scholarly journals The Stellar Content of 30 Doradus

1984 ◽  
Vol 108 ◽  
pp. 243-253
Author(s):  
Nolan R. Walborn
Keyword(s):  
Large Magellanic Cloud ◽  
Stellar Content ◽  
Multiple Systems ◽  
Central Cluster ◽  
Distant Galaxies ◽  
Good Accord ◽  
The Galaxy ◽  
Spectroscopic Information ◽  
H Ii Region ◽  
30 Doradus

The supergiant H II region 30 Doradus is placed in context as the optically most spectacular component in a much larger region of recent and current star formation in the Large Magellanic Cloud, as shown by deep Hα photographs and the new IRAS results. The current state of knowledge concerning the concentrated central cluster in 30 Dor is summarized. Spectroscopic information exists for only 24 of the brightest members, most of which are WR stars; however, photometry shows over 100 probable members earlier than BO. The spectral classification of these stars is a difficult observational problem currently being addressed; in the meantime their hypothetical ionizing luminosity is calculated from the photometry and compared with that suggested for the superluminous central object R136a alone, and with the H II region luminosity. With reference to related regions in the Galaxy, the likelihood that many of the brightest objects in 30 Dor are multiple systems is emphasized. An interpretation of R136a as a system containing a few very massive stars (as opposed to a single supermassive object) is in good accord with the observations, including the visual micrometer results. The study of 30 Dor and its central cluster is vital for an understanding of the numerous apparently similar regions now being discovered in more distant galaxies.

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 Luminous Stellar Content of 30 Doradus and NGC 3603 - The Nearest Visible Giant HII Regions

1986 ◽  
Vol 116 ◽  
pp. 233-234
Author(s):  
A.F.J. Moffat ◽  
M.M. Shara ◽  
W. Seggewiss
Keyword(s):  
Spatial Resolution ◽  
Hii Regions ◽  
Stellar Content ◽  
Distant Galaxies ◽  
The Galaxy ◽  
30 Doradus

30 Dor in the LMC and NGC 3603 in the Galaxy are the nearest visible examples of similar giant (or even more massive supergiant) HII regions being studied in other more distant galaxies, where spatial resolution is a much more serious problem. Hence, understanding 30 Dor and NGC 3603 may provide important clues to understanding extragalactic giant HII regions in general.

scholarly journals Galactic starburst NGC 3603 from X-rays to radio

2003 ◽  
Vol 212 ◽  
pp. 515-522
Author(s):  
Anthony F.J. Moffat ◽  
Keyword(s):  
Mass Function ◽  
Initial Mass Function ◽  
X Rays ◽  
Stellar Content ◽  
Near Ir ◽  
The Galaxy ◽  
The Status ◽  
H Ii Region ◽  
Mass Segregation ◽  
Colliding Winds

While NGC 3603 is often quoted as the most massive visible Giant H ii Region in the Galaxy, there are other similar and even more massive regions now being found towards the inner Galaxy in the near-IR. Nevertheless, NGC 3603 still retains the status of clone to the dense core-object in 30 Dor, R 136 — but 7x closer and 49x less crowded! This paper summarizes the most recent findings concerning NGC 3603's color-magnitude diagram (CMD), initial mass function (IMF), mass segregation and stellar content — including its unusually luminous H-rich WNL members — down to its pre-main-sequence stars near the H-burning limit. Of special relevance are new high-resolution X-ray and radio images as related to merging/colliding winds and three massive proplyd-like objects. NGC 3603 is a somewhat younger, hotter, scaled-down version of typical starbursts found in other galaxies.

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 Superassociations in distant galaxies

1964 ◽  
Vol 20 ◽  
pp. 122-126 ◽  
Author(s):  
V. A. Ambartsumian
Keyword(s):  
Special Class ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Photographic Images ◽  
Large Complex ◽  
Distant Galaxies ◽  
Absolute Brightness ◽  
30 Doradus

It is well known that the Large Magellanic Cloud contains in addition to a considerable number of ordinary O-associations a certain number of large objects which, however, are similar in nature to the associations. These objects were named “constellations” by Shapley. But the large complex 30 Doradus surpasses notably all of these objects both in diameter and in absolute brightness. The latter is of the order of −15m0 while its diameter is of the order of 600 pc. If we take the average absolute brightness of associations in our Galaxy as equal to −10m0 then it turns out that 30 Doradus is 100 times more luminous than the ordinary associations. The photographic images of more distant galaxies reveal that sometimes complexes occur in them of the same order of luminosity and dimensions as 30 Doradus. Therefore it seems to us useful to regard these complexes as a special class of objects and call them superassociations.

scholarly journals The stellar content of NGC 3603

1999 ◽  
Vol 193 ◽  
pp. 403-411
Author(s):  
Laurent Drissen
Keyword(s):  
Main Sequence ◽  
Stellar Content ◽  
The Galaxy ◽  
H Ii Region ◽  
Low Mass

