- ID:
- ivo://CDS.VizieR/J/A+A/456/451
- Title:
- Magellanic Clouds PNe abundances
- Short Name:
- J/A+A/456/451
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second part of an optical spectroscopic study of planetary nebulae in the LMC and SMC. The first paper, Leisy & Dennefeld (1996, Cat. <J/A+AS/116/95>), discussed the CNO cycle for those objects where C abundances were available. In this paper we concentrate more on other elemental abundances (such as O, Ne, S, Ar) and their implications for the evolution of the progenitor stars. We use a much larger sample of 183 objects, of which 65 are our own observations, where the abundances have been re-derived in a homogeneous way. For 156 of them, the quality of data is considered to be satisfactory for further analysis.
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- ID:
- ivo://CDS.VizieR/J/A+AS/116/95
- Title:
- Magellanic Clouds PNe line intensities
- Short Name:
- J/A+AS/116/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical and ultraviolet spectroscopic observations of planetary nebulae (PNe) in the Large (LMC) and the Small Magellanic Clouds (SMC). For the visible spectra with highest S/N, line intensities have been measured to a few tenths of a percent of H_{beta}_. UV spectra are used for the determination of carbon abundances. This paper discusses the CNO cycle and its implications. We show that the CN or ON cycles are more effective with lower initial metallicities and are always complete for typeI nebulae. The latter cannot easily be distinguished from non-type I PNe on the basis of N or He abundance alone, as continuity exists in all of the standard diagrams. From the study of the C abundances, we deduce that the 3rd dredge-up is occurring in all PNe: its efficiency too is higher with lower initial metallicities, offering an easy explanation for the higher number of carbon stars found in metal-deficient galaxies. It is shown that this dredged-up carbon is sometimes transformed into nitrogen by Hot-Bottom Burning, but in a few objects only and not even in all the typeI PNe, which therefore do not form a homogeneous class.
- ID:
- ivo://CDS.VizieR/J/A+A/628/A51
- Title:
- Magellanic Clouds reddening map
- Short Name:
- J/A+A/628/A51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The reddening maps of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) are constructed using the Cepheid period-luminosity (P-L) relations. We examine reddening distribution across the LMC and SMC through large data sets on classical Cepheids provided by the OGLE Phase IV survey. We also investigate the age and spatio-temporal distributions of Cepheids to understand the recent star formation history in the LMC and SMC. The V and I band photometric data of 2476 fundamental mode (FU) and 1775 first overtone mode (FO) Cepheids in the LMC, and 2753 FU and 1793 FO Cepheids in the SMC were analysed for their P-L relations. We converted the period of FO Cepheids to the corresponding period of FU Cepheids before combining the two modes of Cepheids. Both galaxies were divided into small segments and combined FU and FO P-L diagrams were drawn in two bands for each segment. The reddening analysis was performed on 133 segments covering a total area of about 154.6deg^2^ in the LMC and 136 segments covering a total area of about 31.3deg^2^ in the SMC. By comparison with well-calibrated P-L relations of these two galaxies, we determined reddening E(V-I) in each segment and equivalent reddening E(B-V) assuming the normal extinction law. The period-age relations were used to derive the age of the Cepheids. Reddening maps were constructed using reddening values in different segments across the LMC and SMC. We find clumpy structures in the reddening distributions of the LMC and SMC. From the reddening map of the LMC, highest reddening of E(V-I)=0.466mag is traced in the region centred at RA~85.13deg, DEC~-69.34deg which is in close vicinity of the star forming HII region 30 Doradus. In the SMC, maximum reddening of E(V-I)=0.189mag is detected in the region centred at RA~12.10deg, DEC~-73.07deg. The mean reddening values in the LMC and SMC are estimated as E(V-I)_LMC_=0.113+/-0.060mag, E(B-V)_LMC_=0.091+/-0.050mag, E(V-I)_SMC_=0.049+/-0.070mag, and E(B-V)_SMC_=0.038+/-0.053mag. The LMC reddening map displays heterogeneous distribution having small reddening in the central region and higher reddening towards the eastern side of the LMC bar. The SMC has relatively small reddening in its peripheral regions but larger reddening towards the south-west region. In these galaxies, we see evidence of a common enhanced Cepheid population at around 200 Myr ago which appears to have occurred due to a close encounter between the two clouds.
