Rotational Velocities for B0-B3 Stars in Seven Young Clusters: Further Study of the Relationship between Rotation Speed and Density in Star-Forming Regions

Subarcsecond radio and infrared observations reveal a class of luminous, obscured, optically thick HII regions associated with extremely large young clusters in nearby starburst galaxies. VLA images show bright radio nebulae with ne ∼ 104 cm−3, densities characteristic of young Galactic compact HII regions. Excitation of the nebulae requires the presence of several thousand O stars within regions of 1-10 pc extent, corresponding to clusters containing 105–106 stars. The compact nebulae are also bright in the mid-infrared, and can for significant fractions of not only the total IR luminosity, but also the total bolometric luminosity, of the parent galaxies. The prototype for these “supernebulae” is the large, obscured cluster in the dwarf galaxy NGC 5253.

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Dense Molecular Clumps Associated with Young Clusters in Massive Star‐forming Regions

The Astrophysical Journal ◽

10.1086/512058 ◽

2007 ◽

Vol 659 (1) ◽

pp. 459-478 ◽

Cited By ~ 32

Author(s):

Hiro Saito ◽

Masao Saito ◽

Kazuyoshi Sunada ◽

Yoshinori Yonekura

Keyword(s):

Massive Star ◽

Star Forming ◽

Star Forming Regions ◽

Young Clusters

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Correlation Between Flare Stars and Other Populations in Young Clusters and Star Forming Regions

Flare Stars in Star Clusters, Associations and the Solar Vicinity ◽

10.1007/978-94-009-0607-5_53 ◽

1990 ◽

pp. 263-265

Author(s):

V. S. Shevchenko ◽

S. D. Yakubov

Keyword(s):

Star Forming ◽

Star Forming Regions ◽

Flare Stars ◽

Young Clusters

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Pre–Main Sequence Evolution of Star Forming Regions and Young Clusters

EAS Publications Series ◽

10.1051/eas/1151013 ◽

2011 ◽

Vol 51 ◽

pp. 245-287 ◽

Cited By ~ 1

Author(s):

F. Palla

Keyword(s):

Main Sequence ◽

Sequence Evolution ◽

Star Forming ◽

Star Forming Regions ◽

Young Clusters

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The W51 Main/South SFR complex seen through 6-GHz OH and methanol masers

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312006862 ◽

2012 ◽

Vol 8 (S287) ◽

pp. 171-175 ◽

Cited By ~ 1

Author(s):

Sandra Etoka ◽

Malcolm D. Gray ◽

Gary A. Fuller

Keyword(s):

Young Stellar Objects ◽

High Mass ◽

Mass Star ◽

Stellar Objects ◽

Maser Emission ◽

Star Forming ◽

Methanol Maser ◽

Star Forming Regions ◽

Relationship Of ◽

The Relationship

AbstractW51 Main/South is one of the brightest and richest high-mass star-forming regions (SFR) in the complex W51. It is known to host many ultra-compact HII (UCHII) regions thought to be the site of massive young stellar objects. Maser emission from various species is also found in the region. We have performed MERLIN astrometric observations of excited-OH maser emission at 6.035 GHz and Class II methanol maser emission at 6.668 GHz towards W51 to investigate the relationship between the maser emission and the compact continuum sources in this SFR complex. Here we present the astrometric distributions of both 6.668-GHz methanol and 6.035-GHz excited-OH maser emission in the W51 Main/South region. The location of maser emission in the two lines is compared with that of previously published OH groundstate emission. The interesting coherent velocity and spatial structure observed in the methanol maser distribution as well as the relationship of the masers to infall or outflow in the region are discussed. It appears that the masers are excited by multiple objects potentially at different stages of evolution.

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Properties of X-ray Flares on Young Stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100035016 ◽

1995 ◽

Vol 151 ◽

pp. 212-215

Author(s):

Th. Preibisch ◽

R. Neuhäuser

Keyword(s):

Solar Flares ◽

Young Stars ◽

Age Dependence ◽

X Ray ◽

Star Forming ◽

Star Forming Regions ◽

Young Clusters ◽

Cluster Age ◽

Very High ◽

Flare Model

AbstractThe interest in the giant flares found on young stars results from the fact that their energetics is vastly different from solar flares. The recent ROSAT observations of young clusters yield a good basis for a systematic study of these flares.We have investigated 18 very deep pointed observations of star forming regions in IC348, Chamaeleon, ρ Ophiuchi, and Orion. To study the age dependence of the flare properties we also investigated the observations of the young clusters IC2391, Pleiades, and Hyades. In this way we have evaluated the X-ray emission of several hundred young stars with ages ranging from about 106 years to 7 ń 108 years. We have found 36 large flares on identified cluster members and have determined the flare properties with a simple flare model.The flares show the same relation between the total X-ray flare energy and the quiescent X-ray luminosity as the dM star flares. The total X-ray flare energies decrease smoothly from the very high values found for very young stars to solar values with increasing cluster age. Our results indicate that the large flares on young stars are similar to scaled-up solar-like activity rather than to accretion processes.

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