scholarly journals The VMC survey – XXXVI. Young stellar variability in the Large Magellanic Cloud

2020 ◽  
Vol 494 (1) ◽  
pp. 458-486 ◽  
Author(s):  
Viktor Zivkov ◽  
Joana M Oliveira ◽  
Monika G Petr-Gotzens ◽  
Stefano Rubele ◽  
Maria-Rosa L Cioni ◽  
...  
Keyword(s):  
Near Infrared ◽  
High Reliability ◽  
Large Magellanic Cloud ◽  
Systematic Investigation ◽  
Variable Stars ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Light Curves ◽  
Young Stellar Objects ◽  
Photometric Variability

ABSTRACT Studies of young stellar objects (YSOs) in the Galaxy have found that a significant fraction exhibits photometric variability. However, no systematic investigation has been conducted on the variability of extragalactic YSOs. Here we present the first variability study of massive YSOs in an $\sim 1.5\, \mathrm{deg^2}$ region of the Large Magellanic Cloud (LMC). The aim is to investigate whether the different environmental conditions in the metal-poor LMC ($\sim 0.4\!-\!0.5\, \mathrm{Z_{\odot }}$) have an impact on the variability characteristics. Multi-epoch near-infrared (NIR) photometry was obtained from the VISTA Survey of the Magellanic Clouds (VMC) and our own monitoring campaign using the VISTA telescope. By applying a reduced χ2-analysis, stellar variability was identified. We found 3062 candidate variable stars from a population of 362 425 stars detected. Based on several Spitzer studies, we compiled a sample of high-reliability massive YSOs: a total of 173 massive YSOs have NIR counterparts (down to $K_s\sim 18.5\,$mag) in the VMC catalogue, of which 39 display significant (>3σ) variability. They have been classified as eruptive, fader, dipper, short-term variable, and long-period variable YSOs based mostly on the appearance of their Ks-band light curves. The majority of YSOs are aperiodic; only five YSOs exhibit periodic light curves. The observed amplitudes are comparable or smaller than those for Galactic YSOs (only two Magellanic YSOs exhibit $\Delta K_s\gt 1\,$mag), not what would have been expected from the typically larger mass accretion rates observed in the Magellanic Clouds.

scholarly journals The Characteristics of the Field RR Lyrae Stars in the Magellanic Clouds

1974 ◽  
Vol 59 ◽  
pp. 107-108
Author(s):  
J. A. Graham
Keyword(s):  
Stellar Evolution ◽  
Large Magellanic Cloud ◽  
Variable Stars ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Light Curves ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
First Results ◽  
Lyrae Stars

The Magellanic Clouds are well known as being very suitable for observing the various stages of stellar evolution. During the last few years, I have been studying the RR Lyrae variable stars in each of the two Clouds. Some first results were reported at IAU Colloquium No. 21 in 1972 (Graham, 1973). Here, I would like to update these results on the basis of more recent data and to comment on some of the characteristics of the field RR Lyrae stars in each system. Periods and light curves are now available for 63 RR Lyrae stars in a 1° x 1.3° field centered on the cluster NGC 1783 in the Large Magellanic Cloud (LMC) and for 62 stars in a 1° x 1.3° field centered on the cluster NGC 121 in the Small Magellanic Cloud (SMC). Both ab and c type variables are represented and, viewed individually, the Cloud RR Lyraes are identical in characteristics to those known in our Galaxy. Studied as groups, however, there are small but significant differences between the RR Lyrae stars in each system. The following four specific features seem to be emerging from the study.

scholarly journals Spectroscopy of Overluminous Cepheids in the Magellanic Clouds

1984 ◽  
Vol 108 ◽  
pp. 223-224
Author(s):  
Horace A. Smith ◽  
Leo Connolly
Keyword(s):  
Globular Cluster ◽  
Large Magellanic Cloud ◽  
Variable Stars ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Small Magellanic Cloud ◽  
Single Star ◽  
Rr Lyrae ◽  
Short Period ◽  
The Galaxy

The Small Magellanic Cloud is known to contain types of short period Cepheid variable stars not yet discovered in either the Large Magellanic Cloud or, with the exception of a single star, in the Galaxy. These variables can be divided into two categories: anomalous Cepheids and Wesselink-Shuttleworth (WS) stars. The former, which have also been found in dwarf spheroidal systems and in the globular cluster NGC 5466, have periods of 0.4–3 days, but average 0.7–1.0 mag. brighter than RR Lyrae and BL Her stars of equal period. The stars we call WS stars have periods less than about 1.1 day and, at MV = −1 to −2, are brighter than anomalous Cepheids of equal period.

