Bibcode
Ulla, A.; Thejll, P.
Bibliographical reference
Astronomy and Astrophysics Supplement, v.132, p.1-12
Advertised on:
10
1998
Citations
53
Refereed citations
39
Description
In our search, started in February, 1994, for JHK excess fluxes among
the hot subdwarf population as an indicator for the presence of binary
companions, results for 72 more hot objects (=63 hot subdwarfs + 1
Horizontal Branch B star + 7 white dwarfs + 1 non-subdwarf object)
observed with the Carlos Sanchez CVF IR photometer (in June and October,
1994), are presented. The exact number of binary hot subdwarfs has
gained renewed importance after the recent discovery of pulsators with
G-F companions. The total number of candidates we propose may help to
set some constraints; for example, out of 41 objects with excesses, 13
may have G-type binary companions. From our new sample, 14 discoveries
of binary candidates have been found: BD+25 4655, Feige 108, HD 4539, HD
149382, HD 216135, KPD 2109+440, LSI+63 198, LSIV+10 9, LSV+22 38, PG
0011+221, PG 0116+242, PG 0314+103, PG 2151+100 and TON 139. Besides, 2
more from reanalysis of February, 1994, data - BD+37 1977 and BD+48
1777, may now be found to be IR excess candidates. Two suspected
binaries, PB 8555 and SB 7, are also confirmed. By fitting cite[Kurucz
(1993)]{kur93} model spectra and assuming zero-age main sequence
companions, we find upper limits on the subdwarf gravities. The
distributions of upper limits on log(g), mostly between about 5.25 and
6.5, are nearly identical for both sdBs and sdOs. Figure~1 is only
available in the electronic version of the paper
(http://www.edpsciences.com)