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A Search for Star Formation in the Translucent Cloud MBM 40The star formation status of the translucent high-latitude molecular cloud, MBM 40, is explored through analysis of radio, infrared, optical, and X-ray data. With a peak visual extinction of 1 to 2 mag, MBM 40 is an example of a high-latitude cloud near the diffuse/translucent demarcation. However, unlike most translucent clouds, MBM 40 exhibits a compact morphology and a kinetic energy-to gravitational potential energy ratio near unity. Our radio data, encompassing the CO (J = 1-0), CS (J = 2-1), and H2CO 1(sub 11-1(sub 10), spectral line transitions, reveal that the cloud contains a ridge of molecular gas with n greater than or equal to 10(exp 3)/ cc. In addition, the molecular data, together with IRAS data, indicate that the mass of MBM 40 is approx. 40 solar mass. In light of the ever-increasing number of recently formed stars far from any dense molecular clouds or cores, we searched the environs of MBM 40 for any trace of recent star formation. We used the ROSAT All-Sky Survey X-ray data and a ROSAT PSPC pointed observation toward MBM 40 to identify 33 stellar candidates with properties consistent with pre-main-sequence (PMS) stars. Follow-up optical spectroscopy of the candidates with V less than 15.5 was conducted with the 1.5 m Fred Lawrence Whipple Observatory telescope in order to identify signatures of T Tauri or pre-main- sequence stars (such as the Li 6708 A resonance line). Since none of our optically observed candidates display standard PMS signatures, we conclude that MBM 40 displays no evidence of recent or ongoing star formation. The absence of high-density molecular cores in the cloud and the relatively low column density compared to star-forming interstellar clouds may be the principal reasons that MBM 40 is devoid of star formation. More detailed comparison between this cloud and other, higher extinction translucent and dark clouds may elucidate the necessary initial conditions for the onset of low-mass star formation.
Document ID
19990008009
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Magnani, Loris
(Georgia Univ. Athens, GA United States)
Caillault, Jean-Pierre
(Georgia Univ. Athens, GA United States)
Hearty, Thomas
(Georgia Univ. Athens, GA United States)
Stauffer, John
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA United States)
Schmitt, J. H. M. M.
(Max-Planck-Inst. fuer Extraterrestrische Physik Garching, Germany)
Neuhaeuser, Ralph
(Max-Planck-Inst. fuer Extraterrestrische Physik Garching, Germany)
Verter, Frances
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Dwek, Eli
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
August 19, 2013
Publication Date
July 10, 1996
Publication Information
Publication: Astrophysical Journal
Publisher: American Astronomical Society
Volume: 465
ISSN: 0004-637X
Subject Category
Astronomy
Funding Number(s)
CONTRACT_GRANT: NAG5-1610
CONTRACT_GRANT: NAGw-2698
CONTRACT_GRANT: NAG5-2665
Distribution Limits
Public
Copyright
Other

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