Open AccessA study of optically featureless objects from the EC Survey: searching for new southern BL Lac objects
Author(s) -
Sefako R. R.,
Glass I. S.,
Kilkenny D.,
De Jager O. C.,
Stobie R. S.,
O’Donoghue D.,
Koen C.
Publication year - 1999
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1999.02927.x
Subject(s) - physics , white dwarf , subdwarf , astrophysics , bl lac object , polarimetry , astronomy , blazar , cataclysmic variable star , massive compact halo object , stars , optics , gamma ray , scattering
In an attempt to discover new southern BL Lac objects, 14 optically featureless objects from the Edinburgh–Cape Survey were selected. Optical polarimetry and spectroscopy, radio and IR observations were carried out in order to improve their classifications. The 14 objects were examined according to special criteria that are described. Their UBV and JHK colour–colour distributions, spectrograms, radio observations and visible‐region polarimetry were utilized to conclude that the selected objects are not BL Lacs. Most of them are apparently not extragalactic objects. It is suggested that four of the 14 candidates are DC white dwarfs, one is a QSO, three are DA white dwarfs or sdB subdwarfs, one is a cataclysmic variable, one is a DAO/sdO and another is possibly a DA+dM binary (composite system with a ‘primary’ hot white dwarf and a ‘secondary’ M‐type main‐sequence dwarf) or a cataclysmic variable. One object is likely to be a subdwarf, while two remain unclassifiable.