Searching for variable stars in the cores of five metal-rich globular clusters using EMCCD observations

MiNDSTEp Consortium, D. M. Bramich

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Aims. In this paper, we present the analysis of time-series observations from 2013 and 2014 of five metal-rich ([Fe/H] > -1) globular clusters: NGC 6388, NGC 6441, NGC 6528, NGC 6638, and NGC 6652. The data have been used to perform a census of the variable stars in the central parts of these clusters. Methods. The observations were made with the electron-multiplying charge-couple device (EMCCD) camera at the Danish 1.54m Telescope at La Silla, Chile, and they were analysed using difference image analysis to obtain high-precision light curves of the variable stars. Results. It was possible to identify and classify all of the previously known or suspected variable stars in the central regions of the five clusters. Furthermore, we were able to identify and, in most cases, classify 48, 49, 7, 8, and 2 previously unknown variables in NGC 6388, NGC 6441, NGC 6528, NGC 6638, and NGC 6652, respectively. Especially interesting is the case of NGC 6441, for which the variable star population of about 150 stars has been thoroughly examined by previous studies, including a Hubble Space Telescope study. In this paper we are able to present 49 new variable stars for this cluster, of which one (possibly two) are RR Lyrae stars, two are W Virginis stars, and the rest are long-period semi-regular or irregular variables on the red giant branch. We have also detected the first double-mode RR Lyrae in the cluster.

Original languageEnglish
JournalAstronomy and Astrophysics
Volume573
DOIs
Publication statusPublished - 1 Jan 2015

Fingerprint

variable stars
globular clusters
image analysis
census
time series
electron
metal
metals
electrons
stars
Chile
Hubble Space Telescope
light curve
cameras
method
analysis
telescopes

Keywords

  • Globular clusters: individual
  • Instrumentation: high angular resolution
  • Stars: variables: general
  • Stars: variables: RR lyrae

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Searching for variable stars in the cores of five metal-rich globular clusters using EMCCD observations. / MiNDSTEp Consortium ; Bramich, D. M.

In: Astronomy and Astrophysics, Vol. 573, 01.01.2015.

Research output: Contribution to journalArticle

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title = "Searching for variable stars in the cores of five metal-rich globular clusters using EMCCD observations",
abstract = "Aims. In this paper, we present the analysis of time-series observations from 2013 and 2014 of five metal-rich ([Fe/H] > -1) globular clusters: NGC 6388, NGC 6441, NGC 6528, NGC 6638, and NGC 6652. The data have been used to perform a census of the variable stars in the central parts of these clusters. Methods. The observations were made with the electron-multiplying charge-couple device (EMCCD) camera at the Danish 1.54m Telescope at La Silla, Chile, and they were analysed using difference image analysis to obtain high-precision light curves of the variable stars. Results. It was possible to identify and classify all of the previously known or suspected variable stars in the central regions of the five clusters. Furthermore, we were able to identify and, in most cases, classify 48, 49, 7, 8, and 2 previously unknown variables in NGC 6388, NGC 6441, NGC 6528, NGC 6638, and NGC 6652, respectively. Especially interesting is the case of NGC 6441, for which the variable star population of about 150 stars has been thoroughly examined by previous studies, including a Hubble Space Telescope study. In this paper we are able to present 49 new variable stars for this cluster, of which one (possibly two) are RR Lyrae stars, two are W Virginis stars, and the rest are long-period semi-regular or irregular variables on the red giant branch. We have also detected the first double-mode RR Lyrae in the cluster.",
keywords = "Globular clusters: individual, Instrumentation: high angular resolution, Stars: variables: general, Stars: variables: RR lyrae",
author = "{MiNDSTEp Consortium} and Bramich, {D. M.} and Bramich, {D. M.} and {Figuera Jaimes}, R. and J{\o}rgensen, {U. G.} and N. Kains and {Arellano Ferro}, A. and Khalid Al-Subai and V. Bozza and {Calchi Novati}, S. and S. Ciceri and G. D'Ago and M. Dominik and P. Galianni and Gu, {S. H.} and Harps{\o}e, {K. B W} and T. Haugb{\o}lle and Hinse, {T. C.} and M. Hundertmark and D. Juncher and H. Korhonen and C. Liebig and L. Mancini and A. Popovas and M. Rabus and S. Rahvar and G. Scarpetta and Schmidt, {R. W.} and C. Snodgrass and J. Southworth and D. Starkey and Street, {R. A.} and J. Surdej and Wang, {X. B.} and O. Wertz",
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T1 - Searching for variable stars in the cores of five metal-rich globular clusters using EMCCD observations

AU - MiNDSTEp Consortium

AU - Bramich, D. M.