At the heart of the galactic giant H II region NGC 3603, low-mass (1–4 M⊙) stars slowly contract toward the main sequence, while peacefully cohabiting with the three most luminous, hydrogen-rich Wolf-Rayet stars in the Galaxy, a dozen hot O3–4 stars and their more modest but numerous O and B companions. This is the story of a very young and dense starburst cluster …

scholarly journals Radiative and mechanical feedback into the molecular gas in the Large Magellanic Cloud

2019 ◽  
Vol 628 ◽  
pp. A113 ◽  
Author(s):  
M.-Y. Lee ◽  
S. C. Madden ◽  
F. Le Petit ◽  
A. Gusdorf ◽  
P. Lesaffre ◽  
...  
Keyword(s):  
Far Infrared ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Continuum Emission ◽  
Molecular Gas ◽  
Stellar Content ◽  
Low Velocity ◽  
Line Energy ◽  
Star Forming ◽  
30 Doradus

With an aim of probing the physical conditions and excitation mechanisms of warm molecular gas in individual star-forming regions, we performed Herschel SPIRE Fourier Transform Spectrometer (FTS) observations of 30 Doradus in the Large Magellanic Cloud. In our FTS observations, important far-infrared (FIR) cooling lines in the interstellar medium, including CO J = 4–3 to J = 13–12, [C I] 370 μm, and [N II] 205 μm, were clearly detected. In combination with ground-based CO J = 1–0 and J = 3–2 data, we then constructed CO spectral line energy distributions (SLEDs) on ~10 pc scales over a ~60 pc × 60 pc area and found that the shape of the observed CO SLEDs considerably changes across 30 Doradus. For example, the peak transition Jp varies from J = 6–5 to J = 10–9, while the slope characterized by the high-to-intermediate J ratio α ranges from ~0.4 to ~1.8. To examine the source(s) of these variations in CO transitions, we analyzed the CO observations, along with [C II] 158 μm, [C I] 370 μm, [O I] 145 μm, H2 0–0 S(3), and FIR luminosity data, using state-of-the-art models of photodissociation regions and shocks. Our detailed modeling showed that the observed CO emission likely originates from highly compressed (thermal pressure P∕kB ~ 107–109 K cm−3) clumps on ~0.7–2 pc scales, which could be produced by either ultraviolet (UV) photons (UV radiation field GUV ~ 103–105 Mathis fields) or low-velocity C-type shocks (pre-shock medium density npre ~ 104–106 cm−3 and shock velocity vs ~ 5–10 km s−1). Considering the stellar content in 30 Doradus, however, we tentatively excluded the stellar origin of CO excitation and concluded that low-velocity shocks driven by kiloparsec-scale processes (e.g., interaction between the Milky Way and the Magellanic Clouds) are likely the dominant source of heating for CO. The shocked CO-bright medium was then found to be warm (temperature T ~ 100–500 K) and surrounded by a UV-regulated low-pressure component (P∕kB ~ a few (104 –105) K cm−3) that is bright in [C II] 158 μm, [C I] 370 μm, [O I] 145 μm, and FIR dust continuum emission.

scholarly journals The Luminosity of the Central Parsec of the Galaxy

1989 ◽  
Vol 136 ◽  
pp. 423-436
Author(s):  
M. W. Werner ◽  
J. A. Davidson
Keyword(s):  
Near Infrared ◽  
Galactic Center ◽  
Thermal Emission ◽  
Large Magellanic Cloud ◽  
Infrared Emission ◽  
Infrared Observations ◽  
The Galaxy ◽  
Infrared Wavelengths ◽  
Central Parsec ◽  
30 Doradus

The luminosity of the central 5 pc of the Galaxy -encompassing the inner regions of the rotating ring of dust and gas which surrounds the galactic center - emerges primarily at infrared wavelengths in the form of thermal emission from heated dust. The nature and location of the sources which heat the dust can be inferred from the spatial and temperature distribution of the thermal infrared emission (λ>20um), from studies of the ionized gas in this region, and from direct imaging in the near infrared. These observations show that the principal heating sources within this 5-pc region are concentrated within the central parsec of the Galaxy and indicate that the luminosity of these sources is within a factor of two of 107 LO. The near-infrared observations of the compact sources at the galactic center do not reveal a single dominant source but suggest instead that the several components of the IRS-16 complex, taken together, may contribute the bulk of the luminosity; however, the data also permit a single object to dominate the energetics of this region. We draw attention to the striking morphological similarities between the galactic center and the innermost regions of the 30 Doradus nebula in the Large Magellanic Cloud and speculate that the luminosity sources in the galactic center may resemble the early-type supergiants in 30 Doradus.

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