III. New discoveries and their IR spectral energy distributions
Instituto de Geofísica y Astronomía, Calle 212, N. 2906, CP
11600, La Habana, Cuba
2 Instituto de Astrofísica de Canarias, 38200, La Laguna, Tenerife, Spain
3 Departamento de Astrofísica, Universidad de La Laguna, 38206, La Laguna, Tenerife, Spain
4 Grantecan S.A., Centro de Astrofísica de La Palma, 38712 Breña Baja, La Palma, Spain
5 INAF, Osservatorio Astronomico di Padova, 36012 Asiago, Italy
6 IGAM, Institut für Physik, Universität Graz, 8010 Graz, Austria
7 Centro de Astrobiología, CSIC-INTA, 28850 Torrejón de Ardoz, Spain
8 Observatorio Astronómico Nacional (OAN-IGN), 28014 Madrid, Spain
Received: 3 December 2013
Accepted: 13 March 2014
Context. The IPHAS Hα survey provides a rich database to search for emission-line sources in the northern Galactic plane.
Aims. We are systematically searching for symbiotic stars in the Milky Way using IPHAS. Our final goal, a complete census of this class of objects in the Galaxy, is a fundamental figure for discussing their overall properties and relevance to other classes of stars.
Methods. Candidate symbiotic stars were selected using a refined combination of IPHAS and 2MASS photometric colours. Optical spectroscopy, together with the analysis of their spectral energy distribution in the IR, were obtained to confirm their nature and determine their main properties.
Results. Five new symbiotic stars have been confirmed from spectroscopy at the 10.4 m GTC telescope. In one case, confirming the presence of a red giant star required near infrared spectroscopy. In another case, its symbiotic nature was adopted based on the strong similarity of its optical spectrum and spectral energy distribution to those of other genuinely symbiotic stars. The spectral energy distribution of the two S-types found is well fitted by red-giant model atmospheres up to 22 μm without evidence of IR excesses due to dust. In contrast, the three D-types mostly show emission from hot dust with a temperature around 1000 K. We also present the spectroscopic and photometric monitoring of the symbiotic star IPHASJ190832.31+051226.6 that was originally discovered in outburst, and it has now returned to a lower luminosity status. The spectra of thirteen other sources, all classified as young stellar objects except for a new compact planetary nebula, are also presented.
Conclusions. The refinement of our discovery method, the completion of the IPHAS survey and photometric calibration, and the start of the twin survey in the south, VPHAS+, provide excellent perspectives for completing a reliable census of symbiotic stars in the Galaxy in the next few years.
Key words: binaries: symbiotic / surveys / stars: pre-main sequence / planetary nebulae: individual: IPHASJ191942.91+162128.0 / stars: AGB and post-AGB
Appendices are available in electronic form at http://www.aanda.org
Spectra are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (18.104.22.168) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/567/A49
© ESO, 2014