- ID:
- ivo://CDS.VizieR/J/MNRAS/454/1468
- Title:
- LMC post-AGB, post-RGB star and YSOs
- Short Name:
- J/MNRAS/454/1468
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out a search for optically visible post-Asymptotic Giant Branch (post- AGB) stars in the Large Magellanic Cloud (LMC). First, we selected candidates with a mid-IR excess and then obtained their optical spectra. We disentangled contaminants with unique spectra such as M-stars, C-stars, planetary nebulae, quasi-stellar objects and background galaxies. Subsequently, we performed a detailed spectroscopic analysis of the remaining candidates to estimate their stellar parameters such as effective temperature, surface gravity (logg), metallicity ([Fe/H]), reddening and their luminosities. This resulted in a sample of 35 likely post-AGB candidates with late-G to late-A spectral types, low logg, and [Fe/H]<-0.5. Furthermore, our study con- firmed the existence of the dusty post-Red Giant Branch (post-RGB) stars, discovered previously in our SMC survey, by revealing 119 such objects in the LMC. These objects have mid-IR excesses and stellar parameters (Teff, logg, [Fe/H]) similar to those of post-AGB stars except that their luminosities (<2500L_{sun}_), and hence masses and radii, are lower. These post-RGB stars are likely to be products of binary interaction on the RGB. The post-AGB and post-RGB objects show SED properties similar to the Galactic post-AGB stars, where some have a surrounding circumstellar shell, while some others have a surrounding stable disc similar to the Galactic post-AGB binaries. This study also resulted in a new sample of 162 young stellar objects, identified based on a robust logg criterion. Other interesting outcomes include objects with an UV continuum and an emission line spectrum; luminous supergiants; hot main-sequence stars; and 15 B[e] star candidates, 12 of which are newly discovered in this study.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/78
- Title:
- LMC pre-main sequences stars mass accretion rates
- Short Name:
- J/MNRAS/421/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multiwavelength study of three star-forming regions, spanning the age range 1-14Myr, located between the 30 Doradus complex and supernova SN 1987A in the Large Magellanic Cloud (LMC). We reliably identify about 1000 pre-main-sequence (PMS) star candidates actively undergoing mass accretion and estimate their stellar properties and mass accretion rate (dM/dt). Our measurements represent the largest dM/dt data set of low-metallicity stars presented so far. As such, they offer a unique opportunity to study on a statistical basis the mass accretion process in the LMC and, more in general, the evolution of the mass accretion process around low-metallicity stars.
- ID:
- ivo://CDS.VizieR/J/A+A/423/97
- Title:
- LMC RR Lyrae radial velocities
- Short Name:
- J/A+A/423/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the radial velocities, metallicities and the K-band magnitudes of 74 RR Lyrae stars in the inner regions of the LMC. The intermediate resolution spectra and infrared images were obtained with FORS1 at the ESO VLT and with the SOFI infrared imager at the ESO NTT.
- ID:
- ivo://CDS.VizieR/J/AJ/137/4810
- Title:
- LMC-SAGE AGB star candidates
- Short Name:
- J/AJ/137/4810
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present empirical relations describing excess emission from evolved stars in the Large Magellanic Cloud (LMC) using data from the Spitzer Space Telescope Surveying the Agents of a Galaxy's Evolution (SAGE) survey which includes the Infrared Array Camera (IRAC) 3.6, 4.5, 5.8, and 8.0um and Multiband Imaging Photometer (MIPS) 24, 70, and 160um bands. We combine the SAGE data with the Two Micron All Sky Survey (2MASS; J, H, and Ks) and the optical Magellanic Cloud Photometric Survey (MCPS; U, B, V, and I) point source catalogs in order to create complete spectral energy distributions (SEDs) of the asymptotic giant branch (AGB) star candidates in the LMC. AGB star outflows are among the main producers of dust in a galaxy, and this mass loss results in an excess in the fluxes observed in the 8 and 24um bands. The aim of this work is to investigate the mass loss return by AGB stars to the interstellar medium of the LMC by studying the dependence of the infrared excess flux on the total luminosity.
- ID:
- ivo://CDS.VizieR/J/AJ/136/18
- Title:
- LMC SAGE. New candidate YSOs
- Short Name:
- J/AJ/136/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ~1000 new candidate Young Stellar Objects (YSOs) in the Large Magellanic Cloud selected from Spitzer Space Telescope data, as part of the Surveying the Agents of a Galaxy's Evolution (SAGE) Legacy program. The YSOs, detected by their excess infrared (IR) emission, represent early stages of evolution, still surrounded by disks and/or infalling envelopes. Previously, fewer than 20 such YSOs were known. The candidate YSOs were selected from the SAGE Point Source Catalog from regions of color-magnitude space least confused with other IR-bright populations.
