Detection of Disk Accretion at the Substellar Limit

Muzerolle, James; Calvet, Nuria; Hartmann, L.; Hillenbrand, Lynne A.; Gullbring, E.

doi:10.1086/317877

Cited by 68 publications

(88 citation statements)

References 21 publications

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“…In addition, Hartigan et al (1995) found that objects with higher mass accretion rates tend to have higher mass outflow rates (see also Cabrit & André 1991;Cabrit & Bertout 1992). Muzerolle et al (2000) derived a mass accretion rate of ∼5×10 −12 M yr −1 for V410 Anon, a brown dwarf in the Taurus cloud. As these authors note, this mass accretion rate is at least three orders of magnitude lower than that typically corresponding to a 0.5 M star ).…”

Section: Discussionmentioning

confidence: 98%

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A search for shock-excited molecular hydrogen knots in Chamaeleon I very low mass YSOs

Gómez¹,

Persi

Marenzi

et al. 2004

A&A

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Abstract.We have obtained narrow-band images of three selected areas of the Chamaeleon I dark cloud which harbor very low mass young stars, centered on the H 2 and Brγ lines and neighboring continuum as well as on the broad band K s . One region is located in the northern part of the cloud, roughly coinciding with the densest area. The other two regions are in the southern section of the cloud. Our aim is to search for H 2 outflows associated with these objects. In the northern region, we found seven new H 2 knots, five of which are aligned in the direction of a previously known 12 CO molecular bipolar outflow. Further evidence that the class I low mass stellar object ISO-ChaI 192 is the driving source of the molecular flow is given by the presence of a 960 AU long elongated structure at 2.2 µm emanating from this star and oriented parallel to the bipolar structure. Another pair of H 2 knots, although lying relatively nearby, is not aligned with the outflow direction. They are located on opposite sides of C1-6, a low mass class II object in the northern part of the Chamaeleon I dark cloud. In contrast, we fail to detect any H 2 emission object brighter than our sensitivity limit (∼6 × 10 −32 W/m 2 Hz arcsec 2 ) in the two southern areas of the cloud that also harbor several very low mass stars, including two transition stellar/sub-stellar objects. This negative result is probably not surprising in view of the extremely low accretion rates measured for brown dwarfs (Ṁ ∼ 10 −12 −10 −9 M yr −1 ). Deeper H 2 observations are required to better constraint the outflow event in sub-stellar objects.

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Section: Discussionmentioning

confidence: 98%

“…Brown dwarfs (i.e., sub-stellar mass objects) may form in a similar manner as low mass stars surrounded by circumstellar disks (Muzerolle et al 2000;Natta & Testi 2001;Muench et al 2001;Jayawardhana et al 2003;Liu et al 2003). The standard star-like formation mode, however, involves the presence of outflows.…”

Section: Introductionmentioning

confidence: 99%

A search for shock-excited molecular hydrogen knots in Chamaeleon I very low mass YSOs

Gómez¹,

Persi

Marenzi

et al. 2004

A&A

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“…The considerable theoretical effort devoted to modeling the spectrum of accreting stars has understandably focused on young stellar objects with masses of a few tenths of a solar mass (Hartmann 1998), which is the range occupied by the vast majority of CTTS observed in detail so far. However, signposts of moderate mass accretion have been detected recently in very low mass stars and even young brown dwarfs (Luhman et al 1997;Comerón et al 2000;Muzerolle et al 2000), whose masses are in the range of hundredths of a solar mass. H α emission in very young objects with masses as low as ∼0.01 M , or perhaps even less, has been very recently reported by Zapatero-Osorio et al (2000) in the σ Orionis cluster.…”

Section: Introductionmentioning

confidence: 99%

Intense accretion and mass loss of a very low mass young stellar object

Fernández

Comerón²

2001

A&A

126

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Abstract. We present visible and near-infrared photometry and spectroscopy of LS-RCrA 1, a faint, very late-type object (M 6.5-M 7) seen in the direction of the R Coronae Australis star forming complex. While its emission spectrum shows prominent features of accretion and mass loss typical of young stellar objects, its underlying continuum and photometric properties are puzzling when trying to derive a mass and age based on pre-main sequence evolutionary tracks: the object appears to be far too faint for a young member of the R Coronae Australis complex of its spectral type. We speculate that this may be due to either its evolution along pre-main sequence tracks being substantially altered by the intense accretion, or to a combination of partial blocking and scattering of the light of the object by a nearly edge-on circumstellar disk. The rich emission line spectrum superimposed on the stellar continuum is well explained by an intense accretion process: the Hα, CaII infrared triplet, and HeI 6678 lines show equivalent widths typical of very active classical T Tauri stars. The near-infrared observations show anomalously weak spectral features and no significant excess emission in the K band, which we tentatively interpret as indicating line filling due to emission in a magnetic accretion funnel flow. At the same time, numerous, strong forbidden optical lines ([OI], [NII] and [SII]) and H2 emission at 2.12 µm suggest that the object is simultaneously undergoing mass loss, providing another example that shows that mass loss and accretion are closely related processes. Such an intense accretion and mass loss activity is observed for the first time in a young stellar object in the transition region between low mass stars and brown dwarfs, and provides a valuable observational test on the effects of accretion on the evolution of objects with such low masses.

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“…We can detect line emission from atoms and molecules of heavy elements, or from the warm surface layers of the disk, but the most common means of observing gas in disks is through signatures of accretion onto the stellar surface. Typically we detect either the accretion luminosity, observed as UV continuum emission or veiling of photospheric lines, or broad emission lines (such as Hα) that originate in the hot accretion flow (Hartigan et al, 1995;Gullbring et al, 1998;Muzerolle et al, 2000). There is a near one-to-one correspondence between solar-mass objects showing accretion signatures (usually referred to as classical T Tauri stars, henceforth CTTs) and those showing the IR excess characteristic of inner dust disks (IR Class II).…”

Section: Evolution Of Protoplanetary Disksmentioning

confidence: 99%

“…Disks have been found to cover a mass range of ∼ 0.1 − 0.001 M (Andrews and Williams, 2005), and to possess accretion rates of ∼ 10 −7 − 10 −10 M yr −1 (Hartigan et al, 1995;Gullbring et al, 1998;Muzerolle et al, 2000). The relative lack of objects seen between the disk-bearing Class II and disk-less Class III states implies that the dust clearing time scale is short (∼ 10 5 yr), and recent observations suggest that this twotime-scale constraint applies to the gaseous component of the disk also (Ingleby et al, 2009).…”

Section: Evolution Of Protoplanetary Disksmentioning

confidence: 99%

Circumstellar disks and planets

Wolf

Malbet

Alexander

et al. 2012

Astron Astrophys Rev

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We present a review of the interplay between the evolution of circumstellar disks and the formation of planets, both from the perspective of theoretical models and dedicated observations. Based on this, we identify and discuss fundamental questions concerning the formation and evolution of circumstellar disks and planets which can be addressed in the near future with optical and infrared long-baseline interferometers. Furthermore, the importance of complementary observations with long-baseline (sub)millimeter interferometers and high-sensitivity infrared observatories is outlined.

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Detection of Disk Accretion at the Substellar Limit

Cited by 68 publications

References 21 publications

A search for shock-excited molecular hydrogen knots in Chamaeleon I very low mass YSOs

A search for shock-excited molecular hydrogen knots in Chamaeleon I very low mass YSOs

Intense accretion and mass loss of a very low mass young stellar object

Circumstellar disks and planets

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