Astronomy and Astrophysics – Astronomy
Scientific paper
Dec 2010
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010apj...725.2461t&link_type=abstract
The Astrophysical Journal, Volume 725, Issue 2, article id. 2461-2479 (2010).
Astronomy and Astrophysics
Astronomy
2
Ism: Individual Objects: L673 Cb188, Stars: Formation, Stars: Pre-Main Sequence, Stars: Protostars
Scientific paper
L673 and CB188 are two low-mass clouds isolated from large star-forming regions that were observed as part of the Spitzer Legacy Project "From Molecular Clouds to Planet Forming disks" (c2d). We identified and characterized all the young stellar objects (YSOs) of these two regions and modeled their spectral energy distributions (SEDs) to examine whether their physical properties are consistent with values predicted from the theoretical models and with the YSO properties in the c2d survey of larger clouds. Overall, 30 YSO candidates were identified by the c2d photometric criteria, 27 in L673 and 3 in CB188. We confirm the YSO nature of 29 of them and remove a false Class III candidate in L673. We further present the discovery of two new YSO candidates, one Class 0 and another possible Class I candidate in L673, therefore bringing the total number of YSO candidates to 31. Multiple sites of star formation are present within L673, closely resembling other well-studied c2d clouds containing small groups such as B59 and L1251B, whereas CB188 seems to consist of only one isolated globule-like core. We measure a star formation efficiency (SFE) of 4.6%, which resembles the SFE of the larger c2d clouds. From the SED modeling of our YSO sample we obtain envelope masses for Class I and Flat spectrum sources of 0.01-1.0 M sun. The majority of Class II YSOs show disk accretion rates from 3.3 × 10-10 to 3 × 10-8 M sun yr-1 and disk masses that peak at 10-4 to 10-3 M sun. Finally, we examined the possibility of thermal fragmentation in L673 as the main star-forming process. We find that the mean density of the regions where significant YSO clustering occurs is of the order of ~105 cm-3 using 850 μm observations and measure a Jeans Length that is greater than the near-neighbor YSO separations by approximately a factor of 3-4. We therefore suggest that other processes, such as turbulence and shock waves, may have had a significant effect on the cloud's filamentary structure and YSO clustering.
Bourke Tyler L.
Dunham Michael M.
Evans Neal J. II
Huard Tracy L.
Myers Philip C.
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