ROTATIONAL VELOCITIES FOR EARLY-TYPE STARS IN THE YOUNG LARGE MAGELLANIC CLOUD CLUSTER R136: FURTHER STUDY OF THE RELATIONSHIP BETWEEN ROTATION SPEED AND DENSITY IN STAR-FORMING REGIONS

2008 ◽  
Vol 136 (3) ◽  
pp. 1049-1060 ◽  
Author(s):  
S. C. Wolff ◽  
S. E. Strom ◽  
K. Cunha ◽  
S. Daflon ◽  
K. Olsen ◽  
...  
Keyword(s):  
Rotation Speed ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Early Type ◽  
Star Forming ◽  
Star Forming Regions ◽  
Cloud Cluster ◽  
Early Type Stars ◽  
The Relationship

scholarly journals First detection of [13C II] in the Large Magellanic Cloud

2019 ◽  
Vol 631 ◽  
pp. L12 ◽  
Author(s):  
Yoko Okada ◽  
Ronan Higgins ◽  
Volker Ossenkopf-Okada ◽  
Cristian Guevara ◽  
Jürgen Stutzki ◽  
...  
Keyword(s):  
Optical Depth ◽  
Line Profile ◽  
Large Magellanic Cloud ◽  
Abundance Ratio ◽  
Magellanic Cloud ◽  
Star Forming ◽  
Star Forming Regions ◽  
Distant Galaxies ◽  
Nearby Galaxies ◽  
Galactic Sources

Context. [13C II] observations in several Galactic sources show that the fine-structure [12C II] emission is often optically thick (the optical depths around 1 to a few). Aims. Our goal was to test whether this also affects the [12C II] emission from nearby galaxies like the Large Magellanic Cloud (LMC). Methods. We observed three star-forming regions in the LMC with upGREAT on board SOFIA at the frequency of the [C II] line. The 4 GHz bandwidth covers all three hyperfine lines of [13C II] simultaneously. For the analysis, we combined the [13C II] F = 1−0 and F = 1−1 hyperfine components as they do not overlap with the [12C II] line in velocity. Results. Three positions in N159 and N160 show an enhancement of [13C II] compared to the abundance-ratio-scaled [12C II] profile. This is likely due to the [12C II] line being optically thick, supported by the fact that the [13C II] line profile is narrower than [12C II], the enhancement varies with velocity, and the peak velocity of [13C II] matches the [O I] 63 μm self-absorption. The [12C II] line profile is broader than expected from a simple optical depth broadening of the [13C II] line, supporting the scenario of several PDR components in one beam having varying [12C II] optical depths. The derived [12C II] optical depth at three positions (beam size of 14″, corresponding to 3.4 pc) is 1−3, which is similar to values observed in several Galactic sources shown in previous studies. If this also applies to distant galaxies, the [C II] intensity will be underestimated by a factor of approximately 2.

scholarly journals Velocity profiles of [CII], [CI], CO, and [OI] and physical conditions in four star-forming regions in the Large Magellanic Cloud

2019 ◽  
Vol 621 ◽  
pp. A62 ◽  
Author(s):  
Yoko Okada ◽  
Rolf Güsten ◽  
Miguel Angel Requena-Torres ◽  
Markus Röllig ◽  
Jürgen Stutzki ◽  
...  
Keyword(s):  
Physical Properties ◽  
High Redshift ◽  
Line Emission ◽  
Chemical Species ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Continuum Emission ◽  
Line Profiles ◽  
Star Forming ◽  
Star Forming Regions