- ID:
- ivo://CDS.VizieR/J/AJ/116/180
- Title:
- Magellanic clouds ultraviolet observations
- Short Name:
- J/AJ/116/180
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog is derived from wide-field far-ultraviolet (FUV; 1300-1800{AA}) images of the Large and Small Magellanic Clouds (LMC, SMC) obtained by the Ultraviolet Imaging Telescope (UIT) during the Astro-1 (1990 December 1-10) and Astro-2 (1995 March 2-18) missions. The FUV magnitudes are derived from point-spread function photometry for 37,333 stars in the LMC (the UIT FUV magnitudes for 11,306 stars in the SMC were presented by Cornett et al. (1997AJ....113.1011C), with a completeness limit of m_UV_ ~ 15mag and a detection limit of m_UV_ ~ 17.5. The average uncertainty in the photometry is ~ 0.1mag.
- ID:
- ivo://CDS.VizieR/J/MNRAS/471/4571
- Title:
- Magellanic Inter-Cloud Project. III
- Short Name:
- J/MNRAS/471/4571
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Magellanic Bridge (MB) is a gaseous stream that links the Large (LMC) and Small (SMC) Magellanic Clouds. Current simulations suggest that the MB forms from a recent interaction between the Clouds. In this scenario, the MB should also have an associated stellar bridge formed by stars tidally stripped from the SMC by the LMC. There are several observational evidences for these stripped stars, from the presence of intermediate age populations in the MB and carbon stars, to the recent observation of an over-density of RR Lyrae stars offset from the MB. However, spectroscopic confirmation of stripped stars in the MB remains lacking. In this paper, we use medium resolution spectra to derive the radial velocities and metallicities of stars in two fields along the MB. We show from both their chemistry and kinematics that the bulk of these stars must have been tidally stripped from the SMC. This is the first spectroscopic evidence for a dwarf galaxy being
- ID:
- ivo://CDS.VizieR/J/ApJ/746/27
- Title:
- Magellanic Quasars Survey. II. AGNs behind LMC
- Short Name:
- J/ApJ/746/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We quadruple the number of quasars known behind the Large Magellanic Cloud (LMC) from 56 (42 in the Optical Gravitational Lensing Experiment (OGLE)-III LMC fields) to 200 by spectroscopically confirming 169 (144 new) quasars from a sample of 845 observed candidates in four ~3 deg^2^ Anglo-Australian Telescope/AAOmega fields south of the LMC center. The candidates were selected based on their Spitzer mid-infrared colors, X-ray emission, and/or optical variability properties in the database of the OGLE microlensing survey. The contaminating sources can be divided into 115 young stellar objects (YSOs), 17 planetary nebulae (PNe), 39 Be and 24 blue stars, 68 red stars, and 12 objects classed as either YSO/PN or blue star/YSO. There are also 402 targets with either featureless spectra or too low signal-to-noise ratios for source classification. Our quasar sample is 50% (30%) complete at I = 18.6 mag (19.3 mag). The newly discovered active galactic nuclei (AGNs) provide many additional reference points for proper motion studies of the LMC, and the sample includes 10 bright AGNs (I < 18 mag) that are potentially suitable for absorption line studies. Their primary use, however, is for detailed studies of quasar variability, as they all have long-term, high cadence, continuously growing light curves from the microlensing surveys of the LMC. Completing the existing Magellanic Quasars Survey fields in the LMC and Small Magellanic Cloud should yield a sample of ~700 well-monitored AGNs, and expanding it to the larger regions covered by the OGLE-IV survey should yield a sample of ~3600 AGNs.
