The Nature of Transition Circumstellar Disks II.Southern Molecular Clouds

GISELA A. ROMERO, MATTHIAS R. SCHREIBER, LUCAS A. CIEZA, ALBERTO REBASSA-MANSERGAS, BRUNO MERÍN, ANALÍA V. SMITH CASTELLI, LORI E. ALLEN, AND NIDIA MORRELL

ASTROPHYSICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2012 vol. 749 p. 79 - 97

0004-637X

Transition disk objects are pre-main-sequence stars with little or no near-IR excess and significant far-IR excess, implying inner opacity holes in their disks. Here we present a multifrequency study of transition disk candidates located in Lupus I, III, IV, V, VI, Corona Australis, and Scorpius. Complementing the information providedby Spitzer with Adaptive Optics (AO) imaging (NaCo, VLT),  submillimeter photometry (APEX), and echelle spectroscopy (Magellan, Du Pont Telescopes), we estimate the multiplicity, disk mass, and accretion rate for each object in our sample in order toidentify the mechanism potentially responsible for its inner hole. We find that our transition disks show a rich diversity in their SED morphology, have disk masses ranging from < 1 to 10 M_JUP and accretion rates ranging from < 10-11 to 10-7.7 M yr^{-1} . Of the 17 bona fide transition disks in our sample, 3, 9, 3, and 2 objects are consistent with giant planet formation, grain growth,  photoevaporation, and debris disks, respectively. Two disks could be circumbinary, which offers tidal truncation as an alternative originof the inner hole. We find the same heterogeneity of the transition disk population in Lupus III, IV, and Corona Australis as in our previous analysis of transition disks in Ophiuchus while all transition disk candidates selected in Lupus V, VI turned out to be  contaminating background AGB stars. All transition disks classified as photoevaporating disks have small disk masses, which indicates that photoevaporation must be less efficient than predicted by most recent models. The three systems that are excellent candidates for harboring giant planets potentially represent invaluable laboratories to study planet formation with ALMA.