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  • 1
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    Near-infrared observations of young stellar objects in the Rho Ophiuchi dark cloud (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: We have conducted an imaging survey of 1.4 sq pc of the Rho Ophiuchi dark cloud in the J, H, and K near-infrared photometric bands. Approximately 337 of our 481 detected sources are associated with the cloud, and we estimate that 48 percent of these have near-infrared excesses, indicative of disks or circumstellar material surrounding these young stellar objects (YSOs). The K-band luminosity function is significantly different in different regions of our survey area, suggesting that YSOs in these regions have different ages or mass functions. We estimate that the entire survey area has a high star-formation efficiency, at roughly 23 percent. Finally, our many newly detected sources provide a relatively large, uniformly sensitive sample of objects for study at longer wavelengths to better determine true source luminosities and evolutionary lifetimes.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 395; 2 Au; 516-528
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  • 2
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    The Rho Ophiuchi cloud young stellar population - Results of a near-infrared study (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: An imaging survey of 1.4 sq pc of the Rho Ophiuchi dark cloud in the J, H, and K near-infrared photometric bands was conducted. Approximately 332 of the 481 detected sources are associated with the cloud, and 30 percent of these have near-infrared excesses, indicative of disks or circumstellar material surrounding these young stellar objects (YSOs). The K-band luminosity function is significantly different in different regions of the survey area, suggesting that YSOs in these regions have different ages or mass functions. The entire survey area has a high star formation efficiency of about 23 percent. Finally, many newly detected sources provide a relatively large, uniformly sensitive sample of objects for study at longer wavelengths to better determine true source luminosities and evolutionary lifetimes.
    Keywords: ASTROPHYSICS
    Type: Societa Astronomica Italiana, Memorie (ISSN 0037-8720); 62; 4 19
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  • 3
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    IRAS observations of dust heating and energy balance in the Rho Ophiuchi dark cloud (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The equilibrium process dust emission in the Rho Ophiuchi dark cloud is studied. The luminosity of the cloud is found to closely match the luminosity of the clouds's known embedded and external radiation sources. There is no evidence for a large population of undetected low-luminosity sources within the cloud and unknown external heating is also only a minor source of energy. Most of the cloud's luminosity is emitted in the mid-to-far-IR. Dust temperature maps indicate that the dust is not hot enough to heat the gas to observed temperatures. A simple cloud model with a radiation field composed of flux HD 147889, S1, and Sco OB2 associations predicts the observed IRAS 60 to 100 micron in-band flux ratios for a mean cloud density n(H2) = 1400. Flattened 12 and 25 micron observations show much extended emission in these bands, suggesting stochastic heating of very small grains or large molecules.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 339; 258-267
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  • 4
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    IRAS observations of young stellar objects in the Corona Australis dark cloud (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The young stellar object (YSO) population associated with the dark cloud complex in Corona Australis is studied by synthesizing IRAS data with newly obtained near-IR and mid-IR photometry and previously published optical/IR data. Twenty-four YSOs in the Cr A complex are identified. The observed range of spectral energy distribution shapes and bolometric luminosities are consistent with those observed in other dark clouds. The duration and efficiency of star formation are found to be similar to the Rho Ophiuchi IR cluster. The low number of YSOs compared to other dark clouds is understood by a reevaluation of the molecular mass of the R Cr A cloud which shows it to be much less massive than previously assumed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 397; 2; p. 520-533.
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  • 5
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    Young stellar objects in the Monoceros OB1 molecular cloud (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Detailed results of an IRAS survey of a large portion of the Monoceros OB1 molecular cloud for discrete far-IR sources are presented. IRAS spectral energy distributions are constructed for 27 of the 30 sources identified in the region. Many are bright class I energy distributions, indicating that star formation is still occurring in the complex which produced the visible cluster, NGC 2264. Far-IR luminosities are calculated for each source, and the bolometric luminosity functions for class I and class II sources in the Mon OB1 cloud are found to be significantly different. Of all class I and II sources more luminous than 5 solar, 50 percent of class I sources are more luminous than 60 solar while only 4 percent of class II sources are. An attempt is made to determine the type of young stellar object in the cloud with which molecular outflows are associated.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 345; 906-917
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  • 6
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    An unusual outflow around IRAS 16293-2422 (1988)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: The dense dusty molecular cloud core associated with the unusual protostellar source IRAS 16293-1422 (IRAS 1629A) was observed in the J = 2-1 transition of (C-12)O and (C-13)O. These observations indicate that IRAS 1629A is a source of an unusual high-velocity molecular outflow with four separate emission lobes. The morphology and velocity structure of the lobes may suggest the presence of a dual jet or double bipolar outflow system originating from the vicinity of IRAS 1269A. These observations resolve the outflowing gas into numerous high-velocity clumps which are either being continuously accelerated from low to high velocity along the entire length of the flow or are undergoing free-flow expansion.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 332; 335-345
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  • 7
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    Spectroscopic evidence for infall around an extraordinary IRAS source in Ophiuchus (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Millimeter-wave continuum observations and spectral line observations of the J = 5-4 and J = 2-1 transitions of CS toward IRAS 16293-2422, an extremely cold infrared source associated with a high-velocity molecular outflow in the Rho Ophiuchi molecular cloud, are reported. The observations indicate that this source is a dust-enshrouded object embedded in a dense, elongated configuration of molecular gas whose major axis is roughly orthogonal to the direction of the double bipolar outflow observed in it. The observations appear to provide spectroscopic evidence for significant mass infall motions associated with a young stellar object, and suggest that IRAS 16293-2422 is a true protostar.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 309; L47-L51
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  • 8
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    Infrared images of the young cluster NGC 2264 (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-08-27
    Description: Initial results of an extensive IR imaging survey of the young cluster NGC 2264 and a nearby galactic control field are presented. A large portion of the cluster was imaged in each of the three standard near-IR colors (J, H, and K) with an IR array camera. On the basis of a comparison of these observations, the size of the cluster population is estimated, and the nature of its members is investigated. The cluster is found to contain 360 +/- 130 members. The slope of the K luminosity function of the cluster is significantly steeper than that expected for a cluster of ZAMS stars, and appears to flatten out or turn over at an apparent K magnitude of roughly 13.0-14.0. An analysis of the JHK color-color diagrams of the cluster and control fields shows that approximately 170 sources observed toward the cluster have colors indicative of intrinsic excess IR emission.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 408; 2; p. 471-483.
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