RR Lyrae mode switching in globular cluster M 68 (NGC 4590)

被引：4

作者：

Kains, N. ^{[1
]}

Bramich, D. M. ^{[2
]}

Ferro, A. Arellano ^{[3
]}

Jaimes, R. Figuera ^{[4
,5
]}

机构：

[1] Space Telescope Sci Inst, Baltimore, MD 21218 USA

[2] Qatar Fdn, Qatar Environm & Energy Res Inst, Doha, Qatar

[3] Univ Nacl Autonoma Mexico, Inst Astron, Mexico City 04510, DF, Mexico

[4] Univ St Andrews, SUPA Sch Phys & Astron, St Andrews KY16 9SS, Fife, Scotland

[5] European So Observ, D-85748 Garching, Germany

来源：

ASTRONOMY & ASTROPHYSICS | 2015年 / 582卷

关键词：

stars: variables: RR Lyrae; globular clusters: individual: M 68 (NGC 4590); LARGE-MAGELLANIC-CLOUD; DIFFERENCE IMAGE-ANALYSIS; VARIABLE-STAR POPULATION; HORIZONTAL-BRANCH; CCD PHOTOMETRY; M68; SEARCH; PULSATIONS; PARAMETERS; CATALOG;

D O I：

10.1051/0004-6361/201526819

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We build on our detailed analysis of time-series observations of the globular cluster M 68 to investigate the irregular pulsational behaviour of four of the RR Lyrae stars in this cluster. M 68 is one of only two globular clusters in which mode switching of RR Lyrae stars has previously been reported. We discuss one additional case, as well as a case of irregular behaviour, and we briefly revisit the two previously reported cases with a homogeneous analysis. We find that in 2013, V45 was pulsating in the first-overtone mode alone, despite being previously reported as a double-mode (fundamental and first overtone) pulsator in 1994, and that the amplitude of the fundamental mode in V7 is increasing with time. We also suggest that V21 might not have switched pulsation modes as previously reported, although the first overtone seems to be becoming less dominant. Finally, our analysis of available archival data confirms that V33 lost a pulsation mode between 1950 and 1986.

引用

页数：6

共 45 条

[1] The MACHO project: Microlensing results from 5.7 years of Large Magellanic Cloud observations [J].