Aims. The aim of our study is to investigate the physical properties of the star-forming interstellar medium (ISM) in the Large Magellanic Cloud (LMC) by separating the origin of the emission lines spatially and spectrally. The LMC provides a unique local template to bridge studies in the Galaxy and high redshift galaxies because of its low metallicity and proximity, enabling us to study the detailed physics of the ISM in spatially resolved individual star-forming regions. Following Okada et al. (Okada, Y., Requena-Torres, M. A., Güsten, R., et al. 2015, A&A, 580, A54), we investigate different phases of the ISM traced by carbon-bearing species in four star-forming regions in the LMC, and model the physical properties using the KOSMA-τ PDR model. Methods. We mapped 3–13 arcmin2 areas in 30 Dor, N158, N160, and N159 along the molecular ridge of the LMC in [C II] 158 μm with GREAT on board SOFIA. We also observed the same area with CO(2-1) to (6-5), 13CO(2-1) and (3-2), [C I] 3P1–3P0 and 3P2–3P1 with APEX. For selected positions in N159 and 30 Dor, we observed [O I] 145 μm and [O I] 63 μm with upGREAT. All spectra are velocity resolved. Results. In all four star-forming regions, the line profiles of CO, 13CO, and [C I] emission are similar, being reproduced by a combination of Gaussian profiles defined by CO(3-2), whereas [C II] typically shows wider line profiles or an additional velocity component. At several positions in N159 and 30 Dor, we observed the velocity-resolved [O I] 145 and 63 μm lines for the first time. At some positions, the [O I] line profiles match those of CO, at other positions they are more similar to the [C II] profiles. We interpret the different line profiles of CO, [C II] and [O I] as contributions from spatially separated clouds and/or clouds in different physical phases, which give different line ratios depending on their physical properties. We modeled the emission from the CO, [C I], [C II], and [O I] lines and the far-infrared continuum emission using the latest KOSMA-τ PDR model, which treats the dust-related physics consistently and computes the dust continuum SED together with the line emission of the chemical species. We find that the line and continuum emissions are not well-reproduced by a single clump ensemble. Toward the CO peak at N159 W, we propose a scenario that the CO, [C II], and [O I] 63 μm emission are weaker than expected because of mutual shielding among clumps.

scholarly journals Identifying young stellar objects in nine Large Magellanic Cloud star-forming regions

2012 ◽  
Vol 542 ◽  
pp. A66 ◽  
Author(s):  
L. R. Carlson ◽  
M. Sewiło ◽  
M. Meixner ◽  
K. A. Romita ◽  
B. Lawton
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Star Forming ◽  
Star Forming Regions

scholarly journals 3D mapping of young stars in the solar neighbourhood with Gaia DR2

2018 ◽  
Vol 620 ◽  
pp. A172 ◽  
Author(s):  
E. Zari ◽  
H. Hashemi ◽  
A. G. A. Brown ◽  
K. Jardine ◽  
P. T. de Zeeuw
Keyword(s):  
Main Sequence ◽  
Three Dimensional ◽  
Young Stars ◽  
Solar Neighbourhood ◽  
Mass Star ◽  
Early Type ◽  
Star Forming ◽  
Star Forming Regions ◽  
Density Maps ◽  
Early Type Stars

We study the three dimensional arrangement of young stars in the solar neighbourhood using the second release of the Gaia mission (Gaia DR2) and we provide a new, original view of the spatial configuration of the star-forming regions within 500 pc of the Sun. By smoothing the star distribution through a Gaussian filter, we construct three dimensional (3D) density maps for early-type stars (upper-main sequence, UMS) and pre-main sequence (PMS) sources. The PMS and the UMS samples are selected through a combination of photometric and astrometric criteria. A side product of the analysis is a 3D, G-band extinction map, which we use to correct our colour-magnitude diagram for extinction and reddening. Both density maps show three prominent structures, Scorpius-Centaurus, Orion, and Vela. The PMS map shows a plethora of lower-mass star-forming regions, such as Taurus, Perseus, Cepheus, Cassiopeia, and Lacerta, which are less visible in the UMS map due to the lack of large numbers of bright, early-type stars. We report the finding of a candidate new open cluster towards l, b ∼ 218.5° , − 2°, which could be related to the Orion star-forming complex. We estimate ages for the PMS sample and we study the distribution of PMS stars as a function of their age. We find that younger stars cluster in dense, compact clumps, and are surrounded by older sources, whose distribution is instead more diffuse. The youngest groups that we find are mainly located in Scorpius-Centaurus, Orion, Vela, and Taurus. Cepheus, Cassiopeia, and Lacerta are instead more evolved and less numerous. Finally, we find that the 3D density maps show no evidence for the existence of the ring-like structure which is usually referred to as the Gould Belt.

