scholarly journals Ultra-Short Period Cepheids in the LMC

1980 ◽  
Vol 58 ◽  
pp. 443-448
Author(s):  
Leo Connolly
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Instability Strip ◽  
Additional Variable ◽  
Short Period

Six Cepheids in the Large Magellanic Cloud have been discovered with periods less than one day. They lie at the faint, blue end of the instability strip as would be expected but form a separate Period-Luminosity relation from that for normal Cepheids. Membership in the LMC is based upon the existence of the P-L relationship. Several of the variables have uncertain periods although all apparently have periods under one day. One additional variable has tentatively been identified as a bright Anomalous Cepheid.

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 Erratum: Candidates for non-pulsating stars located in the Cepheid instability strip in the Large Magellanic Cloud based on Strömgren photometry

2019 ◽  
Vol 491 (2) ◽  
pp. 2770-2770
Author(s):  
Weronika Narloch ◽  
G Pietrzyński ◽  
Z Kołaczkowski ◽  
R Smolec ◽  
M Górski ◽  
...  
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Instability Strip ◽  
Pulsating Stars

Discovery of a Faint Short-Period Cataclysmic Variable in the Direction of the Large Magellanic Cloud: CAL 86 (RX J0546.3−6836)

2002 ◽  
Vol 123 (6) ◽  
pp. 3210-3215 ◽  
Author(s):  
P. C. Schmidtke ◽  
A. P. Cowley ◽  
J. B. Hutchings ◽  
David Crampton
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Cataclysmic Variable ◽  
Short Period

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

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.

scholarly journals Discovery of a Stellar Association Surrounding the Massive Binary Sk–67°105 in the Large Magellanic Cloud

1999 ◽  
Vol 190 ◽  
pp. 235-236
Author(s):  
P. G. Ostrov ◽  
V. S. Niemela ◽  
N. I. Morrell
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Stellar Association ◽  
Ob Stars ◽  
Spectroscopic Binary ◽  
Short Period ◽  
H Ii Region ◽  
Compact Cluster

Sk–67°105, a luminous O4f type stars in the Large Magellanic Cloud, is the exiting star of the H II region N 50 (DEM 193). Niemela & Morrell (1986) found this hot star to be a massive short period double lined spectroscopic binary. Because luminous OB stars are usually found in young stellar groups, we have searched for such an aggregate in the vicinity of Sk–67°105.Here we report, as a result of our search, the discovery of a new OB association in the LMC. We also find that Sk–67°105 is the most luminous star of a small compact cluster inside this OB association.

scholarly journals Candidates for non-pulsating stars located in the Cepheid instability strip in the Large Magellanic Cloud based on Strömgren photometry

2019 ◽  
Vol 489 (3) ◽  
pp. 3285-3293 ◽  
Author(s):  
Weronika Narloch ◽  
G Pietrzyński ◽  
Z Kołaczkowski ◽  
R Smolec ◽  
M Górski ◽  
...  
Keyword(s):  
Gravitational Lensing ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Instability Strip ◽  
Classical Cepheid ◽  
Pulsating Stars ◽  
Giant Stars ◽  
Classical Cepheids ◽  
Astrophysical Research

ABSTRACT We present candidates for non-pulsating stars lying in the classical Cepheid instability strip based on the Optical Gravitational Lensing Experiment (OGLE) photometric maps combined with Strömgren photometry obtained with the 4.1-m Southern Astrophysical Research (SOAR) telescope, and Gaia Data Release 2 data in four fields in the Large Magellanic Cloud. We selected 19 candidates in total. After analysis of their light curves from OGLE surveys we found that all these stars appear to be photometrically stable at the level of a few mmag. Our results show that non-pulsating stars might constitute to about $21\!-\!30\, {\rm per\, cent}$ of the whole sample of giant stars located in the classical instability strip. Furthermore, we identified potential candidates for classical Cepheids with hot companions based on their Strömgren colours.

scholarly journals Discovery of an ∼30-yr-duration post-nova pulsating supersoft source in the Large Magellanic Cloud

2020 ◽  
Vol 499 (2) ◽  
pp. 2007-2014
Author(s):  
G Vasilopoulos ◽  
F Koliopanos ◽  
T E Woods ◽  
F Haberl ◽  
M D Soraisam ◽  
...  
Keyword(s):  
White Dwarf ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
X Ray ◽  
Short Period ◽  
Type Ia ◽  
Nuclear Burning ◽  
Soft Spectrum ◽  
Binary Evolution ◽  
First Time

ABSTRACT Supersoft X-ray sources (SSS) have been identified as white dwarfs accreting from binary companions and undergoing nuclear burning of the accreted material on their surface. Although expected to be a relatively numerous population from both binary evolution models and their identification as type Ia supernova progenitor candidates, given the very soft spectrum of SSSs relatively few are known. Here we report on the X-ray and optical properties of 1RXS J050526.3−684628, a previously unidentified accreting nuclear-burning white dwarf located in the Large Magellanic Cloud (LMC). XMM–Newton observations enabled us to study its X-ray spectrum and measure for the first time short-period oscillations of ∼170 s. By analysing newly obtained X-ray data by eROSITA, together with Swift observations and archival ROSAT data, we have followed its long-term evolution over the last 3 decades. We identify 1RXS J050526.3−684628 as a slowly evolving post-nova SSS undergoing residual surface nuclear burning, which finally reached its peak in 2013 and is now declining. Though long expected on theoretical grounds, such long-lived residual-burning objects had not yet been found. By comparison with existing models, we find that the effective temperature and luminosity evolution are consistent with an ∼0.7 M⊙ carbon–oxygen white dwarf accreting ${\sim} 10^{-9}~\rm {M}_{\odot }$ yr−1. Our results suggest that there may be many more undiscovered SSSs and ‘missed’ novae awaiting dedicated deep X-ray searches in the LMC and elsewhere.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

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