http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
The earliest phases of high-mass star formation, as seen in NGC 6334 by <i>Herschel</i>-HOBYS
Tigé,, J.,Motte, F.,Russeil, D.,Zavagno, A.,Hennemann, M.,Schneider, N.,Hill, T.,Nguyen Luong, Q.,Di Francesco, J.,Bontemps, S.,Louvet, F.,Didelon, P.,Kö,nyves, V.,André,, Ph.,Leuleu, Springer-Verlag 2017 Astronomy and astrophysics Vol.602 No.-
High-mass Star Formation through Filamentary Collapse and Clump-fed Accretion in G22
Yuan, Jinghua,Li, Jin-Zeng,Wu, Yuefang,Ellingsen, Simon P.,Henkel, Christian,Wang, Ke,Liu, Tie,Liu, Hong-Li,Zavagno, Annie,Ren, Zhiyuan,Huang, Ya-Fang American Astronomical Society 2018 The Astrophysical journal Vol.852 No.1
<P>How mass is accumulated from cloud-scale down to individual stars is a key open question in understanding highmass star formation. Here, we present the mass accumulation process in a hub-filament cloud G22 that is composed of four supercritical filaments. Velocity gradients detected along three filaments indicate that they are collapsing with a total mass infall rate of about 440M(circle dot) Myr(-1), suggesting the hub mass would be doubled in six free-fall times, adding up to similar to 2 Myr. A fraction of the masses in the central clumps C1 and C2 can be accounted for through large-scale filamentary collapse. Ubiquitous blue profiles in HCO+. (3-2) and (CO)-C-13. (3-2) spectra suggest a clump-scale collapse scenario in the most massive and densest clump C1. The estimated infall velocity and mass infall rate are 0.31 km s(-1) and 7.2 x. 10(-4)M(circle dot) yr(-1), respectively. In clump C1, a hot molecular core (SMA1) is revealed by the Submillimeter Array observations and an outflow-driving high-mass protostar is located at the center of SMA1. The mass of the protostar is estimated to be 11-15M(circle dot) and it is still growing with an accretion rate of 7 x. 10(-5)M(circle dot) yr(-1). The coexistent infall in filaments, clump C1, and the central hot core in G22 suggests that pre-assembled mass reservoirs (i.e., high-mass starless cores) may not be required to form high-mass stars. In the course of high-mass star formation, the central protostar, the core, and the clump can simultaneously grow in mass via core-fed/disk accretion, clump-fed accretion, and filamentary/cloud collapse.</P>
High-mass Starless Clumps in the Inner Galactic Plane: The Sample and Dust Properties
Yuan, Jinghua,Wu, Yuefang,Ellingsen, Simon P.,II, Neal J. Evans,Henkel, Christian,Wang, Ke,Liu, Hong-Li,Liu, Tie,Li, Jin-Zeng,Zavagno, Annie American Astronomical Society 2017 The Astrophysical journal Supplement series Vol.231 No.1
<P>We report a sample of 463 high-mass starless clump (HMSC) candidates within -60 degrees < l < 60 degrees and -1 degrees < b < 1 degrees. This sample has been singled out from 10,861 ATLASGAL clumps. None of these sources are associated with any known star-forming activities collected in SIMBAD and young stellar objects identified using color-based criteria. We also make sure that the HMSC candidates have neither point sources at 24 and 70 mu m. nor strong extended emission at 24 mu m. Most of the identified HMSCs are infrared dark, and some are even dark at 70 mu m. Their distribution shows crowding in Galactic spiral arms and toward the Galactic center and some wellknown star-forming complexes. Many HMSCs are associated with large-scale filaments. Some basic parameters were attained from column density and dust temperature maps constructed via fitting far-infrared and submillimeter continuum data to modified blackbodies. The HMSC candidates have sizes, masses, and densities similar to clumps associated with Class II methanol masers and H. II. regions, suggesting that they will evolve into star-forming clumps. More than 90% of the HMSC candidates have densities above some proposed thresholds for forming high-mass stars. With dust temperatures and luminosity-to-mass ratios significantly lower than that for star-forming sources, the HMSC candidates are externally heated and genuinely at very early stages of high-mass star formation. Twenty sources with equivalent radii r(eq) < 0.15 pc and mass surface densities Sigma > 0.08 g cm(-2) could be possible high-mass starless cores. Further investigations toward these HMSCs would undoubtedly shed light on comprehensively understanding the birth of high-mass stars.</P>
INTERACTIONS OF THE INFRARED BUBBLE N4 WITH ITS SURROUNDINGS
Liu, Hong-Li,Li, Jin-Zeng,Wu, Yuefang,Yuan, Jing-Hua,Liu, Tie,Dubner, G.,Paron, S.,Ortega, M. E.,Molinari, Sergio,Huang, Maohai,Zavagno, Annie,Samal, Manash R.,Huang, Ya-Fang,Zhang, Si-Ju American Astronomical Society 2016 The Astrophysical journal Vol.818 No.1
<P>The physical mechanisms that induce the transformation of a certain mass of gas in new stars are far from being well understood. Infrared bubbles associated with H II regions have been considered to be good samples for investigating triggered star formation. In this paper we report on the investigation of the dust properties of the infrared bubble N4 around the H II. region G11.898+0.747, analyzing its interaction with its surroundings and star formation histories therein, with the aim of determining the possibility of star formation triggered by the expansion of the bubble. Using Herschel PACS and SPIRE images with a wide wavelength coverage, we reveal the dust properties over the entire bubble. Meanwhile, we are able to identify six dust clumps surrounding the bubble, with a mean size of 0.50 pc, temperature of about 22 K, mean column density of 1.7 x 10(22) cm(-2), mean volume density of about 4.4 x 10(4) cm(-3), and a mean mass of 320M(circle dot). In addition, from PAH emission seen at 8 mu m, free-free emission detected at 20 cm, and a probability density function in special regions, we could identify clear signatures of the influence of the H II region on the surroundings. There are hints of star formation, though further investigation is required to demonstrate that N4 is the triggering source.</P>