scholarly journals The Stellar Complexes in the Large Magellanic Cloud

1999 ◽  
Vol 190 ◽  
pp. 452-453
Author(s):  
F. Maragoudaki ◽  
M. Kontizas ◽  
E. Kontizas ◽  
A. Dapergolas ◽  
D. H. Morgan
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Top Down ◽  
Star Forming ◽  
Contour Maps ◽  
Fundamental Properties ◽  
Star Forming Regions ◽  
Stellar Complexes

A method has been developed for the detection of stellar complexes and the derivation of their fundamental properties in the LMC. We have used digitized UKST plates in order to perform star counts and produce isodensity contour maps in various colours and luminosity slices. About 50 large stellar groupings have been revealed. Their properties favour a “top-down” mechanism acting in star forming regions.

scholarly journals Coronal C+3 in the LMC: Evidence for a Hot Halo

1999 ◽  
Vol 190 ◽  
pp. 56-60
Author(s):  
Bart Wakker
Keyword(s):  
Spectral Type ◽  
Active Regions ◽  
Sole Source ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Early Type ◽  
Hot Gas ◽  
Hα Emission ◽  
Early Type Stars ◽  
Photo Ionization

Observations of interstellar C IV toward six stars in the Large Magellanic Cloud are described. These data were obtained with the GHRS on HST and with IUE. They provide the first unambiguous evidence that C+3 exists in the Large Magellanic Cloud away from regions where it could have been produced locally, as the six stars are of spectral type later than 08, as well as away from hot early-type stars or active regions. Significant differences between the velocities of the C+3 absorption and those of Hα emission near the stars shows that these ions are not co-spatial, implying that the C+3 originates in the halo of the LMC. It is shown that photo-ionization is unlikely to be the sole source of the C+3 and that the LMC halo thus contains hot gas.

scholarly journals Giant Molecular Cloud Formation at the Interface of Colliding Supershells in the Large Magellanic Cloud

2021 ◽  
Author(s):  
Kosuke Fujii ◽  
Norikazu Mizuno ◽  
J R Dawson ◽  
Tsuyoshi Inoue ◽  
Kazufumi Torii ◽  
...  
Keyword(s):  
Large Magellanic Cloud ◽  
Cloud Formation ◽  
Beam Size ◽  
Star Forming ◽  
Star Forming Regions ◽  
Long Baseline ◽  
Gravitational Instabilities ◽  
Atomic Medium ◽  
High Column ◽  
Compact Array

Abstract We investigate the H i envelope of the young, massive GMCs in the star-forming regions N48 and N49, which are located within the high column density H i ridge between two kpc-scale supergiant shells, LMC 4 and LMC 5. New long-baseline H i 21 cm line observations with the Australia Telescope Compact Array (ATCA) were combined with archival shorter baseline data and single dish data from the Parkes telescope, for a final synthesized beam size of 24.75″ by 20.48″, which corresponds to a spatial resolution of ∼ 6 pc in the LMC. It is newly revealed that the H i gas is highly filamentary, and that the molecular clumps are distributed along filamentary H i features. In total 39 filamentary features are identified and their typical width is ∼ 21 (8–49) [pc]. We propose a scenario in which the GMCs were formed via gravitational instabilities in atomic gas which was initially accumulated by the two shells and then further compressed by their collision. This suggests that GMC formation involves the filamentary nature of the atomic medium.

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