Extending the ALMA Census of Circumstellar Disks in the Upper Scorpius OB Association

Abstract We present Atacama Large Millimeter/submillimeter Array (ALMA) Band 7 continuum (340 GHz) and carbon monoxide (CO) J = 3–2 observations for an extended sample of disks in the Upper Scorpius OB Association (Upper Sco, age ∼10 Myr). The targets were selected from previous studies that identified new members of Upper Sco using photometry and astrometry from the Gaia mission, and the presence of a disk has been inferred from mid-infrared excess emission. The new ALMA observations are combined with previous ALMA data to define a sample of 202 Upper Sco members with disks that have spectral types between G0 and M5.5. Among these sources, 120 (59%) have been detected in the continuum with a signal-to-noise ratio ≥3, and 83 (41%) have been detected in CO J = 3–2. Both the continuum and CO J = 3–2 fluxes show a strong correlation with the spectral type of the central star and the type of disk inferred from the shape of the infrared spectral energy distribution, where disks around earlier-type stars and full disks are more luminous than disks around later-type stars and evolved and debris disks. The median dust continuum luminosity is lower for disks in Upper Sco than in younger regions, as found in previous studies, where the differences are more pronounced in later spectral types (M4–M5) than in earlier spectral types.