scholarly journals Ring Nebulae Associated with Wolf-Rayet Stars

1982 ◽  
Vol 99 ◽  
pp. 469-472
Author(s):  
Y.-H. Chu

Using strict selection criteria, we have searched for ring nebulae associated with Wolf-Rayet stars in the Galaxy and the Magellanic Clouds. In our search, 15 WR ring nebulae are identified in the Galaxy (Chu 1981a; Chu 1981b, Paper G1), 9 in the Large Magellanic Cloud, and none in the Small Magellanic Cloud (Chu and Lasker 1980, Paper LI; Chu 1981a). We have subsequently observed the morphology and kinematics of these 24 nebulae to study their nature. The data and analyses are reported in G (galactic) and L (LMC) series of papers. These nebulae and their references are listed in Table 1. This table is nearly, but not quite, complete. An extremely careful search might result in more cases, e.g., NGC6357 (Lortet et al. 1981). In a later search by Heckathorn et al. (1982), more ring nebulae are suggested; however, only three cases (associated with HD92740, HD187282, and HD211564) are more convincing. We have obtained some data for these nebulae and will discuss them in a conclusion paper of the galactic series (Chu et al. 1982, Paper G8).

1991 ◽  
Vol 148 ◽  
pp. 161-164 ◽  
Author(s):  
S. van den Bergh

Star clusters in the Magellanic Clouds (MCs) differ from those in the Galaxy in a number of respects: (1) the Clouds contain a class of populous open clusters that has no Galactic counterpart; (2) Cloud clusters have systematically larger radii rh than those in the Galaxy; (3) clusters of all ages in the Clouds are, on average, more flattened than those in the Galaxy. In the Large Magellanic Cloud (LMC) there appear to have been two distinct epochs of cluster formation. LMC globulars have ages of 12-15 Gyr, whereas most populous open clusters have ages <5 Gyr. No such dichotomy is observed for clusters in the Small Magellanic Cloud (SMC) The fact that the SMC exhibits no enhanced cluster formation at times of bursts of cluster formation in the LMC, militates against encounters between the Clouds as a cause for enhanced rates of star and cluster formation.


1984 ◽  
Vol 108 ◽  
pp. 223-224
Author(s):  
Horace A. Smith ◽  
Leo Connolly

The Small Magellanic Cloud is known to contain types of short period Cepheid variable stars not yet discovered in either the Large Magellanic Cloud or, with the exception of a single star, in the Galaxy. These variables can be divided into two categories: anomalous Cepheids and Wesselink-Shuttleworth (WS) stars. The former, which have also been found in dwarf spheroidal systems and in the globular cluster NGC 5466, have periods of 0.4–3 days, but average 0.7–1.0 mag. brighter than RR Lyrae and BL Her stars of equal period. The stars we call WS stars have periods less than about 1.1 day and, at MV = −1 to −2, are brighter than anomalous Cepheids of equal period.


2016 ◽  
Vol 12 (S323) ◽  
pp. 384-385
Author(s):  
Marcin Gładkowski ◽  
Marcin Hajduk ◽  
Igor Soszyński

AbstractThe Optical Gravitational Experiment (OGLE) was effectively used in discovering binary central stars of planetary nebulae (CSPNe). About 50 binary CSPNe have been hitherto identified in the Galaxy, almost half of them were detected in the OGLE database. We used the OGLE data to search for binary CSPNe in the Magellanic Clouds. We also searched for PNe mimics and removed them from the PNe sample. Here, we present results of the photometric analysis for Small Magellanic Cloud (SMC) and our progress on search of binary central stars in the Large Magellanic Cloud (LMC). So far, we have discovered one binary central star of the PN beyond the Milky Way, which is located in the Small Magellanic Cloud.


1991 ◽  
Vol 148 ◽  
pp. 438-439
Author(s):  
Tatiana A. Lozinskaya

The four oxygen-sequence WR stars, Sand 1 in the Small Magellanic Cloud (SMC), Sand 2 in the Large Magellanic Cloud (LMC), and WR 102 and WR 142 in the Galaxy represent the latest stage of the evolution of massive stars (Sanduleak 1971, Barlow and Hummer 1982, Moffatet al.1985). We have shown WR 102 to be a stripped CO core of a supermassive star (Dopitaet al.1990), probably seen only several thousand years before a SN explosion. The four stars are characterized by extremely energetic stellar winds –Vw from 4500 to 7400 km/s (Barlow and Hummer 1982, Dopitaet al.1990, Torreset al.1986). Examination of the environments of WO stars leads to the conclusion that the four objects appear to be associated with optical and/or IR shell-like structures, although the short WO-superwind does not prevail in the shell's formation.