scholarly journals First CCD observations of Magellanic Cloud variable stars from the Mt John University Observatory, New Zealand

1991 ◽  
Vol 148 ◽  
pp. 381-381
Author(s):  
William Tobin ◽  
A. C. Gilmore ◽  
Alan Wadsworth ◽  
S.R.D. West
Keyword(s):  
New Zealand ◽  
Evaluation Process ◽  
Variable Stars ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Eclipsing Binaries ◽  
Light Curves ◽  
Ccd Observations ◽  
Differential Photometry

Late in 1988 the Mt John University Observatory acquired a cryogenic CCD system from Photometrics Ltd (Tucson). The chip is a Thomson CSF TH7882 CDA comprising 384 × 576 pixels. As part of the evaluation process, we have begun two differential photometry programs of the Magellanic Clouds using the Mt John 0.6m Boller & Chivens telescope. On this telescope each CCD pixel corresponds to 0.6 arcsec. Mt John's southerly latitude (44°S) permits year-round observations of the Clouds.The first program concerns B, V and I photometry of five blue eclipsing binaries selected, on the basis of Gaposchkin's (1970, 1977) photographic light curves, to have roughly equal components with minimal interaction. HV 12634 has also been observed for comparison with the CCD light curves published by Jensen et al. (1988). Fig. 1 shows the B observations so far obtained for HV 1761, but the reduction is preliminary, being based on aperture-integrated magnitudes. The field is populous, and a final reduction will require use of a crowded-field reduction package such as ROMAFOT.

scholarly journals AKARI Near-Infrared Spectroscopy: Detection of H 2 O and CO 2 Ices toward Young Stellar Objects in the Large Magellanic Cloud

2008 ◽  
Vol 686 (2) ◽  
pp. L99-L102 ◽  
Author(s):  
Takashi Shimonishi ◽  
Takashi Onaka ◽  
Daisuke Kato ◽  
Itsuki Sakon ◽  
Yoshifusa Ita ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Young Stellar Objects ◽  
Stellar Objects

scholarly journals Planetary nebulae in the VISTA Magellanic Cloud (VMC) Survey

2011 ◽  
Vol 7 (S283) ◽  
pp. 444-445
Author(s):  
Brent Miszalski ◽  
Ralph Napiwotzki ◽  
Maria-Rosa L. Cioni ◽  
Martin A. T. Groenewegen ◽  
Jose M. Oliveira ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Near Infrared ◽  
Planetary Nebulae ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
First Year ◽  
Complementary Role ◽  
Initial Results ◽  
Central Stars

AbstractThe multi-epoch YJKs sub-arcsecond photometry of the VMC survey provides a long anticipated deep near-infrared (NIR) window into further understanding the stellar populations of the Magellanic Clouds. The first year of observations consisted of six tiles covering ~9% of the Large Magellanic Cloud (LMC) survey region and contains 102 objects previously classified as planetary nebulae (PNe). A large proportion of the sample were found to be contaminated by non-PNe. These initial results underline the importance of establishing a clean catalogue of LMC PNe before they are applied in areas such as the planetary nebula luminosity function (PNLF) and searches for binary central stars. As the VMC survey progresses it will play a fundamental role in cleaning extant PN catalogues and a complementary role in the discovery of new PNe.

scholarly journals AKARI near-infrared spectroscopy: Detection of H2O and CO2 ices toward young stellar objects in the Large Magellanic Cloud

2008 ◽  
Vol 4 (S256) ◽  
pp. 233-238
Author(s):  
Takashi Shimonishi ◽  
Takashi Onaka ◽  
Daisuke Kato ◽  
Itsuki Sakon ◽  
Yoshifusa Ita ◽  
...  
Keyword(s):  
Radiation Field ◽  
Near Infrared ◽  
Infrared Camera ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Chemical Balance ◽  
Circumstellar Material ◽  
Growth Method

