Detailed chemical composition of classical Cepheids in the LMC cluster NGC 1866 and in the field of the SMC

Context. Cepheids are excellent tracers of young stellar populations. They play a crucial role in astrophysics as standard candles. The chemistry of classical Cepheids in the Milky Way is now quite well-known, however despite a much larger sample, the chemical composition of Magellanic Cepheids has been only scarcely investigated. Aims. For the first time, we study the chemical composition of several Cepheids located in the same populous cluster: NGC 1866, in the Large Magellanic Cloud (LMC). To also investigate the chemical composition of Cepheids at lower metallicity, we look at four targets located in the Small Magellanic Cloud (SMC). Our sample allows us to increase the number of Cepheids with known metallicities in the LMC/SMC by 20%/25% and the number of Cepheids with detailed chemical composition in the LMC/SMC by 46%/50%. Methods. We use canonical spectroscopic analysis to determine the chemical composition of Cepheids and provide abundances for a good number of α, iron-peak, and neutron-capture elements. Results. We find that six Cepheids in the LMC cluster NGC 1866 have a very homogeneous chemical composition, also consistent with red giant branch (RGB) stars in the cluster. Period–age relations that include no or average rotation indicate that all the Cepheids in NGC 1866 have a similar age and therefore belong to the same stellar population. Our results are in good agreement with theoretical models accounting for luminosity and radial velocity variations. Using distances based on period-luminosity relations in the near- or mid-infrared, we investigate for the first time the metallicity distribution of the young population in the SMC in the depth direction. Preliminary results show no metallicity gradient along the SMC main body, but our sample is small and does not contain Cepheids in the inner few degrees of the SMC.

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The MAGIC project – II. Discovery of two new Galactic lithium-rich Cepheids

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1872 ◽

2019 ◽

Vol 488 (3) ◽

pp. 3211-3221

Author(s):

V Kovtyukh ◽

B Lemasle ◽

A Kniazev ◽

L Berdnikov ◽

G Bono ◽

...

Keyword(s):

Chemical Composition ◽

Mixed Mode ◽

Milky Way ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Large Telescope ◽

Instability Strip ◽

Red Giant ◽

First Time

Abstract We report the discovery of two new lithium-rich Cepheids in the Milky Way (A(Li) ≈ 2.9 dex) among the targets of the MAGIC spectroscopic survey with the Southern African Large Telescope spectrographs. The 6707 Å Li feature is usually not detectable in the atmosphere of Cepheids. Only three Cepheids (two in the Milky Way and one in the Large Magellanic Cloud) had been reported so far with high lithium abundances. We examine the possibility that the Li-rich Cepheids are evolving towards the red giant branch, crossing the instability strip for the first time, as well as other possible scenarios. The two stars are mixed-mode Cepheids pulsating simultaneously in the first and in the second overtone modes. We briefly discuss the possible connection between their unusual chemical composition and their pulsational properties.

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CCD SDSS gr Photometry of Poorly Studied Star Clusters in the Large Magellanic Cloud

ISRN Astronomy and Astrophysics ◽

10.1155/2014/398182 ◽

2014 ◽

Vol 2014 ◽

pp. 1-12

Author(s):

Andrés E. Piatti

Keyword(s):

Metal Content ◽

Star Clusters ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Main Body ◽

Field Star ◽

Subtraction Procedure ◽

Radial Profiles ◽

First Time ◽

Stellar Density

We present for the first time CCD SDSS gr photometry, obtained at the Gemini South telescope with the GMOS attached, of stars in the field of the poorly studied star clusters NGC1768, HS 85, SL 676, NGC2107, NGC2190, and SL 866, which are distributed in the main body of the Large Magellanic Cloud. We applied a subtraction procedure to statistically clean the cluster CMDs from field star contamination. In order to disentangle cluster features from those belonging to their surrounding fields, we applied a subtraction procedure which makes use of variable cells to reproduce the field star color-magnitude diagrams (CMDs) as closely as possible. We then traced their stellar density radial profiles from star counts performed over the cleaned field stars dataset and derived their radii. Using the cleaned cluster CMDs, we estimated ages and metallicities from matching theoretical isochrones computed for the SDSS system. The studied star clusters have ages from 0.1 up to 2.0 Gyr and are of slightly metal-poor metal content ([Fe/H]≈−0.4 dex).