- ID:
- ivo://CDS.VizieR/J/ApJS/194/22
- Title:
- Magellanic Quasars Survey: QSOs behind SMC
- Short Name:
- J/ApJS/194/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the spectroscopic confirmation of 29 new, 12 plausible, and three previously known quasars behind the central ~1.5deg^2^ region of the Small Magellanic Cloud (SMC). These were identified in a single 2df/AAOmega observation on the Anglo-Australian Telescope of 268 candidates selected primarily based on their mid-IR colors, along with a smaller number of optically variable sources in OGLE-II close to known X-ray sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/611/270
- Title:
- Magellanic star clusters IR fluctuations
- Short Name:
- J/ApJ/611/270
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present surface brightness fluctuations (SBFs) in the near-IR for 191 Magellanic star clusters available in the Second Incremental and All Sky Data releases of the Two Micron All Sky Survey (2MASS, Cat. <II/246>) and compare them with SBFs of Fornax Cluster galaxies and with predictions from stellar population models as well.
- ID:
- ivo://CDS.VizieR/J/ApJ/688/1029
- Title:
- Magnetic field in the SMC
- Short Name:
- J/ApJ/688/1029
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the magnetic field of the Small Magellanic Cloud (SMC), carried out using radio Faraday rotation and optical starlight polarization data. Consistent negative rotation measures (RMs) across the SMC indicate that the line-of-sight magnetic field is directed uniformly away from us with a strength 0.19+/-0.06{mu}G. Applying the Chandrasekhar-Fermi method to starlight polarization data yields an ordered magnetic field in the plane of the sky of strength 1.6+/-0.4uG oriented at a position angle 4+/-12{deg}, measured counterclockwise from the great circle on the sky joining the SMC to the Large Magellanic Cloud (LMC). We construct a three-dimensional magnetic field model of the SMC, under the assumption that the RMs and starlight polarization probe the same underlying large-scale field. further test the pan-Magellanic field hypothesis.
- ID:
- ivo://CDS.VizieR/J/ApJ/875/51
- Title:
- Mass accretion rates of PMS stars. VI. LH95 in LMC
- Short Name:
- J/ApJ/875/51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the accretion properties of low-mass stars in the LH 95 association within the Large Magellanic Cloud. Using noncontemporaneous wideband optical and narrowband H{alpha} photometry obtained with the Hubble Space Telescope, we identify 245 low-mass pre-main-sequence (PMS) candidates showing H{alpha} excess emission above the 4{sigma} level. We derive their physical parameters, including effective temperatures, luminosities, masses (M_*_), ages, accretion luminosities, and mass accretion rates (dM/dt_acc_). We identify two different stellar populations: younger than ~8Myr with median dM/dt_acc_~5.4x10^-8^M_{sun}_/yr (and M_*_~0.15-1.8M_{sun}_) and older than ~8Myr with median dM/dt_acc_~4.8x10^-9^M_{sun}_/yr (and M_*_~0.6-1.2M_{sun}_). We find that the younger PMS candidates are assembled in groups around Be stars, while older PMS candidates are uniformly distributed within the region without evidence of clustering. We find that dM/dt_acc_ in LH 95 decreases with time more slowly than what is observed in Galactic star-forming regions (SFRs). This agrees with the recent interpretation, according to which higher metallicity limits the accretion process in both rate and duration due to higher radiation pressure. The dM/dt_acc_-M_*_ relationship shows different behavior at different ages, becoming progressively steeper at older ages, indicating that the effects of mass and age on dM/dt_acc_ cannot be treated independently. With the aim to identify reliable correlations between mass, age, and dM/dt_acc_, we used a multivariate linear regression fit between these parameters for our PMS candidates. The comparison between our results and those obtained in other SFRs of our Galaxy and the Magellanic Clouds confirms the importance of the metallicity for the study of the dM/dt_acc_ evolution in clusters with different environmental conditions.
