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

Jesper Skottfelt; D. M. Bramich; R. Figuera Jaimes; U. G. Jørgensen; N. Kains; A. Arellano Ferro; K. A. Alsubai; V. Bozza; S. Calchi Novati; S. Ciceri; G. D'Ago; M. Dominik; P. Galianni; S. -H. Gu; K. B. W Harpsøe; Troels Haugbølle; T. C. Hinse; M. Hundertmark; D. Juncher; H. Korhonen; C. Liebig; L. Mancini; A. Popovas; M. Rabus; S. Rahvar; G. Scarpetta; R. W. Schmidt; C. Snodgrass; J. Southworth; D. Starkey; R. A. Street; J. Surdej; X. -B. Wang; O. Wertz

doi:10.1051/0004-6361/201424967

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

Jesper Skottfelt, D. M. Bramich, R. Figuera Jaimes, U. G. Jørgensen, N. Kains, A. Arellano Ferro, K. A. Alsubai, V. Bozza, S. Calchi Novati, S. Ciceri, G. D'Ago, M. Dominik, P. Galianni, S. -H. Gu, K. B. W Harpsøe, Troels Haugbølle, T. C. Hinse, M. Hundertmark, D. Juncher, H. KorhonenC. Liebig, L. Mancini, A. Popovas, M. Rabus, S. Rahvar, G. Scarpetta, R. W. Schmidt, C. Snodgrass, J. Southworth, D. Starkey, R. A. Street, J. Surdej, X. -B. Wang, O. Wertz

Astrophysics and Planetary Science

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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 language	English
Article number	A103
Journal	Astronomy & Astrophysics
Volume	573
Number of pages	23
ISSN	0004-6361
DOIs	https://doi.org/10.1051/0004-6361/201424967
Publication status	Published - 1 Jan 2015

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Skottfelt, J., Bramich, D. M., Jaimes, R. F., Jørgensen, U. G., Kains, N., Ferro, A. A., Alsubai, K. A., Bozza, V., Novati, S. C., Ciceri, S., D'Ago, G., Dominik, M., Galianni, P., Gu, S. .-H., Harpsøe, K. B. W., Haugbølle, T., Hinse, T. C., Hundertmark, M., Juncher, D., ... Wertz, O. (2015). Searching for variable stars in the cores of five metal-rich globular clusters using EMCCD observations. Astronomy & Astrophysics, 573, Article A103. https://doi.org/10.1051/0004-6361/201424967

Skottfelt, J, Bramich, DM, Jaimes, RF, Jørgensen, UG, Kains, N, Ferro, AA, Alsubai, KA, Bozza, V, Novati, SC, Ciceri, S, D'Ago, G, Dominik, M, Galianni, P, Gu, S-H, Harpsøe, KBW, Haugbølle, T, Hinse, TC, Hundertmark, M, Juncher, D, Korhonen, H, Liebig, C, Mancini, L, Popovas, A, Rabus, M, Rahvar, S, Scarpetta, G, Schmidt, RW, Snodgrass, C, Southworth, J, Starkey, D, Street, RA, Surdej, J, Wang, X-B & Wertz, O 2015, 'Searching for variable stars in the cores of five metal-rich globular clusters using EMCCD observations', Astronomy & Astrophysics, vol. 573, A103. https://doi.org/10.1051/0004-6361/201424967

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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 = "astro-ph.SR",

author = "Jesper Skottfelt and Bramich, {D. M.} and Jaimes, {R. Figuera} and J{\o}rgensen, {U. G.} and N. Kains and Ferro, {A. Arellano} and Alsubai, {K. A.} and V. Bozza and Novati, {S. Calchi} 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 Troels 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",

year = "2015",

month = jan,

day = "1",

doi = "10.1051/0004-6361/201424967",

language = "English",

volume = "573",

journal = "Astronomy & Astrophysics",

issn = "0004-6361",

publisher = "E D P Sciences",

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TY - JOUR

T1 - Searching for variable stars in the cores of five metal-rich globular clusters using EMCCD observations

AU - Skottfelt, Jesper

AU - Bramich, D. M.

AU - Jaimes, R. Figuera

AU - Jørgensen, U. G.

AU - Kains, N.

AU - Ferro, A. Arellano

AU - Alsubai, K. A.

AU - Bozza, V.

AU - Novati, S. Calchi

AU - Ciceri, S.

AU - D'Ago, G.

AU - Dominik, M.

AU - Galianni, P.

AU - Gu, S. -H.

AU - Harpsøe, K. B. W

AU - Haugbølle, Troels

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 - astro-ph.SR

U2 - 10.1051/0004-6361/201424967

DO - 10.1051/0004-6361/201424967

M3 - Journal article

SN - 0004-6361

VL - 573

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

M1 - A103

ER -

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

Abstract

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