaries with disks were measured in the Herschel data. Finally, comparing the TBOSS results with a Herschel study of Ophiuchus brown dwarfs reveals a lower fraction of disks around the Taurus substellar population with flux densities comparable to the Ophiuchus disks.

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“…These objects (as well as KPNO-Tau 12) have strong Hα emission, indicating the presence of an accretion disc (Muzerolle et al 2005). In addition, KPNO-Tau 6 and KPNO-Tau 7 have significant mid-IR excesses in the Spitzer/IRAC passbands (Guieu et al 2007). The youth of these objects is unquestioned.…”

Section: Extending the Datasetmentioning

confidence: 99%

Towards precise ages and masses of Free Floating Planetary Mass Brown Dwarfs

Canty¹,

Lucas²,

Roche³

et al. 2013

Monthly Notices of the Royal Astronomical Society

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Measurement of the substellar initial mass function (IMF) in very young clusters is hampered by the possibility of the age spread of cluster members. This is particularly serious for candidate planetary mass objects (PMOs), which have a very similar location to older and more massive brown dwarfs on the Hertzsprung-Russell Diagram (HRD). This degeneracy can be lifted by the measurement of gravity sensitive spectral features. To this end we have obtained medium resolution (R≈5000) Near-infrared Integral Field Spectrometer (NIFS) K band spectra of a sample of late M-/early L-type dwarfs. The sample comprises old field dwarfs and very young brown dwarfs in the Taurus association and in the σ Orionis cluster. We demonstrate a positive correlation between the strengths of the 2.21 µm NaI doublet and the objects' ages. We demonstrate a further correlation between these objects' ages and the shape of their K band spectra. We have quantified this correlation in the form of a new index, the H 2 (K) index. This index appears to be more gravity-sensitive than the NaI doublet and has the advantage that it can be computed for spectra where gravity-sensitive spectral lines are unresolved, while it is also more sensitive to surface gravity at very young ages (<10 Myr) than the triangular H band peak. Both correlations differentiate young objects from field dwarfs, while the H 2 (K) index can distinguish, at least statistically, populations of ∼1 Myr objects from populations of ∼10 Myr objects. We applied the H 2 (K) index to NIFS data for one Orion nebula cluster (ONC) PMO and to previously published low resolution spectra for several other ONC PMOs where the 2.21 µm NaI doublet was unresolved and concluded that the average age of the PMOs is ∼1 Myr.

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On the circum(sub)stellar environment of brown dwarfs in Taurus

Cited by 41 publications

References 55 publications

A library of near-infrared integral field spectra of young M–L dwarfs

A library of near-infrared integral field spectra of young M–L dwarfs

The Taurus Boundary of Stellar/Substellar (TBOSS) Survey

Towards precise ages and masses of Free Floating Planetary Mass Brown Dwarfs

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