The VVV Templates Project Towards an automated classification of VVV light-curves

I. Building a database of stellar variability in the near-infrared

¹ Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago Chile
e-mail: rangelon@astro.puc.cl
² Centro de Astro-Ingeniería, Pontificia Universidad Católica de Chile, Santiago, Chile
³ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
⁴ Millennium Institute of Astrophysics, Santiago, Chile
⁵ Computer Science Department, Pontificia Universidad Católica de Chile, Santiago, Chile
⁶ Leiden Observatory, Leiden, The Netherlands
⁷ Instituto de Astrofísica de Canarias (IAC), Vía Láctea s/n, 38200 La Laguna, Tenerife, Canary Islands, Spain
⁸ European Southern Observatory, Av. Alonso de Córdoba 3107, 19001 Casilla, Santiago, Chile
⁹ Instituto de Física y Astronomía, Universidad de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, 5030 Casilla, Chile
¹⁰ Centre for Astrophysics Research, University of Hertfordshire, Hatfield, AL10 9AB, UK
¹¹ Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy
¹² INAF – Osservatorio Astronomico di Padova, vicolo dell’Osservatorio 5, 35122 Padova, Italy
¹³ Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Hai Dian District, 100871 Beijing, PR China
¹⁴ Department of Astronomy, Peking University, Yi He Yuan Lu 5, Hai Dian District, 100871 Beijing, PR China
¹⁵ Facultad de Matematicas, Pontificia Universidad Católica de Chile, Santiago, Chile
¹⁶ Universidade Federal do Rio Grande do Norte, Campus Universitário Lagoa Nova, CEP 59078-970, Natal, Brasil
¹⁷ Korea National University of Education, San 7, GangNaeMyeon, CheongWonGun, 363-791 ChungBuk, The Republic of Korea
¹⁸ Subaru Telescope, National Astronomical Observatory of Japan, 650 North Aohoku Place, Hilo, HI 96720, USA
¹⁹ Nicolaus Copernicus Astronomical Center, Department of Astrophysics, ul. Rabiańska 8, 87-100 Toruń, Poland
²⁰ Departamento de Ciencias Físicas, Universidad Andrés Bello, Av. República 252, Santiago, Chile
²¹ Department of Astrophysics, University of La Laguna, Vía Láctea s/n, 38200 La Laguna, Tenerife, Canary Islands, Spain
²² Astronomical Institute, Graduate School of Science, Tohoku University, 6-3 Aramaki Aoba, Aoba-ku, Sendai, 980-8578 Miyagi, Japan
²³ Korea Astronomy and Space Science Institute, Daedeokdae-ro, Yuseong-gu, 305-348 Daejeon, Republic of Korea
²⁴ NationalAstronomical Observatory, Osawa 2-21-1, Mitaka, Tokyo, Japan
²⁵ Centro de Astrobiología (CSIC-INTA), Ctra. Ajalvir km 4, 28850 Torrejón de Ardoz, Madrid, Spain
²⁶ INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna, via Gobetti 101, 40129 Bologna, Italy
²⁷ Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan
²⁸ Research School of Astronomy & Astrophysics, Australian National University, Mt. Stromlo Observatory, ACT 2611, Australia
²⁹ Department of Astrophysics, Nagoya University, Furo-cho, Chikusa-ku, 464-8602 Nagoya, Japan
³⁰ Departamento de Ciencias de la Computación, Universidad de Chile, Casilla 2777, Av. Blanco Encalada 2120, Santiago, Chile
³¹ Laboratoire Lagrange (UMR 7293), Université Nice Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, BP 4229, 06304 Nice, France
³² Departamento de Física – ICEx – UFMG, Av. Antônio Carlos, 6627, 30270-901, Belo Horizonte, MG, Brazil
³³ Universidade Federal de Sergipe, Departamento de Física, Av. Marechal Rondon s/n, 49100-000 São Cristóvão, SE, Brazil
³⁴ South African Astronomical Observatory, PO Box 9, 7935 Observatory, South Africa
³⁵ Astrophysics, Cosmology and Gravity Centre, Astronomy Department, University of Cape Town, 7701 Rondebosch, South Africa

Received: 29 March 2014
Accepted: 13 May 2014

Abstract

Context. The Vista Variables in the Vía Láctea (VVV) ESO Public Survey is a variability survey of the Milky Way bulge and an adjacent section of the disk carried out from 2010 on ESO Visible and Infrared Survey Telescope for Astronomy (VISTA). The VVV survey will eventually deliver a deep near-IR atlas with photometry and positions in five passbands (ZYJHK_S) and a catalogue of 1−10 million variable point sources – mostly unknown – that require classifications.

Aims. The main goal of the VVV Templates Project, which we introduce in this work, is to develop and test the machine-learning algorithms for the automated classification of the VVV light-curves. As VVV is the first massive, multi-epoch survey of stellar variability in the near-IR, the template light-curves that are required for training the classification algorithms are not available. In the first paper of the series we describe the construction of this comprehensive database of infrared stellar variability.

Methods. First, we performed a systematic search in the literature and public data archives; second, we coordinated a worldwide observational campaign; and third, we exploited the VVV variability database itself on (optically) well-known stars to gather high-quality infrared light-curves of several hundreds of variable stars.

Results. We have now collected a significant (and still increasing) number of infrared template light-curves. This database will be used as a training-set for the machine-learning algorithms that will automatically classify the light-curves produced by VVV. The results of such an automated classification will be covered in forthcoming papers of the series.