- ID:
- ivo://CDS.VizieR/J/ApJ/795/108
- Title:
- Stellar populations in the Magellanic bridge
- Short Name:
- J/ApJ/795/108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a young stellar bridge that forms a continuous connection between the Magellanic Clouds. This finding is based on number density maps for stellar populations found in data gathered by OGLE-IV that fully cover over 270 deg^2^ of the sky in the Magellanic Bridge area. This is the most extensive optical survey of this region to date. We find that the young population is present mainly in the western half of the MBR, which, together with the newly discovered young population in the eastern Bridge, form a continuous stream of stars connecting both galaxies along {delta}~-73.5 deg. The young population distribution is clumped, with one of the major densities close to the SMC and the other fairly isolated and located approximately mid-way between the Clouds, which we call the OGLE island. These overdensities are well matched by H I surface density contours, although the newly found young population in the eastern Bridge is offset by ~2 deg north from the highest H I density contour. We observe a continuity of red clump stars between the Magellanic Clouds which represent an intermediate-age population. Red clump stars are present mainly in the southern and central parts of the Magellanic Bridge, below its gaseous part, and their presence is reflected by a strong deviation from the radial density profiles of the two galaxies. This may indicate either a tidal stream of stars, or that the stellar halos of the two galaxies overlap. On the other hand, we do not observe such an overlap within an intermediate-age population represented by the top of the red giant branch and the asymptotic giant branch stars. We also see only minor mixing of the old populations of the Clouds in the southern part of the Bridge, represented by the lowest part of the red giant branch.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/476/114
- Title:
- Stellar properties of Kron 3 stars
- Short Name:
- J/MNRAS/476/114
- Date:
- 02 Nov 2021 11:26:14
- Publisher:
- CDS
- Description:
- We present the results of a spectroscopic study of the intermediate age (~=6.5Gyr) massive cluster Kron 3 in the Small Magellanic Cloud. We measure CN and CH band strengths (at ~=3839 and 4300{AA}, respectively) using VLT FORS2 spectra of 16 cluster members and find a sub-population of five stars enriched in nitrogen. We conclude that this is evidence for multiple populations in Kron 3, the fourth intermediate age cluster, after Lindsay 1, NGC 416 and NGC 339 (ages 6-8Gyr), to display this phenomenon originally thought to be a unique characteristic of old globular clusters. At ~=6.5Gyr this is one of the youngest clusters with multiple populations, indicating that the mechanism responsible for their onset must operate until a redshift of at least 0.75, much later than the peak of globular cluster formation at redshift ~3.
- ID:
- ivo://CDS.VizieR/J/ApJ/622/294
- Title:
- STIS UV spectra of LMC planetary nebulae
- Short Name:
- J/ApJ/622/294
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We acquired spectra of 24 LMC planetary nebulae (PNs) in the 1150-3000{AA} range in order to determine carbon and other ionic abundances. The sample more than doubles the number of LMC PNs with high-quality UV spectra in this wavelength range and whose optical images are available in the Hubble Space Telescope archive. The Space Telescope Imaging Spectrograph was used with a very large aperture to obtain virtually slitless spectra; thus, the monochromatic images in the major nebula emission lines are also available. The analysis of the data shows extremely high quality spectra. This paper presents the emission lines identified and measured and the calculation of the ionic abundances of the emitting carbon and other ions, as well as total carbon abundance.
- ID:
- ivo://CDS.VizieR/J/AJ/120/1808
- Title:
- Stroemgren photometry in LMC disk
- Short Name:
- J/AJ/120/1808
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report new metallicity determinations for 39 red giants in a 220 arcmin2^2^ region, 1.8{deg} southwest of the bar of the Large Magellanic Cloud. These abundance measurements are based on spectroscopy of the Ca II infrared triplet.
- ID:
- ivo://CDS.VizieR/J/AJ/157/49
- Title:
- Stroemgren photometry in the field of NGC 1978
- Short Name:
- J/AJ/157/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the spread of [Fe/H] values in the massive Large Magellanic Cloud cluster NGC 1978, recently confirmed to harbor multiple populations of nearly the same age. We used accurate Stroemgren photometry of carefully selected cluster red giant branch stars along with a high-dispersion spectroscopy-based calibration of the metallicity-sensitive index m_1_. Once we accounted for the photometry quality, assessed from extensive artificial star tests to trace the photometric uncertainties as a function of the position of the cluster's center as well as the stellar brightness, and those from the metallicity calibration, we found that NGC 1978 exhibits a small metallicity spread of 0.035 dex (+/-0.019-0.023), depending on whether stars with individual {sigma}[Fe/H]=<0.15 dex or those located in the cluster's outer areas are considered. Such a spread in [Fe/H] is consistent with a cluster formation model with self-enrichment, if mass loss higher than 90% due to stellar evolutionary and galactic tidal effects is assumed. Nevertheless, scenarios in which the apparent [Fe/H] variation reflects CN abundance anomalies or less extreme mass-loss models with environmentally dependent self-enrichment should not be ruled out.
