scholarly journals Star formation in NGC 3603

1999 ◽  
Vol 193 ◽  
pp. 499-500
Author(s):  
Mauricio Tapia ◽  
Brenda Pérez
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Lower Mass ◽  
The Core ◽  
Near Ir ◽  
H Ii Region ◽  
Very High ◽  
30 Doradus

NGC 3603 is the most massive optically visible H II region in our Galaxy and is considered to be the Galactic analogue to 30 Doradus and, thus, a prototype of the starburst phenomenon. Its core, known as WR 43 (HD 97950), contains several dozens of O-B0 stars within 35″. These have been studied with very high resolution in the optical and near-IR. Melnick, Tapia & Terlevich (1989) concluded that the starburst cluster has an age spread of 1 to 2 Myr and that its boundaries extend to ∼60″, while Eisenhauer et al. (1998) determined that the lower mass stars in the core are younger than 1 Myr.

scholarly journals Dense core structure and fragmentation in the Rho Ophiuchi molecular cloud

1991 ◽  
Vol 147 ◽  
pp. 229-233
Author(s):  
Alwyn Wootten
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Molecular Cloud ◽  
Surface Density ◽  
Core Structure ◽  
Dense Core ◽  
Dense Cores ◽  
Rho Ophiuchi ◽  
Very High ◽  
Taurus Molecular Cloud

About a dozen distinct dense cores have been identified in the Rho Ophiuchi molecular cloud. The properties of these cores are summarized and compared to the properties of cores in the Taurus molecular cloud, a less efficient region of star formation, and in DR21(OH), a more massive region of star formation. The data are consistent with a picture in which more massive clouds have a higher surface density of cores, which in turn are more massive. The adjacent cores in L1689N have been studied with very high resolution; one has formed stars and one never has. The structure of these cores shows a tendency for duplicity of structures from the largest scales (1 pc) to the smallest (50 AU).

scholarly journals Massive Star Formation in W49

1987 ◽  
Vol 115 ◽  
pp. 143-145
Author(s):  
J. Dreher ◽  
S. Vogel ◽  
S. Terebey ◽  
W. J. Welch
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Massive Star ◽  
Hii Regions ◽  
Molecular Line ◽  
The Galaxy ◽  
Molecular Lines ◽  
H Ii Region ◽  
Scale Structures ◽  
The Continuum

W49 is the most luminous H II region complex in the galaxy. VLA maps in the continuum reveal a complex of more than two dozen compact HII regions, including a ring-like distribution of a dozen such regions within a volume of 1 pc. In addition to the VLA maps, we have obtained high resolution maps in this field with the Hat Creek Millimeter Interferometer in the following molecular lines: HCO+(1-0), H13CO+(1-0), SiO(v = 0, J = 2-1), SiO(v = 1, J = 2-1), H13CN(1-0), HC15N(1-0), SO2 [8(3,5)-9(2,8)], SO2[8(1,7)-8(0,8)], SO[2(2)-1(1)], and CH3CH2CN[10(1,10)-9(1,9)], all near 3 mm wavelengh. These maps will be discussed. The HCO+distribution corresponds to the larger scale structures observed in the continuum maps. In contrast the SO and SiO sources are quite compact. Using the detailed molecular line results obtained in the ORION/KL region as a guide, we are able to identify these latter sources as regions in which the star formation is at an earlier stage, regions where there are outflows.

scholarly journals A New Investigation of the 30 Doradus Region with the Australia Telescope Compact Array

1999 ◽  
Vol 190 ◽  
pp. 251-253
Author(s):  
J. S. Lazendic ◽  
R. F. Haynes ◽  
J. R. Dickel ◽  
P. A. Jones ◽  
G. L. White ◽  
...  
Keyword(s):  
Star Formation ◽  
Supernova Remnants ◽  
Massive Stars ◽  
Large Magellanic Cloud ◽  
Complex Nature ◽  
Active Star ◽  
H Ii Region ◽  
The Impact ◽  
Compact Array ◽  
30 Doradus

