Nothing to Hide - Mid-infrared and X-ray Surveys of Star Formation Activity in the Pipe Nebula

Author(s)

Jan Forbrich, C. J. Lada, A. Muench, J. Alves, M. Lombardi, B. Posselt, K. Covey

Abstract

The Pipe Nebula, a large nearby molecular cloud, lacks obvious signposts

of star formation in all but one of more than 130 dust extinction cores

that have been identified within it. In order to quantitatively

determine the current level of star formation activity in the Pipe

Nebula, we analyzed 13 square degrees of sensitive mid-infrared maps of

the entire cloud, obtained with the Multiband Imaging Photometer for

Spitzer at wavelengths of 24 micron and 70 micron, to search for

candidate young stellar objects (YSOs) in the high-extinction regions.

We argue that our search is complete for class I and typical class II

YSOs with bolometric luminosities of about 0.2 solar luminosities and

greater. We find only 18 candidate YSOs in the high-extinction regions

of the entire Pipe cloud. Twelve of these sources are previously known

members of a small cluster associated with Barnard 59, the largest and

most massive dense core in the cloud. With only six candidate class I

and class II YSOs detected toward extinction cores outside of this

cluster, our findings emphatically confirm the notion of an extremely

low level of star formation activity in the Pipe Nebula. The resulting

star formation efficiency for the entire cloud mass is only 0.06%.

X-ray observations allow us to extend our survey to constrain any

population of classical and weak-line T Tauri stars. In a first step, we

use the ROSAT All-Sky Survey to constrain any overall T Tauri star

population of the Pipe Nebula. Subsequently, we use XMM-Newton

observations pointed at three high-extinction regions within the Pipe

Nebula to analyze these regions at higher sensitivity. The X-ray data

contain no indications of an additional YSO population and corroborate

our previous Spitzer result that the star formation efficiency of the

Pipe Nebula is extremely low.

Organisation(s)

Department of Astrophysics

External organisation(s)

Harvard-Smithsonian Center for Astrophysics, European Southern Observatory (Germany), Cornell University

Journal

Bulletin of the American Astronomical Society

Volume

Pages

257

ISSN

0002-7537

Publication date

01-2010

Austrian Fields of Science 2012

103004 Astrophysics

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