Alma observations of circumstellar disks in the upper scorpius OB Association

Journal Article · Sat Aug 20 04:00:00 EDT 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/827/2/142· OSTI ID:22868760

Barenfeld, Scott A. ^[1]; Carpenter, John M. ^[2]; Ricci, Luca ^[3]; Isella, Andrea ^[4]

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1. California Institute of Technology, Department of Astronomy, MC 249-17, Pasadena, CA 91125 (United States)
2. Joint ALMA Observatory, Av. Alonso de Córdova 3107, Vitacura, Santiago (Chile)
3. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
4. Department of Physics and Astronomy, Rice University, 6100 Main Street Houston, TX 77005 (United States)

We present ALMA observations of 106 G-, K-, and M-type stars in the Upper Scorpius OB Association hosting circumstellar disks. With these data, we measure the 0.88 mm continuum and {sup 12}CO J = 3–2 line fluxes of disks around low-mass (0.14–1.66 M {sub ⊙}) stars at an age of 5–11 Myr. Of the 75 primordial disks in the sample, 53 are detected in the dust continuum and 26 in CO. Of the 31 disks classified as debris/evolved transitional disks, five are detected in the continuum and none in CO. The lack of CO emission in approximately half of the disks with detected continuum emission can be explained if CO is optically thick but has a compact emitting area (≲40 au), or if the CO is heavily depleted by a factor of at least ∼1000 relative to interstellar medium abundances and is optically thin. The continuum measurements are used to estimate the dust mass of the disks. We find a correlation between disk dust mass and stellar host mass consistent with a power-law relation of M{sub dust}∝M{sub ∗}{sup 1.67±0.37}. Disk dust masses in Upper Sco are compared to those measured in the younger Taurus star-forming region to constrain the evolution of disk dust mass. We find that the difference in the mean of log(M{sub dust}/M{sub ∗}) between Taurus and Upper Sco is 0.64 ± 0.09, such that M {sub dust}/M {sub *} is lower in Upper Sco by a factor of ∼4.5.

• OSTI ID: 22868760
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 827; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
CARBON MONOXIDE
COMPARATIVE EVALUATIONS
CORRELATIONS
COSMIC DUST
EMISSION
MAIN SEQUENCE STARS
MASS
PROTOPLANETS