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We report photometric and spectroscopic observations of the black hole binary GRO J1655-40 in complete quiescence. In contrast to the 1995 photometry, the light curves from 1996 are almost completely dominated by ellipsoidal modulations from the secondary star. Model fits to the light curves, which take into account the temperature profile of the accretion(More)
When an extrasolar planet passes in front of (transits) its star, its radius can be measured from the decrease in starlight and its orbital period from the time between transits. Multiple planets transiting the same star reveal much more: period ratios determine stability and dynamics, mutual gravitational interactions reflect planet masses and orbital(More)
A small group of X-ray binaries currently provides the best evidence for the existence of stellar-mass black holes. These objects are interacting binary systems where the X-rays arise from accretion of material onto a compact object (i.e. an object with a radius of less than a few hundred km). In some favourable cases, optical studies of the companion star(More)
Optical spectroscopic observations of the companion star (type G8IV to K4III) in the microquasar system XTE J1550-564 reveal a radial velocity curve with a best fitting spectroscopic period of P sp = 1.552 ± 0.010 days and a semiamplitude of K 2 = 349 ± 12 km s −1. The optical mass function is f (M) = 6.86 ± 0.71 M ⊙ (1σ). We tentatively measure the(More)
We report on the X-ray spectral behavior of XTE J1550–564 during its 1998-99 outburst. XTE J1550–564 is an exceptionally bright X-ray nova and is also the third Galactic black hole candidate known to exhibit quasiperiodic X-ray oscillations above 50 Hz. Our study is based on 209 pointed observations using the PCA and HEXTE instruments onboard the Rossi(More)
An extensive grid of synthetic mid-and far-ultraviolet spectra for accretion disks in cata-clysmic variables has been presented by Wade and Hubeny (1998). In those models, the disk was assumed to be in steady-state, that is T eff (r) is specified completely by the mass M WD and radius R WD of the accreting white dwarf star and the mass transfer rate ˙ M(More)
The Kepler spacecraft is monitoring more than 150,000 stars for evidence of planets transiting those stars. We report the detection of two Saturn-size planets that transit the same Sun-like star, based on 7 months of Kepler observations. Their 19.2- and 38.9-day periods are presently increasing and decreasing at respective average rates of 4 and 39 minutes(More)
We present the detection of five planets--Kepler-62b, c, d, e, and f--of size 1.31, 0.54, 1.95, 1.61 and 1.41 Earth radii (R⊕), orbiting a K2V star at periods of 5.7, 12.4, 18.2, 122.4, and 267.3 days, respectively. The outermost planets, Kepler-62e and -62f, are super-Earth-size (1.25 R⊕ < planet radius ≤ 2.0 R⊕) planets in the habitable zone of their host(More)
We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements, along with high-resolution imaging and spectroscopy,(More)
The Kepler spacecraft has been monitoring the light from 150,000 stars in its primary quest to detect transiting exoplanets. Here, we report on the detection of an eclipsing stellar hierarchical triple, identified in the Kepler photometry. KOI-126 [A, (B, C)], is composed of a low-mass binary [masses M(B) = 0.2413 ± 0.0030 solar mass (M(⊙)), M(C) = 0.2127 ±(More)