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Molecules in the Magellanic Clouds

Symposium - International Astronomical Union ◽

10.1017/s0074180900201046 ◽

1991 ◽

Vol 148 ◽

pp. 415-420 ◽

Cited By ~ 1

Author(s):

R. S. Booth ◽

Th. De Graauw

Keyword(s):

High Resolution ◽

Molecular Clouds ◽

Short Review ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Magellanic Clouds ◽

Giant Molecular Clouds ◽

Interstellar Molecules ◽

First Time ◽

Excitation Conditions

In this short review we describe recent new observations of millimetre transitions of molecules in selected regions of the Magellanic Clouds. The observations were made using the Swedish-ESO Submillimetre Telescope, SEST, (Booth et al. 1989), the relatively high resolution of which facilitates, for the first time, observations of individual giant molecular clouds in the Magellanic Clouds. We have mapped the distribution of the emission from the two lowest rotational transitions of 12CO and 13CO and hence have derived excitation conditions for the molecule. In addition, we have observed several well-known interstellar molecules in the same regions, thus doubling the number of known molecules in the Large Magellanic Cloud (LMC). The fact that all the observations have been made under controlled conditions with the same telescope enables a reasonable intercomparison of the molecular column densities. In particular, we are able to observe the relative abundances among the different isotopically substituted species of CO.

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Line observations of the 30-Dor complex and N159A5 with the MPE imaging NIR spectrometer FAST

Symposium - International Astronomical Union ◽

10.1017/s0074180900200375 ◽

1991 ◽

Vol 148 ◽

pp. 205-206 ◽

Cited By ~ 1

Author(s):

A. Krabbe ◽

J. Storey ◽

V. Rotaciuc ◽

S. Drapatz ◽

R. Genzel

Keyword(s):

Spatial Resolution ◽

Molecular Hydrogen ◽

Near Infrared ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Emission Lines ◽

Resolving Power ◽

Max Planck ◽

First Time ◽

Infrared Array

Images with subarcsec spatial resolution in the light of near-infrared atomic (Bry) and molecular hydrogen H2 (S(1) v=1-0) emission lines were obtained for some extended, pointlike objects in the Large Magellanic Cloud (LMC) for the first time. We used the Max-Planck-Institut für extraterrestrische Physik (MPE) near-infrared array spectrometer FAST (image scale 0.8”/pix, spectral resolving power 950) at the ESO/MPI 2.2m telescope, La Silla. We present some results on the 30-Dor complex and N159A5.

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New optically identified supernova remnants in the Large Magellanic Cloud

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3382 ◽

2020 ◽

Vol 500 (2) ◽

pp. 2336-2358

Author(s):

Miranda Yew ◽

Miroslav D Filipović ◽

Milorad Stupar ◽

Sean D Points ◽

Manami Sasaki ◽

...

Keyword(s):

Supernova Remnants ◽

Supernova Remnant ◽

Narrow Band Imaging ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Main Body ◽

Found Objects ◽

Type Ia ◽

Optical Sample

ABSTRACT We present a new optical sample of three Supernova Remnants (SNRs) and 16 Supernova Remnant (SNR) candidates in the Large Magellanic Cloud (LMC). These objects were originally selected using deep H α, [S ii], and [O iii] narrow-band imaging. Most of the newly found objects are located in less dense regions, near or around the edges of the LMC’s main body. Together with previously suggested MCSNR J0541–6659, we confirm the SNR nature for two additional new objects: MCSNR J0522–6740 and MCSNR J0542–7104. Spectroscopic follow-up observations for 12 of the LMC objects confirm high [S ii]/H α emission-line ratios ranging from 0.5 to 1.1. We consider the candidate J0509–6402 to be a special example of the remnant of a possible type Ia Supernova (SN) which is situated some 2° (∼1.75 kpc) north from the main body of the LMC. We also find that the SNR candidates in our sample are significantly larger in size than the currently known LMC SNRs by a factor of ∼2. This could potentially imply that we are discovering a previously unknown but predicted, older class of large LMC SNRs that are only visible optically. Finally, we suggest that most of these LMC SNRs are residing in a very rarefied environment towards the end of their evolutionary span where they become less visible to radio and X-ray telescopes.

