134 research outputs found
Selenium and tellurium content of stony meteorites by neutron activation
By neutron activation analysis the Se- and Te-content of four chondritic meteorites have been determined. The average content is 9.8 +/- 2.5 and 0.61 +/- 1.7 p.p.m., respectively. These values are lower than those already reported in the literature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32424/1/0000503.pd
A new HW Vir binary from the Palomar Transient Factory: PTF1 J072455.75+125300.3 - An eclipsing subdwarf B binary with a M-star companion
We report the discovery of an eclipsing binary -- PTF1 J072456125301--
composed of a subdwarf B (sdB) star () with a faint companion.
Subdwarf B stars are core helium-burning stars, which can be found on the
extreme horizontal branch. About half of them reside in close binary systems,
but few are known to be eclipsing, for which fundamental stellar parameters can
be derived.\newline We conducted an analysis of photometric data and spectra
from the Palomar 60'' and the 200" Hale telescope respectively. A quantitative
spectral analysis found an effective temperature of
\,K, log g = and
log(, typical for an sdB star. The
companion does not contribute to the optical light of the system, except
through a distinct reflection effect. From the light curve an orbital period of
0.09980(25)\,d and a system inclination of 83.56\pm0.30\,^{\circ} were
derived. The radial velocity curve yielded an orbital semi-amplitude of
K_1=95.8\pm 8.1\,\text{km s^{-1}}. The mass for the M-type dwarf companion
is . PTF1\,J072456125301 has similar atmospheric
parameters to those of pulsating sdB stars (V346 Hya stars). Therefore it could
be a high-priority object for asteroseismology, if pulsations were detected
such as in the enigmatic case of NY Vir.Comment: Accepted to A&A, 7pages, 4 figure
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