- ID:
- ivo://CDS.VizieR/J/ApJS/184/1
- Title:
- Molecular clouds in the LMC by NANTEN. II.
- Short Name:
- J/ApJS/184/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We studied star formation activities in the molecular clouds in the Large Magellanic Cloud. We have utilized the second catalog of 272 molecular clouds obtained by NANTEN (4m radio telescope of Nagoya University at Las Campanas Observatory, Chile) to compare the cloud distribution with signatures of massive star formation including stellar clusters, and optical and radio HII regions. We find that the molecular clouds are classified into three types according to the activities of massive star formation: Type I shows no signature of massive star formation; Type II is associated with relatively small HII region(s); and Type III with both HII region(s) and young stellar cluster(s). The radio continuum sources were used to confirm that Type I giant molecular clouds (GMCs) do not host optically hidden HII regions. These signatures of massive star formation show a good spatial correlation with the molecular clouds in the sense that they are located within ~100pc of the molecular clouds.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/136/1221
- Title:
- Most luminous LMC sources at 8{mu}m
- Short Name:
- J/AJ/136/1221
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To ascertain the nature of the brightest compact mid-infrared (mid-IR) sources in the Large Magellanic Cloud (LMC), we have applied an updated version of Buchanan et al.'s (2006AJ....132.1890B) Two Micron All Sky Survey (2MASS)-Midcourse Space Experiment (MSX) color classification system, which is based on the results of Spitzer Space Telescope spectroscopy, to a mid-IR (8um) flux-limited sample of 250 LMC objects for which 2MASS and MSX photometry is available. The resulting 2MASS-MSX ("JHK8") color-based classifications of these sources, which constitute the most mid-IR-luminous objects in the LMC, were augmented, cross-checked, and corrected where necessary via a variety of independent means, such that only 46 sources retain tentative classifications and only 10 sources cannot be classified at all. The sample is found to consist primarily of carbon-rich asymptotic giant branch (AGB) stars (35%), red supergiants (RSGs) (18%), and compact HII regions (32%), with additional, small populations of oxygen-rich AGB stars (~5%), dusty, early-type emission-line stars (~3%), and foreground, O-rich AGB stars in the Milky Way (~3%).
- ID:
- ivo://CDS.VizieR/J/ApJ/775/92
- Title:
- MQS III: AGNs behind LMC and SMC
- Short Name:
- J/ApJ/775/92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Magellanic Quasars Survey (MQS) has now increased the number of quasars known behind the Magellanic Clouds by almost an order of magnitude. All survey fields in the Large Magellanic Cloud (LMC) and 70% of those in the Small Magellanic Cloud (SMC) have been observed. The targets were selected from the third phase of the Optical Gravitational Lensing Experiment (OGLE-III) based on their optical variability, mid-IR, and/or X-ray properties. We spectroscopically confirmed 758 quasars (565 in the LMC and 193 in the SMC) behind the clouds, of which 94% (527 in the LMC and 186 in the SMC) are newly identified. The MQS quasars have long-term (12yr and growing for OGLE), high-cadence light curves, enabling unprecedented variability studies of quasars. The MQS quasars also provide a dense reference grid for measuring both the internal and bulk proper motions of the clouds, and 50 quasars are bright enough (I<~18mag) for absorption studies of the interstellar/intergalactic medium of the clouds.
- ID:
- ivo://CDS.VizieR/J/MNRAS/355/1196
- Title:
- MS bands of SiC_2_ in LMC carbon stars
- Short Name:
- J/MNRAS/355/1196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From a sample of 304 carbon stars in the central parts of the Large Magellanic Cloud (LMC), ~27 per cent have Merrill-Sanford (MS) bands of the SiC2 molecule. The data are based on a uniform set of spectra taken with 2dF on the Anglo-Australian Telescope, and give useful statistics on the incidence of MS bands and on their correlation (or otherwise) with other properties. All of these are red stars, cooler than 3100 K. The proportion of stars showing the bands is highest amongst the coolest stars, but not all very cool stars show the bands. There is no evidence that MS bands are more common in J-type stars (carbon stars with a high ^13^C/^12^C ratio) than in N-type carbon stars, at least within this sample of LMC stars. There is no apparent correlation with stellar variability, or between the photospheric temperature [as measured by (J-K)] and the occurrence of the 'hot' MS bands from excited molecular states.
- ID:
- ivo://CDS.VizieR/J/AJ/122/1844
- Title:
- MSX and 2MASS cross-correlation in LMC
- Short Name:
- J/AJ/122/1844
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Large Magellanic Cloud (LMC) has been observed by the Midcourse Space Experiment (MSX) in the mid-infrared and the Two Micron All Sky Survey (2MASS) in the near-infrared. We have performed a cross-correlation of the 1806 MSX catalog sources and nearly 1.4 million 2MASS catalogued point and extended sources and find 1664 matches. Using the available color information, we identify a number of stellar populations and nebulae, including main-sequence stars, giant stars, red supergiants, carbon- and oxygen-rich asymptotic giant branch (AGB) stars, planetary nebulae, H II regions, and other dusty objects likely associated with early-type stars. A total of 731 of these sources have no previous identification. We compile a listing of all objects, which includes photometry and astrometry. The 8.3{mu}m MSX sensitivity is the limiting factor for object detection: only the brighter red objects, specifically the red supergiants, AGB stars, planetary nebulae, and H II regions, are detected in the LMC. The remaining objects are likely in the Galactic foreground. The spatial distribution of the infrared LMC sources may contribute to understanding stellar formation and evolution and the overall galactic evolution. We demonstrate that a combined mid- and near-infrared photometric baseline provides a powerful means of identifying new objects in the LMC for future ground-based and space-based follow-up observations.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A29
- Title:
- Multiplicity of red supergiants in NGC 330
- Short Name:
- J/A+A/635/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The multiplicity properties of massive stars are one of the important outstanding issues in stellar evolution. Quantifying the binary statistics of all evolutionary phases is essential to paint a complete picture of how and when massive stars interact with their companions, and to determine the consequences of these interactions. We investigate the multiplicity of an almost complete census of red supergiant stars (RSGs) in NGC 330, a young massive cluster in the Small Magellanic Cloud. Using a combination of multi-epoch HARPS and MUSE spectroscopy, we estimate radial velocities and assess the kinematic and multiplicity properties of 15 RSGs in NGC 330. Radial velocities are estimated to better than +/-100m/s for the HARPS data. The line-of-sight velocity dispersion for the cluster is estimated as {sigma}_1D_=3.20^+0.69^_-0.52_km/s. When virial equilibrium is assumed, the dynamical mass of the cluster is log(M_dyn_/M_{sun}_)=5.20+/-0.17, in good agreement with previous upper limits. We detect significant radial velocity variability in our multi-epoch observations and distinguish between variations caused by atmospheric activity and those caused by binarity. The binary fraction of NGC 330 RSGs is estimated by comparisons with simulated observations of systems with a range of input binary fractions. In this way, we account for observational biases and estimate the intrinsic binary fraction for RSGs in NGC 330 as f_RSG_=0.3+/-0.1 for orbital periods in the range 2.3<logP[days]<4.3, with q>0.1. Using the distribution of the luminosities of the RSG population, we estimate the age of NGC 330 to be 45+/-5Myr and estimate a red straggler fraction of 50%. We estimate the binary fraction of RSGs in NGC 330 and conclude that it appears to be lower than that of main-sequence massive stars, which is expected because interactions between an RSG and a companion are assumed to effectively strip the RSG envelope.
- 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.
- 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.
- 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).
- 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.
