16 research outputs found
Radial Velocity Studies of Close Binary Stars. IX
Radial-velocity measurements and sine-curve fits to the orbital velocity
variations are presented for the eighth set of ten close binary systems: AB
And, V402 Aur, V445 Cep, V2082 Cyg, BX Dra, V918 Her, V502 Oph, V1363 Ori, KP
Peg, V335 Peg. Half of the systems (V445 Cep, V2082 Cyg, V918 Her, V1363 Ori,
V335 Peg) were discovered photometrically by the Hipparcos mission and all
systems are double-lined (SB2) contact binaries. The broadening function method
permitted improvement of the orbital elements for AB And and V502 Oph. The
other systems have been observed for radial velocity variations for the first
time; in this group are five bright (V<7.5) binaries: V445 Cep, V2082 Cyg, V918
Her, KP Peg and V335 Peg. Several of the studied systems are prime candidates
for combined light and radial-velocity synthesis solutions.Comment: 17+ pages, 2 tables, 4 figure
First Results from the CHARA Array. I. An Interferometric and Spectroscopic Study of the Fast Rotator alpha Leonis (Regulus)
We report on K-band interferometric observations of the bright, rapidly
rotating star Regulus (type B7 V) made with the CHARA Array on Mount Wilson,
California. Through a combination of interferometric and spectroscopic
measurements, we have determined for Regulus the equatorial and polar diameters
and temperatures, the rotational velocity and period, the inclination and
position angle of the spin axis, and the gravity darkening coefficient. These
first results from the CHARA Array provide the first interferometric
measurement of gravity darkening in a rapidly rotating star and represent the
first detection of gravity darkening in a star that is not a member of an
eclipsing binary system.Comment: Accepted for publication in The Astrophysical Journal, 44 pages w/ 14
figure
Interferometric Observations of Rapidly Rotating Stars
Optical interferometry provides us with a unique opportunity to improve our
understanding of stellar structure and evolution. Through direct observation of
rotationally distorted photospheres at sub-milliarcsecond scales, we are now
able to characterize latitude dependencies of stellar radius, temperature
structure, and even energy transport. These detailed new views of stars are
leading to revised thinking in a broad array of associated topics, such as
spectroscopy, stellar evolution, and exoplanet detection. As newly advanced
techniques and instrumentation mature, this topic in astronomy is poised to
greatly expand in depth and influence.Comment: Accepted for publication in A&AR