- ID:
- ivo://CDS.VizieR/J/other/Ser/178.65
- Title:
- Strongest radio point sources in LMC field
- Short Name:
- J/other/Ser/178.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the 100 strongest 1.4GHz point sources from a new mosaic image in the direction of the Large Magellanic Cloud (LMC). The observations making up the mosaic were made using Australia Telescope Compact Array (ATCA) over a ten year period and were combined with Parkes single dish data at 1.4GHz to complete the image for short spacing. An initial list of co-identifications within 1000 at 0.843, 4.8 and 8.6GHz consisted of 2682 sources. Elimination of extended objects and artifact noise allowed the creation of a refined list containing 1988 point sources.
- ID:
- ivo://CDS.VizieR/J/AJ/131/414
- Title:
- Structural parameters of SMC star clusters
- Short Name:
- J/AJ/131/414
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present structural parameters for 204 stellar clusters in the Small Magellanic Cloud derived from fitting King and Elson, Fall, and Freeman (EFF, 1987ApJ...323...54E) model profiles to the V-band surface brightness profiles as measured from the Magellanic Clouds Photometric Survey images.
- ID:
- ivo://CDS.VizieR/III/147
- Title:
- Studies of LMC stellar content
- Short Name:
- III/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A spectral survey has been made during the period 1971 to 1975 with the ESO 40cm astrograph at La Silla, equipped with its normal prism, giving an intermediate dispersion of 95Angstroem/mm at 4026Angstroem. Long exposure plates taken directly or with an interference filter enabled us to obtain spectral types for nearly 1600 stars. In parallel, a V photographic survey has been carried out during the same period with the same astrograph and has led to the determination of V magnitudes for more that 700 stars having no previous photometric data. New spectroscopic and photometric results as well as previous photoelectric UBV values are given in the catalogue together with additional remarks concerning peculiarities of spectra, V magnitudes, and details on double and multiple systems.
- ID:
- ivo://CDS.VizieR/J/ApJ/810/116
- Title:
- S-type AGB stars in SMC
- Short Name:
- J/ApJ/810/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified a new class of Asymptotic Giant Branch (AGB) stars in the Small and Large Magellanic Clouds (SMC/LMC) using optical to infrared photometry, light curves, and optical spectroscopy. The strong dust production and long-period pulsations of these stars indicate that they are at the very end of their AGB evolution. Period-mass-radius relations for the fundamental-mode pulsators give median current stellar masses of 1.14M_{sun}_ in the LMC and 0.94M_{sun}_ in the SMC (with dispersions of 0.21 and 0.18M_{sun}_, respectively), and models suggest initial masses of <1.5M_{sun}_ and <1.25 M_{sun}_, respectively. This new class of stars includes both O-rich and C-rich chemistries, placing the limit where dredge-up allows carbon star production below these masses. A high fraction of the brightest among them should show S star characteristics indicative of atmospheric C/O~1, and many will form O-rich dust prior to their C-rich phase. These stars can be separated from their less-evolved counterparts by their characteristically red J-[8] colors.
540. SUMaC I
- ID:
- ivo://CDS.VizieR/J/MNRAS/466/4540
- Title:
- SUMaC I
- Short Name:
- J/MNRAS/466/4540
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from the Swift Ultraviolet Survey of the Magellanic Clouds, the highest resolution ultraviolet (UV) survey of the Magellanic Clouds yet completed. In this paper, we focus on the Small Magellanic Cloud (SMC). When combined with multiwavelength optical and infrared observations, the three near-UV filters on the Swift Ultraviolet/Optical Telescope are conducive to measuring the shape of the dust extinction curve and the strength of the 2175{AA} dust bump. We divide the SMC into UV-detected star-forming regions and large 200-arcsec (58pc) pixels and then model the spectral energy distributions using a Markov-chain Monte Carlo method to constrain the ages, masses, and dust curve properties. We find that the majority of the SMC has a 2175{AA} dust bump, which is larger to the north-east and smaller to the south-west, and that the extinction curve is predominantly steeper than the Galactic curve. We also derive a star formation history and find evidence for peaks in the star formation rate at 6-10, 30-80, and 400Myr, the latter two of which are consistent with previous work.