AU - Bramich, D. M.

AU - Figuera Jaimes, R.

AU - Jørgensen, U. G.

AU - Kains, N.

AU - Arellano Ferro, A.

AU - Al-Subai, Khalid

AU - Bozza, V.

AU - Calchi Novati, S.

AU - Ciceri, S.

AU - D'Ago, G.

AU - Dominik, M.

AU - Galianni, P.

AU - Gu, S. H.

AU - Harpsøe, K. B W

AU - Haugbølle, T.

AU - Hinse, T. C.

AU - Hundertmark, M.

AU - Juncher, D.

AU - Korhonen, H.

AU - Liebig, C.

AU - Mancini, L.

AU - Popovas, A.

AU - Rabus, M.

AU - Rahvar, S.

AU - Scarpetta, G.

AU - Schmidt, R. W.

AU - Snodgrass, C.

AU - Southworth, J.

AU - Starkey, D.

AU - Street, R. A.

AU - Surdej, J.

AU - Wang, X. B.

AU - Wertz, O.

PY - 2015/1/1

Y1 - 2015/1/1

N2 - Aims. In this paper, we present the analysis of time-series observations from 2013 and 2014 of five metal-rich ([Fe/H] > -1) globular clusters: NGC 6388, NGC 6441, NGC 6528, NGC 6638, and NGC 6652. The data have been used to perform a census of the variable stars in the central parts of these clusters. Methods. The observations were made with the electron-multiplying charge-couple device (EMCCD) camera at the Danish 1.54m Telescope at La Silla, Chile, and they were analysed using difference image analysis to obtain high-precision light curves of the variable stars. Results. It was possible to identify and classify all of the previously known or suspected variable stars in the central regions of the five clusters. Furthermore, we were able to identify and, in most cases, classify 48, 49, 7, 8, and 2 previously unknown variables in NGC 6388, NGC 6441, NGC 6528, NGC 6638, and NGC 6652, respectively. Especially interesting is the case of NGC 6441, for which the variable star population of about 150 stars has been thoroughly examined by previous studies, including a Hubble Space Telescope study. In this paper we are able to present 49 new variable stars for this cluster, of which one (possibly two) are RR Lyrae stars, two are W Virginis stars, and the rest are long-period semi-regular or irregular variables on the red giant branch. We have also detected the first double-mode RR Lyrae in the cluster.

AB - Aims. In this paper, we present the analysis of time-series observations from 2013 and 2014 of five metal-rich ([Fe/H] > -1) globular clusters: NGC 6388, NGC 6441, NGC 6528, NGC 6638, and NGC 6652. The data have been used to perform a census of the variable stars in the central parts of these clusters. Methods. The observations were made with the electron-multiplying charge-couple device (EMCCD) camera at the Danish 1.54m Telescope at La Silla, Chile, and they were analysed using difference image analysis to obtain high-precision light curves of the variable stars. Results. It was possible to identify and classify all of the previously known or suspected variable stars in the central regions of the five clusters. Furthermore, we were able to identify and, in most cases, classify 48, 49, 7, 8, and 2 previously unknown variables in NGC 6388, NGC 6441, NGC 6528, NGC 6638, and NGC 6652, respectively. Especially interesting is the case of NGC 6441, for which the variable star population of about 150 stars has been thoroughly examined by previous studies, including a Hubble Space Telescope study. In this paper we are able to present 49 new variable stars for this cluster, of which one (possibly two) are RR Lyrae stars, two are W Virginis stars, and the rest are long-period semi-regular or irregular variables on the red giant branch. We have also detected the first double-mode RR Lyrae in the cluster.

KW - Globular clusters: individual

KW - Instrumentation: high angular resolution

KW - Stars: variables: general

KW - Stars: variables: RR lyrae

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U2 - 10.1051/0004-6361/201424967

DO - 10.1051/0004-6361/201424967

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JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

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