30 Doradus is a giant H II region in the Large Magellanic Cloud (Bode 1801). It is the nearest extragalactic giant H II region and the location of active star formation. The complex nature of this extended region provides an excellent opportunity to investigate the impact of massive stars on the structure of the interstellar medium. Specifically the presence of supernova remnants (SNRs) is expected to play an important role.

scholarly journals Dense core structure and fragmentation in the Rho Ophiuchi molecular cloud

1991 ◽  
Vol 147 ◽  
pp. 229-233
Author(s):  
Alwyn Wootten
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Molecular Cloud ◽  
Surface Density ◽  
Core Structure ◽  
Dense Core ◽  
Dense Cores ◽  
Rho Ophiuchi ◽  
Very High ◽  
Taurus Molecular Cloud

About a dozen distinct dense cores have been identified in the Rho Ophiuchi molecular cloud. The properties of these cores are summarized and compared to the properties of cores in the Taurus molecular cloud, a less efficient region of star formation, and in DR21(OH), a more massive region of star formation. The data are consistent with a picture in which more massive clouds have a higher surface density of cores, which in turn are more massive. The adjacent cores in L1689N have been studied with very high resolution; one has formed stars and one never has. The structure of these cores shows a tendency for duplicity of structures from the largest scales (1 pc) to the smallest (50 AU).

scholarly journals The Object R136 in the Core of the 30 Doradus Nebula

1984 ◽  
Vol 108 ◽  
pp. 261-261
Author(s):  
W. Seggewiss ◽  
A.F.J. Moffat
Keyword(s):  
Central Object ◽  
The Core ◽  
H Ii Region ◽  
30 Doradus

R136 = HD 38268 is the luminous and diffuse central object (V ~ 10m in a region of 7 arc sec diameter) of the young populous cluster NGC 2070 at the centre of the giant H II region 30 Doradus.

scholarly journals Induced Star Formation in M17: High Resolution NH3 and IR Observations

1987 ◽  
Vol 115 ◽  
pp. 141-142
Author(s):  
M. Felli ◽  
M. Massi ◽  
R. Stanga ◽  
E. Churchwell
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Molecular Cloud ◽  
Type Structure ◽  
Radio Continuum ◽  
Ionization Front ◽  
The South ◽  
The West ◽  
H Ii Region ◽  
Linear Diameter

A VLA radio continuum study of the H II region M17 (Felli, Churchwell and Massi, 1984) has shown the presence of an elongated sharp arc structure in the South Bar of the nebula, in a region of heavy obscuration. The arc has been interpreted as an ionization boundary, viewed edge on, located between the diffuse H II region, to the east, and a dense component of the extended molecular cloud, to the west. About 3″ to the west of this arc, an ultra-compact H II region has been found. This has a shell type structure, a linear diameter of 0.004 pc and probably is the result of induced star formation in the molecular cloud produced by the pressure front preceding the ionization front.

Near-IR Observations of Vega-like Stars with the VLTI: β Pic, α PsA, ∊ Eri and τ Cet

2004 ◽  
Vol 219 ◽  
pp. 75-79 ◽  
Author(s):  
Emmanuel Di Folco ◽  
Pierre Kervella ◽  
Frédéric Thévenin ◽  
Pierre Morel ◽  
Armando Domiciano de Suza ◽  
...  
Keyword(s):  
High Resolution ◽  
Main Sequence ◽  
High Accuracy ◽  
Field Of View ◽  
Circumstellar Material ◽  
Near Ir ◽  
Long Baselines ◽  
Very High ◽  
Innermost Region ◽  
K Band

We have conducted K band interferometric observations of four nearby main-sequence Vega-like stars at the VLTI with very long baselines. The very high resolution allowed us to probe the innermost region of the disks, where planets are supposed to be formed. The diameters of three bright and nearby prototypes β Pictoris, Fomalhaut (α PsA) and ∊ Eridani as well as τ Ceti have been measured with VINCI, the VLTI commissioning instrument, with a high accuracy. The derived diameters were used to constrain their age with help of the evolution code CESAM. The precision achieved with VINCI allowed us to discuss the shape of their photosphere and the possible detection of warm circumstellar material within the narrow interferometric field of view.

