THE SPITZER SURVEY OF INTERSTELLAR CLOUDS IN THE GOULD BELT. IV. LUPUS V AND VI OBSERVED WITH IRAC AND MIPS

Journal Article · Fri Apr 01 00:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/730/2/65· OSTI ID:21574613

Spezzi, Loredana; Vernazza, Pierre ^[1]; Merin, Bruno ^[2]; Allen, Lori E ^[3]; Evans, II, Neal J; Harvey, Paul M ^[4]; Joergensen, Jes K ^[5]; Bourke, Tyler L; Peterson, Dawn ^[6]; Cieza, Lucas A ^[7]; Dunham, Michael M ^[8]; Huard, Tracy L ^[9]; Tothill, Nick F. H. ^[10]

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1. Research and Scientific Support Department, ESTEC (ESA), Keplerlaan, 1, P.O. Box 299, 2200 AG Noordwijk (Netherlands)
2. Herschel Science Centre, ESAC (ESA), P.O. Box 78, 28691 Villanueva de la Canada, Madrid (Spain)
3. Department of Astronomy, University of Arizona, 933 N Cherry Ave., Tucson, AZ 85721-0065 (United States)
4. Department of Astronomy, University of Texas at Austin, 1 University Station, C1400 Austin, TX 78712-0259 (United States)
5. Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Oester Voldgade 5-7, DK-1350 Copenhagen (Denmark)
6. Harvard-Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)
7. Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)
8. Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States)
9. Astronomy Department, University of Maryland, College Park, MD 20742 (United States)
10. School of Physics, University of Exeter, Exeter, EX4 4QL (United Kingdom)

We present Gould's Belt (GB) Spitzer IRAC and MIPS observations of the Lupus V and VI clouds and discuss them in combination with near-infrared (2MASS) data. Our observations complement those obtained for other Lupus clouds within the frame of the Spitzer 'Core to Disk' (c2d) Legacy Survey. We found 43 young stellar object (YSO) candidates in Lupus V and 45 in Lupus VI, including two transition disks, using the standard c2d/GB selection method. None of these sources was classified as a pre-main-sequence star from previous optical, near-IR, and X-ray surveys. A large majority of these YSO candidates appear to be surrounded by thin disks (Class III; {approx}79% in Lupus V and {approx}87% in Lupus VI). These Class III abundances differ significantly from those observed for the other Lupus clouds and c2d/GB surveyed star-forming regions, where objects with optically thick disks (Class II) dominate the young population. We investigate various scenarios that can explain this discrepancy. In particular, we show that disk photoevaporation due to nearby OB stars is not responsible for the high fraction of Class III objects. The gas surface densities measured for Lupus V and VI lie below the star formation threshold (A{sub V} {approx} 8.6 mag), while this is not the case for other Lupus clouds. Thus, few Myr older age for the YSOs in Lupus V and VI with respect to other Lupus clouds is the most likely explanation of the high fraction of Class III objects in these clouds, while a higher characteristic stellar mass might be a contributing factor. Better constraints on the age and binary fraction of the Lupus clouds might solve the puzzle but require further observations.

• OSTI ID: 21574613
• Journal Information: Astrophysical Journal, Vol. 730, Issue 2; Other Information: DOI: 10.1088/0004-637X/730/2/65; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
CLOUDS
INTERSTELLAR SPACE
STARS
SPACE