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Post Info TOPIC: IRAM 04191+1522
Blobrana


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RE: IRAM 04191+1522
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Title: Discovery of A Binary System in IRAM 04191+1522
Authors: Xuepeng Chen (1), Hector G. Arce (1), Michael M. Dunham (1), Qizhou Zhang (2) ((1) Yale Astronomy Department, (2) Harvard-Smithsonian Center for Astrophysics)

We present high angular resolution observations of the Class 0 protostar IRAM04191+1522, using the Submillimeter Array (SMA). The SMA 1.3 mm continuum images reveal within IRAM04191+1522 two distinct sources with an angular separation of 7.8±0.2". The two continuum sources are located in the southeast-northwest direction, with total gas masses of about 0.011 solar masses and about 0.005 solar masses, respectively. The southeastern source, associated with an infrared source seen in the Spitzer images, is the well-known Class 0 protostar with a bolometric luminosity of about 0.08 L_sun. The newly-discovered northwestern continuum source is not visible in the Spitzer images at wavelengths from 3.6 to 70 micron, and has an extremely low bolometric luminosity (< 0.03 L_sun). Complementary IRAM N2H+(1-0) data that probe the dense gas in the common envelope suggest that the two sources were formed through the rotational fragmentation of an elongated dense core. Furthermore, comparisons between IRAM04191+1522 and other protostars suggest that most cores with binary systems formed therein have ratios of rotational energy to gravitational energy \beta_{rot} > 1%. This is consistent with theoretical simulations and indicates that the level of rotational energy in a dense core plays an important role in the fragmentation process.

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Blobrana


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Title: The Spitzer c2d Survey of Nearby Dense Cores: I: First Direct Detection of the Embedded Source in IRAM 04191+1522
Authors: M. M. Dunham, N. J. Evans II, T. L. Bourke, C. P. Dullemond, C. H. Young, T. Y. Brooke, N. Chapman, P. C. Myers, A. Porras, W. Spiesman, P. J. Teuben, Z. Wahhaj

Researchers report the first detections of the Class 0 protostellar source IRAM 04191+1522 at wavelengths shortward of 60 microns with the Spitzer Space Telescope. The researchers see extended emission in the Spitzer images that suggests the presence of an outflow cavity in the circumstellar envelope. They combine the Spitzer observations with existing data to form a complete dataset ranging from 3.6 to 1300 microns and use these data to construct radiative transfer models of the source.
They conclude that the internal luminosity of IRAM 04191+1522, defined to be the sum of the luminosity from the internal sources (a star and a disk), is Lint = 0.08 ±0.04 Lsun, placing it among the lowest luminosity protostars known. Though it was discovered before the launch of the Spitzer Space Telescope, IRAM 04191+1522 falls within a new class of Very Low Luminosity Objects being discovered by Spitzer. Unlike the two other well-studied objects in this class, which are associated either with weak, compact outflows or no outflows at all, IRAM 04191+1522 has a well-defined molecular outflow with properties consistent with those expected based on relations derived from higher luminosity (Lint > 1 Lsun) protostars. The researchers discuss the difficulties in understanding IRAM 04191+1522 in the context of the standard model of star formation, and suggest a possible explanation for the very low luminosity of this source.

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-- Edited by Blobrana at 12:26, 2006-08-01

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