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THE PANCHROMATIC VIEW OF THE MAGELLANIC CLOUDS FROM CLASSICAL CEPHEIDS. I. DISTANCE, REDDENING, AND GEOMETRY OF THE LARGE MAGELLANIC CLOUD DISK

The Astrophysical Journal ◽

10.3847/0004-637x/832/2/176 ◽

2016 ◽

Vol 832 (2) ◽

pp. 176 ◽

Cited By ~ 42

Author(s):

L. Inno ◽

G. Bono ◽

N. Matsunaga ◽

G. Fiorentino ◽

M. Marconi ◽

...

Keyword(s):

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Magellanic Clouds ◽

Classical Cepheids

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Properties of two star clusters of the LMC: NGC 2164, NGC 1850

Symposium - International Astronomical Union ◽

10.1017/s0074180900200442 ◽

1991 ◽

Vol 148 ◽

pp. 219-221

Author(s):

A. Vallenari ◽

C. Chiosi ◽

G. Bertelli ◽

G. Meylan ◽

S. Ortolani

Keyword(s):

Star Clusters ◽

Theoretical Models ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Luminosity Functions ◽

Stellar Models ◽

Convective Overshoot

We present the photometry of two clusters NGC 2164 and NGC 1850 located in the Large Magellanic Cloud (LMC). The ages are determined taking into account the presence either of convective overshoot or of semiconvection in the stellar models. The experimental luminosity functions are compared with the theoretical models.

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ULTRA-LOW AMPLITUDE VARIABLES IN THE LARGE MAGELLANIC CLOUD—CLASSICAL CEPHEIDS, POP. II CEPHEIDS, RV TAU STARS, AND BINARY VARIABLES

The Astrophysical Journal ◽

10.1088/0004-637x/698/1/944 ◽

2009 ◽

Vol 698 (1) ◽

pp. 944-955 ◽

Cited By ~ 7

Author(s):

J. Robert Buchler ◽

Peter R. Wood ◽

Igor Soszyński

Keyword(s):

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Binary Variables ◽

Classical Cepheids ◽

Rv Tau Stars ◽

Low Amplitude

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Period–luminosity–metallicity relation of classical Cepheids

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038714 ◽

2020 ◽

Vol 642 ◽

pp. A230

Author(s):

V. Ripepi ◽

G. Catanzaro ◽

R. Molinaro ◽

M. Marconi ◽

G. Clementini ◽

...

Keyword(s):

Near Infrared ◽

Data Gathering ◽

Hubble Constant ◽

Zero Point ◽

Total Sample ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Point Of View ◽

Classical Cepheids ◽

Metal Abundance

Context. Classical Cepheids (DCEPs) are the most important primary indicators for the extragalactic distance scale. Establishing the dependence on metallicity of their period–luminosity and period–Wesenheit (PL and PW) relations has deep consequences for the estimate of the Hubble constant (H0). Aims. We investigate the dependence on metal abundance ([Fe/H]) of the PL and PW relations for Galactic DCEPs. Methods. We combined proprietary and literature photometric and spectroscopic data, gathering a total sample of 413 Galactic DCEPs (372 fundamental mode, DCEP_F, and 41 first-overtone, DCEP_1O) and constructed new metallicity-dependent PL and PW relations in the near-infrared adopting the astrometry-based luminosity. Results. We find indications that the slopes of the PL(KS) and PW(J, KS) relations for Galactic DCEPs might depend on metallicity on the basis of the comparison with the Large Magellanic Cloud relationships. Therefore we used a generalized form of the PL and PW relations to simultaneously take the metallicity dependence of the slope and intercept of these relations into account. Conclusions. We calculated PL and PW relations that for the first time explicitly include a metallicity dependence of the slope and intercept terms. The quality of the available data is insufficient, however, and we cannot yet present conclusive results, but they are relevant from a methodological point of view. The new relations are linked to the geometric measurement of the distance to the Large Magellanic Cloud and allowed us to estimate a Gaia DR2 parallax zero-point offset Δϖ = 0.0615 ± 0.004 mas from the dataset of DCEPs used in this work.

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