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Start Over Subject magellanic clouds Validation Level 2
371. Multiwavelength survey of WR stars in LMC
ID:
ivo://CDS.VizieR/J/ApJS/252/21
Title:
Multiwavelength survey of WR stars in LMC
Short Name:
J/ApJS/252/21
Date:
21 Oct 2021
Publisher:
CDS
Description:
Surveys of Wolf-Rayet (WR) stars in the Large Magellanic Cloud (LMC) have yielded a fairly complete catalog of 154 known stars. We have conducted a comprehensive, multiwavelength study of the interstellar/circumstellar environments of WR stars, using the Magellanic Cloud Emission Line Survey images in the H{alpha}, [OIII], and [SII] lines; Spitzer Space Telescope 8 and 24{mu}m images; Blanco 4m Telescope H{alpha} CCD images; and Australian Telescope Compact Array + Parkes Telescope HI data cube of the LMC. We have also examined whether the WR stars are in OB associations, classified the HII environments of WR stars, and used this information to qualitatively assess the WR stars' evolutionary stages. The 30 Dor giant HII region has active star formation and hosts young massive clusters, thus we have made statistical analyses for 30 Dor and the rest of the LMC both separately and altogether. Due to the presence of massive young clusters, the WR population in 30 Dor is quite different from that from elsewhere in the LMC. We find small bubbles (<50pc diameter) around ~12% of WR stars in the LMC, most of which are WN stars and not in OB associations. The scarcity of small WR bubbles is discussed. Spectroscopic analyses of abundances are needed to determine whether the small WR bubbles contain interstellar medium or circumstellar medium. Implications of the statistics of interstellar environments and OB associations around WR stars are discussed. Multiwavelength images of each LMC WR star are presented.
372. N159 ^12^CO and ^13^CO (2-1) clumps
ID:
ivo://CDS.VizieR/J/ApJ/854/154
Title:
N159 ^12^CO and ^13^CO (2-1) clumps
Short Name:
J/ApJ/854/154
Date:
21 Oct 2021
Publisher:
CDS
Description:
The N159 star-forming region is one of the most massive giant molecular clouds (GMCs) in the Large Magellanic Cloud (LMC). We show the ^12^CO, ^13^CO, CS molecular gas lines observed with ALMA in N159 west (N159W) and N159 east (N159E). We relate the structure of the gas clumps to the properties of 24 massive young stellar objects (YSOs) that include 10 newly identified YSOs based on our search. We use dendrogram analysis to identify properties of the molecular clumps, such as flux, mass, linewidth, size, and virial parameter. We relate the YSO properties to the molecular gas properties. We find that the CS gas clumps have a steeper size-linewidth relation than the ^12^CO or ^13^CO gas clumps. This larger slope could potentially occur if the CS gas is tracing shocks. The virial parameters of the ^13^CO gas clumps in N159W and N159E are low (<1). The threshold for massive star formation in N159W is 501M_{sun}_/pc^2^, and the threshold for massive star formation in N159E is 794M_{sun}_/pc^2^. We find that ^13^CO is more photodissociated in N159E than N159W. The most massive YSO in N159E has cleared out a molecular gas hole in its vicinity. All the massive YSO candidates in N159E have a more evolved spectral energy distribution type in comparison to the YSO candidates in N159W. These differences lead us to conclude that the giant molecular cloud complex in N159E is more evolved than the giant molecular cloud complex in N159W.
373. Near-IR spectra of LMC globular clusters
ID:
ivo://CDS.VizieR/J/A+A/543/A75
Title:
Near-IR spectra of LMC globular clusters
Short Name:
J/A+A/543/A75
Date:
21 Oct 2021
Publisher:
CDS
Description:
The rest-frame near-IR spectra of intermediate age (1-2Gyr) stellar populations are dominated by carbon based absorption features offering a wealth of information. Yet, spectral libraries that include the near-IR wavelength range do not sample a sufficiently broad range of ages and metallicities to allow for accurate calibration of stellar population models and thus the interpretation of the observations. In this paper we investigate the integrated J- and H-band spectra of six intermediate age and old globular clusters in the Large Magellanic Cloud (LMC).
374. Nebulae in the Magellanic Clouds
ID:
ivo://CDS.VizieR/VII/232
Title:
Nebulae in the Magellanic Clouds
Short Name:
VII/232
Date:
21 Oct 2021
Publisher:
CDS
Description:
Long exposures of the complexes of ionized hydrogen in both the LMC and SMC have been taken with the 48-in. SRC Schmidt camera through an H{alpha}+[N II] interference filter to 100{AA} bandwidth. These plates and identifying charts are presented here in a form in which little information is lost. A catalog of many individual emission regions in both these galaxies is also compiled.
375. New planetary nebulae in LMC
ID:
ivo://CDS.VizieR/J/MNRAS/365/401
Title:
New planetary nebulae in LMC
Short Name:
J/MNRAS/365/401
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report our initial discovery of 73 new planetary nebulae (PNe) in the Large Magellanic Cloud (LMC) following confirmatory 2dF spectroscopy on the Anglo-Australian Telescope. Preliminary candidate sources come from a 10 per cent sub-area of our new deep, high-resolution H{alpha} map of the central 25deg^2^ of the LMC obtained with the UK Schmidt Telescope. The depth of the high-resolution map was extended to R_equiv_~22 for H{alpha} (4.5x10^-17^erg/cm^2^/s/{AA}) by a process of multi-exposure median co-addition of a dozen 2-h H{alpha} exposures. The resulting map is at least 1-mag deeper than the best wide-field narrow-band LMC images currently available. This depth, combined with our selection technique, has also led to the discovery of extended asymptotic giant branch (AGB) haloes around many new and previously known LMC PNe for the first time. Once complete, our new survey is expected to triple the LMC PN population and have significant implications for the LMC PN luminosity function, kinematics, abundance gradients, chemical evolution and, via study of the AGB haloes, the initial to final mass relation for low- to intermediate-mass stars.
