Four Brown Dwarfs in the Taurus Star-forming Region

Martín, E. L.; Dougados, C.; Magnier, E. A.; Ménard, F.; Magazzù, A.; Cuillandre, Jean-Charles; Delfosse, X.

doi:10.1086/324754

Cited by 113 publications

(121 citation statements)

References 24 publications

(36 reference statements)

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“…For example, Jayawardhana, Mohanty, & Basri (2002) have discovered a broad, asymmetric H line in GY5, indicative of ongoing accretion. Martín et al (2001) report emission in Br in CFHT-BDTau 4 as well as strong H . These observations extend into the BD range the well-known tendency for activity associated with youth observed in low-mass PMS stars.…”

Section: Other Effects At Young Agesmentioning

confidence: 89%

“…K i and Na i K i and Na i lines in the optical and near-infrared are known to be systematically weaker in cluster BDs compared to the same SpT in the field (Martín, Rebolo, & Zapatero Osorio 1996;Luhman et al 1998;Béjar, Zapatero Osorio, & Rebolo 1999;Lucas et al 2001;Martín et al 2001;Gizis 2002). However, no systematic study of the gravity dependence is available, particularly of the 1.25 lm feature of K i, which is conveniently situated near the middle of the J band.…”

Section: Sensitivity To Temperature and Gravitymentioning

confidence: 99%

“…However, in the absence of reliable SpTs, it is difficult to tell whether the effect was due to weakening of Na i and Ca i or to strengthening of CO with lower gravity in late-type stars. Thus, Martín et al (2001) had to invoke veiling from a circumstellar disk when they found that CO was actually weaker in the Taurus BDs compared to a field dwarf.…”

Section: Comentioning

confidence: 99%

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Gravity Indicators in the Near‐Infrared Spectra of Brown Dwarfs

Gorlova

Meyer

Rieke

et al. 2003

ApJ

149

183

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We investigate the sensitivity to temperature and gravity of the strong absorption features in the J-and K-band spectra of substellar objects. We compare the spectra of giants and young M dwarfs (of low gravity) to field M and L dwarfs (of high gravity) and to model spectra from the Lyon group. We find that low-resolution spectra of M4-M9 stars and young brown dwarfs at R $ 350 and signal-to-noise ratios greater than 70 can determine the spectral type to a precision of AE1 subtype using the H 2 O and CO bands and can measure the surface gravity to AE0.5 dex using the atomic lines of K i and Na i. This result points toward the development of photometric spectral indices to separate low-mass members from foreground and background objects in young clusters and associations. We also emphasize the complexity of the interpretation of the empirical quantities (e.g., spectral types) in terms of the physical variables (e.g., temperature, opacities) in the cool atmospheres of young brown dwarfs.

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Section: Other Effects At Young Agesmentioning

confidence: 89%

Section: Sensitivity To Temperature and Gravitymentioning

confidence: 99%

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Gravity Indicators in the Near‐Infrared Spectra of Brown Dwarfs

Gorlova

Meyer

Rieke

et al. 2003

ApJ

149

183

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“…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%

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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“…Subsequently, wide-field optical imaging has proven effective in uncovering members at substellar masses and across wide areas of the region (Briceño et al 1998;Martín et al 2001), particularly when combined with near-IR photometry from the Two Micron All Sky Survey (2MASS; Luhman 2000; Briceño et al 2002;Luhman et al 2003a). Additional brown dwarfs in Taurus have been identified through observations of the multiple system GG Tau (White et al 1999) and continuum sources (White & Basri 2003).…”

Section: Introductionmentioning

confidence: 99%

New Brown Dwarfs and an Updated Initial Mass Function in Taurus

Luhman

2004

ApJ

227

356

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By combining infrared photometry from the Two Micron All Sky Survey with new optical imaging and spectroscopy, I have performed a search for young low-mass stars and brown dwarfs in two regions encompassing a total area of 4 deg 2 in the Taurus star-forming region ( $ 1 Myr). From this work I have discovered 15 new members of Taurus. In addition, I present seven new members outside of these areas from the initial stage of a survey of all of Taurus. These 22 objects exhibit spectral types of M4.5-M9.25 and masses of 0.3-0.015 M according to the theoretical evolutionary models of Baraffe & Chabrier, seven of which are likely to be brown dwarfs. Emission in H , He i, Ca ii, [O i], and [S ii] and excess emission in optical and near-infrared bands among some of these objects suggest the presence of accretion, outflows, and circumstellar disks. These results add to the body of work-initiated by the first detections of brown dwarf disks by Comerón and coworkers in 1998 and Luhman in 1999-indicating that disks around young brown dwarfs are relatively common. The results from the 4 deg 2 survey have been combined with previous studies of Taurus to arrive at an initial mass function (IMF) for a total area of 12.4 deg 2 . As in the previous IMFs for Taurus, the updated IMF peaks at a higher mass (0.8 M ) than the mass functions in IC 348 and Orion (0.1-0.2 M ). Meanwhile, the deficit of brown dwarfs in Taurus appears to be less significant (;1:4 1:8) than that found in earlier studies (;2) because of a slightly higher brown dwarf fraction in the new IMF for Taurus and a lower brown dwarf fraction in the new spectroscopic IMF for the Trapezium from Slesnick and coworkers. The spatial distribution of the low-mass stars and brown dwarfs discovered in the two new survey areas closely matches that of the more massive members. Thus, on the degree size scales ($3 pc) probed to date, there is no indication that brown dwarfs form through ejection.

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Four Brown Dwarfs in the Taurus Star-forming Region

Cited by 113 publications

References 24 publications

Gravity Indicators in the Near‐Infrared Spectra of Brown Dwarfs

Gravity Indicators in the Near‐Infrared Spectra of Brown Dwarfs

The Taurus Boundary of Stellar/Substellar (TBOSS) Survey

New Brown Dwarfs and an Updated Initial Mass Function in Taurus

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