AbstractWe present the first results of the AKARI Infrared Camera near-infrared spectroscopic survey of the Large Magellanic Cloud (LMC). The circumstellar material of young stellar objects (YSOs) are affected by galactic environments such as a metallicity or radiation field. Ices control the chemical balance of circumstellar environments of embedded YSOs. We detected absorption features of the H2O ice 3.05 μm and the CO2 ice 4.27 μm stretching mode toward seven massive YSOs in the LMC. This is the first detection of the 4.27 μm CO2 ice feature toward extragalactic YSOs. The present samples are for the first time spectroscopically confirmed to be YSOs. We used a curve-of-growth method to evaluate the column densities of the ices and derived the CO2/H2O ratio to be 0.45±0.17. This is clearly higher than that seen in Galactic massive YSOs (0.17±0.03). We suggest that the strong ultraviolet radiation field and/or the high dust temperature in the LMC may be responsible for the observed high CO2 ice abundance.

scholarly journals IRSF/SIRIUS near-infrared survey of the Magellanic Clouds: triggered star formation in N11 in the Large Magellanic Cloud

2006 ◽  
Vol 2 (S237) ◽  
pp. 423-423
Author(s):  
H. Hatano ◽  
R. Kadowaki ◽  
D. Kato ◽  
S. Sato ◽  
Keyword(s):  
Star Formation ◽  
Near Infrared ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Infrared Survey

AbstractA near-infrared survey of the Magellanic Clouds has been carried out with IRSF/SIRIUS. As a part of the results, we present a study of triggered star formation in N11 in the LMC.

scholarly journals The study of unclassified B[e] stars and candidates in the Galaxy and Magellanic Clouds†

2019 ◽  
Vol 488 (1) ◽  
pp. 1090-1110 ◽  
Author(s):  
C A H Condori ◽  
M Borges Fernandes ◽  
M Kraus ◽  
D Panoglou ◽  
C A Guerrero
Keyword(s):  
Main Sequence ◽  
Interstellar Extinction ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Light Curves ◽  
Evolutionary Stage ◽  
The Third ◽  
The Galaxy ◽  
Gaia Dr2

ABSTRACT We investigated 12 unclassified B[e] stars or candidates, 8 from the Galaxy, 2 from the Large Magellanic Cloud (LMC), and 2 from the Small Magellanic Cloud (SMC). Based on the analysis of high-resolution spectroscopic (FEROS) and photometric data, we confirmed the presence of the B[e] phenomenon for all objects of our sample, except for one (IRAS 07455-3143). We derived their effective temperature, spectral type, luminosity class, interstellar extinction and, using the distances from Gaia DR2, we obtained their bolometric magnitude, luminosity, and radius. Modelling of the forbidden lines present in the FEROS spectra revealed information about the kinematics and geometry of the circumstellar medium of these objects. In addition, we analysed the light curves of four stars, finding their most probable periods. The evolutionary stage of 11 stars of our sample is suggested from their position on the HR diagram, taking into account evolutionary tracks of stars with solar, LMC, and SMC metallicities. As results, we identified B and B[e] supergiants, B[e] stars probably at the main sequence or close to its end, post-AGB and HAeB[e] candidates, and A[e] stars in the main sequence or in the pre-main sequence. However, our most remarkable results are the identification of the third A[e] supergiant (ARDB 54, the first one in the LMC), and of an ‘LBV impostor’ in the SMC (LHA 115-N82).

scholarly journals Characterising the Protostellar Population of the Magellanic Clouds with VLT/SINFONI

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Jacob Ward ◽  
Joana Oliveira ◽  
Jacco van Loon ◽  
Marta Sewilo
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Emission Lines ◽  
Young Stellar Objects ◽  
Small Magellanic Cloud ◽  
Stellar Objects ◽  
Accretion Rates

AbstractAt distances of ~50 kpc and ~60 kpc for the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) respectively the Magellanic Clouds present us with a unique opportunity to study star formation in environments outside our own galaxy. Through Spitzer and Herschel photometry and spectroscopy, samples of Young Stellar Objects (YSOs) have been selected and spectroscpically confirmed in the Magellanic Clouds. Here we present some of the key results of our SINFONI K-band observations towards massive YSOs in the Magellanic Clouds. We resolve a number of Spitzer sources into multiple, previously unresolved, components and our analysis of emission lines suggest higher accretion rates and different disc properties compared with massive YSOs in the Milky Way.

New Cepheid Period-Luminosity Relations for the Large Magellanic Cloud: 92 Near-Infrared Light Curves

2004 ◽  
Vol 128 (5) ◽  
pp. 2239-2264 ◽  
Author(s):  
S. E. Persson ◽  
Barry F. Madore ◽  
W. Krzemiński ◽  
Wendy L. Freedman ◽  
M. Roth ◽  
...  
Keyword(s):  
Near Infrared ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Infrared Light ◽  
Near Infrared Light
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