1991 ◽  
Vol 148 ◽  
pp. 15-23 ◽  
Author(s):  
B. E. Westerlund

A vast amount of observational data concerning the structure and kinematics of the Magellanic Clouds is now available. Many basic quantities (e.g. distances and geometry) are, however, not yet sufficiently well determined. Interactions between the Small Magellanic Cloud (SMC), the Large Magellanic Cloud (LMC) and our Galaxy have dominated the evolution of the Clouds, causing bursts of star formation which, together with stochastic self-propagating star formation, produced the observed structures. In the youngest generation in the LMC it is seen as an intricate pattern imitating a fragmented spiral structure. In the SMC much of the fragmentation is along the line of sight complicating the reconstruction of its history. The violent events in the past are also recognizable in complex velocity patterns which make the analysis of the kinematics of the Clouds difficult.


1998 ◽  
Vol 15 (1) ◽  
pp. 128-131 ◽  
Author(s):  
Miroslav D. Filipović ◽  
Paul A. Jones ◽  
Graeme L. White ◽  
Raymond F. Haynes

AbstractWe present a comparison between the latest Parkes radio surveys (Filipović et al. 1995, 1996, 1997) and Hα surveys of the Magellanic Clouds (Kennicutt & Hodge 1986). We have found 180 discrete sources in common for the Large Magellanic Cloud (LMC) and 40 in the field of the Small Magellanic Cloud (SMC). Most of these sources (95%) are HII regions and supernova remnants (SNRs). A comparison of the radio and Hα flux densities shows a very good correlation and we note that many of the Magellanic Clouds SNRs are embedded in HII regions.


1991 ◽  
Vol 148 ◽  
pp. 401-406 ◽  
Author(s):  
Klaas S. De Boer

General aspects of ISM studies using absorption line studies are given and available data are reviewed. Topics are: galactic foreground gas, individual fields in the Magellanic Clouds (MCs) and MC coronae. Overall investigations are discussed. It is demonstrated that the metals in the gas of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) are a factor of 3 and 10, respectively, in abundance below solar levels. The depletion pattern in the LMC is similar to that of the Milky Way.


2018 ◽  
Vol 14 (S344) ◽  
pp. 53-56
Author(s):  
Maria-Rosa L. Cioni ◽  
Florian Niederhofer ◽  
Stefano Rubele ◽  
Ning-Chen Sun

AbstractVISTA observed the Small Magellanic Cloud (SMC), as part of the VISTA survey of the Magellanic Clouds system (VMC), for six years (2010–2016). The acquired multi-epoch YJKs images have allowed us to probe the stellar populations to an exceptional level of detail across an unprecedented wide area in the near-infrared. This contribution highlights the most recent VMC results obtained on the SMC focusing, in particular, on the clustering of young stellar populations, on the proper motion of stars in the main body of the galaxy and on the spatial distribution of the star formation history.


1999 ◽  
Vol 190 ◽  
pp. 569-578 ◽  
Author(s):  
Sidney van den Bergh

Important problems to which we would like to find answers are: •What are the distances to the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC)?•What is the present distribution of stars, gas and dark matter in the Clouds, and how did it evolve?•How, and where, did the Magellanic Clouds form, and how have their orbits evolved?•Finally the recent discovery of numerous microlensing events in the Clouds provides answers to questions that we have only recently started to ask.


1999 ◽  
Vol 186 ◽  
pp. 60-60
Author(s):  
A.M. Yoshizawa ◽  
M. Noguchi

The system of the Magellanic Clouds is considered to be dynamically interacting among themselves and with our Galaxy. This interaction is thought to be the cause of many complicated features seen in the Magellanic Clouds and the Magellanic Stream (see Westerlund 1990, A&AR, 2, 27). In order to better understand the formation and evolution of the Magellanic System, we carry out realistic N-body simulations of the tidal distortion of the Small Magellanic Cloud (SMC) due to our Galaxy and the Large Magellanic Cloud (LMC).


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