DEEP NEAR-INFRARED IMAGING OF THE {rho} Oph CLOUD CORE: CLUES TO THE ORIGIN OF THE LOWEST-MASS BROWN DWARFS

Journal Article · Tue Aug 10 00:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/719/1/550· OSTI ID:21455000

Marsh, Kenneth A; Plavchan, Peter; Kirkpatrick, J Davy; Lowrance, Patrick J; Cutri, Roc M ^[1]; Velusamy, Thangasamy ^[2]

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1. Infrared Processing and Analysis Center, California Institute of Technology 100-22, Pasadena, CA 91125 (United States)
2. Jet Propulsion Laboratory, MS 169-506, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

A search for young substellar objects in the {rho} Oph cloud core region has been made with the aid of multiband profile-fitting point-source photometry of the deep-integration Combined Calibration Scan images of the 2MASS extended mission in the J, H, and K{sub s} bands, and Spitzer IRAC images at 3.6, 4.5, 5.8, and 8.0 {mu}m. The field of view of the combined observations was 1{sup 0} x 9.'3, and the 5{sigma} limiting magnitude at J was 20.5. Comparison of the observed spectral energy distributions with the predictions of the COND and DUSTY models, for an assumed age of 1 Myr, supports the identification of many of the sources with brown dwarfs and enables the estimation of effective temperature, T {sub eff}. The cluster members are then readily distinguishable from background stars by their locations on a plot of flux density versus T {sub eff}. The range of estimated T {sub eff} values extends down to {approx}750 K which, based on the COND model, would suggest the presence of objects of sub-Jupiter mass. The results also suggest that the mass function for the {rho} Oph cloud resembles that of the {sigma} Orionis cluster based on a recent study, with both rising steadily toward lower masses. The other main result from our study is the apparent presence of a progressive blueward skew in the distribution of J - H and H - K{sub s} colors, such that the blue end of the range becomes increasingly bluer with increasing magnitude. We suggest that this behavior might be understood in terms of the 'ejected stellar embryo' hypothesis, whereby some of the lowest-mass brown dwarfs could escape to locations close to the front edge of the cloud, and thereby be seen with less extinction.

• OSTI ID: 21455000
• Journal Information: Astrophysical Journal, Vol. 719, Issue 1; Other Information: DOI: 10.1088/0004-637X/719/1/550; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ENERGY SPECTRA
FLUX DENSITY
JUPITER PLANET
POINT SOURCES
STARS
PLANETS
RADIATION SOURCES
SPECTRA