scholarly journals Optical and Ultraviolet Spectral Morphology of Luminous OB Stars in the Galaxy and the Magellanic Clouds

1986 ◽  
Vol 116 ◽  
pp. 185-198 ◽  
Author(s):  
Nolan R. Walborn
Keyword(s):  
High Resolution ◽  
Hubble Space Telescope ◽  
Optical Data ◽  
High Resolution Data ◽  
Ob Stars ◽  
Central Cluster ◽  
Distant Galaxies ◽  
The Galaxy ◽  
H Ii Region ◽  
30 Doradus

Three areas of current progress relevant to the theme of this Symposium will be discussed. (1) New spectroscopic observations of the 30 Doradus central cluster, obtained independently by the author and by J. Melnick, confirm the presence of numerous very early O-type members, including several of type O3. In combination with sophisticated new direct imagery of the luminous central object R136 by A. Walker and by G. Weigelt, these results have evident implications for understanding the ionization of the supergiant H II region, as well as for the interpretation of R136 itself and of the apparently similar regions seen in more distant galaxies. In particular, no evidence remains for a supermassive object in 30 Doradus, but its central cluster is revealed as a spectacular grouping of very massive hot stars. (2) A further member of the Ofpe/WN9 category in the LMC has been identified, bringing their number to seven, with no exact spectroscopic counterparts yet known in the Galaxy. One of these objects is currently in a state of outburst and has been interpreted by O. Stahl et al. as the hottest known Hubble-Sandage variable. (3) An extensive survey of IUE high-resolution data has revealed a strong correlation between the ultraviolet stellar wind features and the optical spectral classifications for the majority of normal O stars. These results are relevant to future studies with the High Resolution Spectrograph on the Hubble Space Telescope, which may observe restricted UV wavelength ranges in faint extragalactic OB stars lacking optical data of comparable quality.

scholarly journals The Exciting Stars of Giant Extragalactic H II Regions

1986 ◽  
Vol 116 ◽  
pp. 355-367 ◽  
Author(s):  
Michael Rosa ◽  
Sandro D'Odorico
Keyword(s):  
Star Formation ◽  
H Ii Regions ◽  
Type Ii ◽  
Population Synthesis ◽  
Stellar Content ◽  
Stellar Spectra ◽  
Minimum Frequency ◽  
Nearby Galaxies ◽  
H Ii Region ◽  
Very High

Recent investigations of the stellar content of giant H II regions and star formation bursts in nearby galaxies are summarized. The preliminary results of a spectroscopic survey of 78 H II regions in 15 galaxies are presented. A minimum frequency of 30 percent is found for the occurrence of luminous Wolf-Rayet stars in such bursts of star formation. Observations of the positions of historical type II supernovae revealed the presence of WC stars, indicating very high ZAMS masses for the SN progenitors. The application of population synthesis models to the analysis of the integrated stellar spectra in terms of IMF parameters is discussed. An example of such an analysis for a giant H II region in Cen A is presented.

scholarly journals NGC 604 — A Giant H II Region Dominated by Many WR Stars

1982 ◽  
Vol 99 ◽  
pp. 555-556
Author(s):  
M. Rosa ◽  
S. D'Odorico
Keyword(s):  
The Core ◽  
H Ii Region ◽  
Transition Type ◽  
30 Doradus

NGC 604, the largest H II region in M 33, is comparable in many respects (eg. ionized mass, total extent of a few hundered pc) with the giant H II complex 30 Doradus of the LMC. Recently D'Odorico and Rosa (1981) discovered broad WR emission features at 4640 å, 4660 å, He II 4686 å and 5812 å in a number of the bright knots in the core of NGC 604. In that paper it was concluded, that about 50 WR stars, mainly of the transition type WN 7 but WC characteristica seen as well, are present in the H II region. These findings were confirmed by the observations by Conti and Massey (1981).

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