376. New SMC planetary nebulae
ID:
ivo://CDS.VizieR/J/AJ/123/269
Title:
New SMC planetary nebulae
Short Name:
J/AJ/123/269
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the ESO 2.2m telescope with the 8Kx8K mosaic CCD, we have surveyed 2.8deg^2^ (~1.6{deg}x1.7{deg}) of the Small Magellanic Cloud (SMC) to search for faint planetary nebulae (PNs); 34 PNs were previously known in this central region. We identified 25 new PNs, all faint and spectroscopically confirmed.
377. New star clusters in the Magellanic system
ID:
ivo://CDS.VizieR/J/AcA/67/363
Title:
New star clusters in the Magellanic system
Short Name:
J/AcA/67/363
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Magellanic System (MS) encompasses the nearest neighbors of the Milky Way, the Large (LMC) and Small (SMC) Magellanic Clouds, and the Magellanic Bridge (MBR). This system contains a diverse sample of star clusters. Their parameters, such as the spatial distribution, chemical composition and age distribution yield important information about the formation scenario of the whole Magellanic System. Using deep photometric maps compiled in the fourth phase of the Optical Gravitational Lensing Experiment (OGLE-IV) we present the most complete catalog of star clusters in the Magellanic System ever constructed from homogeneous, long time-scale photometric data. In this second paper of the series, we show the collection of star clusters found in the area of about 360 square degrees in the MBR and in the outer regions of the SMC. Our sample contains 198 visually identified star cluster candidates, 75 of which were not listed in any of the previously published catalogs. The new discoveries are mainly young small open clusters or clusters similar to associations.
378. New survey of supergiants in the MCs
ID:
ivo://CDS.VizieR/J/A+A/578/A3
Title:
New survey of supergiants in the MCs
Short Name:
J/A+A/578/A3
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this study, we conduct a pilot program aimed at the red supergiant population of the Magellanic Clouds. We intend to extend the current known sample to the unexplored low end of the brightness distribution of these stars, building a more representative dataset with which to extrapolate their behaviour to other Galactic and extra-galactic environments. We select candidates using only near infrared photometry, and with medium resolution multi-object spectroscopy, we perform spectral classification and derive their line-of-sight velocities, confirming the nature of the candidates and their membership to the clouds. Around two hundred new RSGs have been detected, hinting at a yet to be observed large population. Using near and mid infrared photometry we study the brightness distribution of these stars, the onset of mass-loss and the effect of dust in their atmospheres. Based on this sample, new a priori classification criteria are investigated, combining mid and near infrared photometry to improve the observational efficiency of similar programs as this.
379. NGC 2004
ID:
ivo://CDS.VizieR/J/AJ/102/137
Title:
NGC 2004
Short Name:
J/AJ/102/137
Date:
21 Oct 2021
Publisher:
CDS
Description:
The results of a new CCD photometric investigation of stars in the field of the LMC cluster NGC 2004 are reported and discussed. B, V photometry is given for more than 1500 objects, the large majority to be ascribed to the cluster. A new color-magnitude diagram is presented. It shows a well-defined blue sequence (BS) of H-burning stars, running from V~=21mag up to V~=13mag, together with a group of cluster He-burning red supergiants with V~=13mag and a clump of field red giants at about V~=19 mag. Theoretical evolutionary computations are reported covering the range of massive stars evolving in the cluster. These evolutionary tracks can match the observed CM diagram provided that a low efficiency of the surface convection (a low value of the mixing length) is adopted. Comparison of the theoretical luminosity function with the upper portion of the observed BS distribution suggests a cluster age of about 8 million years, in agreement with previous evaluations. The completeness of the sample and the contribution of field stars have been estimated. The CM distribution of cluster stars has been compared with the results of synthetic clusters based on the adopted evolutionary scenario. We find that the observed distribution of cluster stars in the different evolutionary phases appears in good agreement with prediction based on theoretical evolutionary lifetimes. Moreover, the distribution of H-burning stars agrees with a Salpeter distribution in the whole range 2<=M/M_{sun}_<=20. After a short review of the current theoretical scenario concerning massive stars, the CM diagram of field stars is discussed, reaching the conclusion that the observed clump of red giants is the natural consequence of the peculiar large lifetimes in the central He burning phase of stars with M~=3M_{sun}_.
380. NGC 330 Be stars and binaries
ID:
ivo://CDS.VizieR/J/A+A/472/577
Title:
NGC 330 Be stars and binaries
Short Name:
J/A+A/472/577
Date:
21 Oct 2021
Publisher:
CDS
Description:
Observations of hot stars belonging to the young cluster SMC-NGC 330 and its surrounding region were obtained with the VLT-GIRAFFE facilities in MEDUSA mode. We investigated the B and Be star properties and proportions in this environment of low metallicity. We also searched for rapid variability in Be stars using photometric databases. Using spectroscopic measurements, we characterized the emission and properties of Be stars. By cross-correlation with photometric databases such as MACHO and OGLE, we searched for binaries in our sample of hot stars, as well as for short-term variability in Be stars. We report on the global characteristics of the Be star sample.