- ID:
- ivo://CDS.VizieR/J/AJ/137/3139
- Title:
- LMC SAGE. New variable evolved stars and YSOs
- Short Name:
- J/AJ/137/3139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present initial results and source lists of variable sources in the Large Magellanic Cloud (LMC) for which we detect thermal infrared variability from the Surveying the Agents of a Galaxy's Evolution (SAGE) survey, which had two epochs of photometry separated by 3 months. The SAGE survey mapped a 7{deg}x7{deg} region of the LMC using the Infrared Array Camera (IRAC) and the MIPS instruments on board Spitzer. Variable sources are identified using a combination of the IRAC 3.6, 4.5, 5.8, 8.0um bands and the MIPS 24um bands. An error-weighted flux difference between the two epochs is used to assess the variability. Of the ~3 million sources detected at both epochs, we find ~2000 variable sources for which we provide electronic catalogs. Most of the variable sources can be classified as asymptotic giant branch (AGB) stars. A large fraction (>66%) of the extreme AGB stars are variable and only smaller fractions of carbon-rich (6.1%) and oxygen-rich (2.0%) stars are detected as variable sources. We also detect a population of variable young stellar object candidates.
- ID:
- ivo://CDS.VizieR/J/A+A/621/A62
- Title:
- 4 LMC SFRs velocity profile maps
- Short Name:
- J/A+A/621/A62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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. (2015A&A...580A..54O), 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-{tau} PDR model. We mapped 3-13 arcmin^2^ areas in 30 Dor, N158, N160, and N159 along the molecular ridge of the LMC in [C II] 158 {mu}m with GREAT on board SOFIA. We also observed the same area with CO(2-1) to (6-5), ^13^CO(2-1) and (3-2), [C I] ^3^P_1_-^3^P_0_ and ^3^P_2_-^3^P_1_ with APEX. For selected positions in N159 and 30 Dor, we observed [O I] 145 {mu}m and [O I] 63 {mu}m with upGREAT. All spectra are velocity resolved. In all four star-forming regions, the line profiles of CO, ^13^CO, 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 {mu}m 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-{tau} 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 {mu}m emission are weaker than expected because of mutual shielding among clumps.
- ID:
- ivo://CDS.VizieR/J/ApJ/811/145
- Title:
- LMC & SMC evolved stars detected with Herschel
- Short Name:
- J/ApJ/811/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using observations from the Herschel Inventory of The Agents of Galaxy Evolution (HERITAGE) survey of the Magellanic Clouds (MC), we have found 35 evolved stars and stellar end products that are bright in the far-infrared. These 28 (LMC) and 7 (SMC) sources were selected from the 529 evolved star candidates in the HERITAGE far-infrared point source catalogs. Our source identification method is based on spectral confirmation, spectral energy distribution characteristics, careful examination of the multiwavelength images and includes constraints on the luminosity, resulting in a thoroughly vetted list of evolved stars. These sources span a wide range in luminosity and hence initial mass. We found 13 low- to intermediate-mass evolved stars, including asymptotic giant branch (AGB) stars, post-AGB stars, planetary nebulae, and a symbiotic star. We also identify 10 high mass stars, including 4 of the 15 known B[e] stars in the MC, 3 extreme red supergiants that are highly enshrouded by dust, a Luminous Blue Variable, a Wolf-Rayet star, and two supernova remnants. Further, we report the detection of 9 probable evolved objects which were previously undescribed in the literature. These sources are likely to be among the dustiest evolved objects in the MC. The Herschel emission may either be due to dust produced by the evolved star or it may arise from swept-up interstellar medium material.
- ID:
- ivo://CDS.VizieR/J/ApJS/75/407
- Title:
- LMC & SMC PNe optical spectroscopy. I
- Short Name:
- J/ApJS/75/407
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectroscopy in the range 3300-7400A for a total of 30 planetary nebulae in the LMC and 11 in the SMC, with measurements of line intensities down to ~1% of H{beta}. Agreement with other authors is on the whole excellent, especially for lines >+10%-20% of H{beta}. Reddening estimates from Balmer line ratios have been determined, and the line intensities dereddened accordingly. Nebular [O III] electron temperature and, where measurable, [N II] temperatures and [S II] densities are given. [O II] electron densities are recalculated using appropriate electron temperatures. A number of spectra exhibit interesting spectral features (including symbiotic-type profiles, unidentified emission lines, and nonsimple Balmer decrements). These objects are discussed in some detail. Zanstra temperatures are derived for a total of 25 objects possessing detectable stellar continua. These temperatures are in agreement with the few published values from various methods, and preliminary photoionization modeling of this sample. The homogeneity and size of the sample make it possible to investigate several interesting correlations between measured parameters.
- ID:
- ivo://CDS.VizieR/J/ApJS/76/1085
- Title:
- LMC & SMC PNe optical spectroscopy. II
- Short Name:
- J/ApJS/76/1085
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectroscopy in the range 3300-7400A for a total of 37 planetary nebulae in the LMC and seven in the SMC. Together with the object from the first paper in the series (1991ApJS...75..407M), we now have accurate emission-line intensities down to a few percent of H{beta} for 77 nebulae in the Magellanic Clouds. Agreement with other authors is excellent. Reddening estimates from Balmer line ratios have been determined, and the line intensities have been dereddened accordingly. Nebular [O III] electron temperature and, where measurable, [S II] densities, are derived. [O II] electron densities are recalculated using appropriate electron temperatures. The [S II] and [O II] electron densities correlate well, with n_e_([O II])>n_e_([S II]). Zanstra temperatures are in derived for 22 objects possessing detectable stellar continua. These temperatures are in agreement with photoionization modeling of this sample.
