A Deep Near‐Infrared Survey of the Chamaeleon I Dark Cloud Core

Oasa, Yumiko; Tamura, Motohide; Sugitani, Koji

doi:10.1086/307964

Cited by 94 publications

(83 citation statements)

References 35 publications

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“…These sources are thus good new candidate young brown dwarfs of the cloud. The presence of other young sub-stellar members in the Cha I dark cloud have recently been shown by Neuhäuser & Comerón (1999), Oasa et al (1999), and Persi et al (2000).…”

Section: Stellar Luminositiesmentioning

confidence: 86%

Sub-arcsec resolution near-infrared images of the Cederblad 110 region

Persi

Marenzi

Gómez

et al. 2001

A&A

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Abstract. We present the results of deep (Ks = 18.9) sub-arcsec resolution (0.3 ) imaging observations of the Cederblad 110 region in the Chamaeleon I dark cloud. This region (roughly 5 × 5 ) is characterized by the presence of six ISOCAM-detected young stellar objects (YSOs). Our images have recovered all these sources at near-infrared (near-IR) wavelengths. Ced 110 IRS4, the brightest object in the region, is associated with a remarkable near-IR bipolar nebulosity. Ced 110 IRS6 is resolved in a double system IRS6a and IRS6b with a separation of ∼2 (∼320 AU at the distance of the Cha I cloud). We have combined 1.3 mm, far and mid-IR fluxes from the literature with our JHK data and obtained the spectral energy distributions (SEDs) for three (IRS4, IRS6a and ISO-ChaI86) of the six ISOCAM sources in the region. We modelled the SEDs of IRS6a and ISO-ChaI86 with a spherically symmetric dusty envelope, using the DUSTY code. These objects are clear Class I sources of the cloud. Finally, we report the detection of three new objects in this region (NIR 72, 84 and 89) with significant near-IR excess. If these sources are associated with the cloud, the derived luminosities and masses suggest that they are candidate young brown dwarfs of Chamaeleon I.

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Section: Stellar Luminositiesmentioning

confidence: 86%

Sub-arcsec resolution near-infrared images of the Cederblad 110 region

Persi

Marenzi

Gómez

et al. 2001

A&A

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“…This resolution is sufficient to study atomic and molecular lines. The age-sequence is composed of spectra of members of the Taurus (KPNO Tau 4; Briceño et al 2002), Chameleon I (OTS 44; Oasa et al 1999;Luhman et al 2004), and Upper Scorpius (UScoCTIO 108B; Béjar et al 2008) star forming regions. We also overlay the spectrum of the M10III Mira IO Virginis (Rayner et al 2009) as an example of an extremely low surface gravity atmospheres.…”

Section: An Age-sequence Of M95 Dwarfsmentioning

confidence: 99%

New constraints on the formation and settling of dust in the atmospheres of young M and L dwarfs

Manjavacas

Bonnefoy

Schlieder

et al. 2014

A&A

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Context. Gravity modifies the spectral features of young brown dwarfs (BDs). A proper characterization of these objects is crucial for the identification of the least massive and latest-type objects in star-forming regions, and to explain the origin(s) of the peculiar spectrophotometric properties of young directly imaged extrasolar planets and BD companions. Aims. We obtained medium-resolution (R ∼ 1500−1700) near-infrared (1.1−2.5 µm) spectra of seven young M9.5-L3 dwarfs classified at optical wavelengths. We aim to empirically confirm the low surface gravity of the objects in the near-infrared. We also test whether self-consistent atmospheric models correctly represent the formation and the settling of dust clouds in the atmosphere of young late-M and L dwarfs. Methods. We used the Infrared Spectrometer And Array Camera (ISAAC) at the Very Large Telescope (VLT) to obtain the spectra of the targets. We compared the spectra to those of mature and young BDs, and to young late-type companions to nearby stars with known ages to identify and study gravity-sensitive features. We computed spectral indices weakly sensitive to the surface gravity to derive near-infrared spectral types. Finally, we found the best fit between each spectrum and synthetic spectra from the BT-Settl 2010 and 2013 atmospheric models. Using the best fit, we derived the atmospheric parameters of the objects and identified which spectral characteristics the models do not reproduce. Results. We confirmed that our objects are young BDs and we found near-infrared spectral types in agreement with the ones determined at optical wavelengths. The spectrum of the L2γ dwarf 2MASSJ232252.99-615127.5 reproduces the spectrum of the planetary mass companion 1RXS J160929.1-210524b well. The BT-Settl models fit the spectra and the 1−5 µm spectral energy distribution of the L0-L3 dwarfs for temperatures between 1600−2000 K. But the models fail to reproduce the shape of the H band and the near-infrared slope of some of our targets. This fact, and the best-fit solutions found with super-solar metallicity, are indicative of a lack of dust, in particular at high altitude, in the cloud models. Conclusions. The modeling of the vertical mixing and of the grain growth will be revised in the next version of the BT-Settl models. These revisions may suppress the remaining non-reproducibilities. Our spectra provide additional templates for the characterization of the numerous young L-type companions that will be detected in the coming years by planet imaging instruments such as VLT/SPHERE, Gemini/GPI, Subaru/SCexAO, and LBTI/LMIRCam.

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“…Among these discoveries, planetary mass objects ( 13.6 M Jup , see the definition of the International Astronomical Union) were found to be free-floating (e.g. Oasa et al 1999;Lucas & Roche 2000;Zapatero Osorio et al 2000), orbiting brown dwarfs (2MASSW J1207334-393254, USCO CTIO 108, 2MASS J04414489+2301513; Chauvin et al 2004;Béjar et al 2008;Todorov et al 2010) or as wide (>5 AU) companions to stars (AB Pic, DH Tau, CHXR 73, GQ Lup, CT Cha, Fomalhaut, HR8799, β Pictoris, GSC 06214-00210, 1RXS J235133.3+312720, κ Andromedae; Chauvin et al 2005b;Itoh et al 2005;Luhman et al 2006;Neuhäuser et al 2005;Schmidt et al 2008;Kalas et al 2008;Marois et al 2008Marois et al , 2010Lagrange et al 2010;Ireland et al 2011;Bowler et al 2012;Carson et al 2013), or even binaries (SR 12 AB, 2MASS J01033563-5515561 AB; Kuzuhara et al 2011;Delorme et al 2013). This variety of configurations offers precious benchmarks for planet and brown-dwarf formation models (e.g.…”

Section: Introductionmentioning

confidence: 99%

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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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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A Deep Near‐Infrared Survey of the Chamaeleon I Dark Cloud Core

Cited by 94 publications

References 35 publications

Sub-arcsec resolution near-infrared images of the Cederblad 110 region

Sub-arcsec resolution near-infrared images of the Cederblad 110 region

New constraints on the formation and settling of dust in the atmospheres of young M and L dwarfs

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

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