5 research outputs found
Kepler-21b: A 1.6REarth Planet Transiting the Bright Oscillating F Subgiant Star HD 179070
We present Kepler observations of the bright (V=8.3), oscillating star HD
179070. The observations show transit-like events which reveal that the star is
orbited every 2.8 days by a small, 1.6 R_Earth object. Seismic studies of HD
179070 using short cadence Kepler observations show that HD 179070 has a
frequencypower spectrum consistent with solar-like oscillations that are
acoustic p-modes. Asteroseismic analysis provides robust values for the mass
and radius of HD 179070, 1.34{\pm}0.06 M{\circ} and 1.86{\pm}0.04 R{\circ}
respectively, as well as yielding an age of 2.84{\pm}0.34 Gyr for this F5
subgiant. Together with ground-based follow-up observations, analysis of the
Kepler light curves and image data, and blend scenario models, we
conservatively show at the >99.7% confidence level (3{\sigma}) that the transit
event is caused by a 1.64{\pm}0.04 R_Earth exoplanet in a 2.785755{\pm}0.000032
day orbit. The exoplanet is only 0.04 AU away from the star and our
spectroscopic observations provide an upper limit to its mass of ~10 M_Earth
(2-{\sigma}). HD 179070 is the brightest exoplanet host star yet discovered by
Kepler.Comment: Accepted to Ap
The GALAH survey: a catalogue of carbon-enhanced stars and CEMP candidates
Swan bands - characteristic molecular absorption features of the C
molecule - are a spectroscopic signature of carbon-enhanced stars. They can
also be used to identify carbon-enhanced metal-poor (CEMP) stars. The GALAH
(GALactic Archaeology with Hermes) is a magnitude-limited survey of stars
producing high-resolution, high signal-to-noise spectra. We used 627,708 GALAH
spectra to search for carbon-enhanced stars with a supervised and unsupervised
classification algorithm, relying on the imprint of the Swan bands. We
identified 918 carbon-enhanced stars, including 12 already described in the
literature. An unbiased selection function of the GALAH survey allows us to
perform a population study of carbon-enhanced stars. Most of them are giants,
out of which we find 28 CEMP candidates. A large fraction of our
carbon-enhanced stars with repeated observations show variation in radial
velocity, hinting that there is a large fraction of variables among them. 32 of
the detected stars also show strong Lithium enhancement in their spectra.Comment: 13+5 pages, 13 figures, 1 catalog, accepted to MNRA
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Avtomatika i telemechanika
(Abridged) The Maunakea Spectroscopic Explorer (MSE) is an end-to-end science platform for the design, execution and scientific exploitation of spectroscopic surveys. It will unveil the composition and dynamics of the faint Universe and impact nearly every field of astrophysics across all spatial scales, from individual stars to the largest scale structures in the Universe. Major pillars in the science program for MSE include (i) the ultimate Gaia follow-up facility for understanding the chemistry and dynamics of the distant Milky Way, including the outer disk and faint stellar halo at high spectral resolution (ii) galaxy formation and evolution at cosmic noon, via the type of revolutionary surveys that have occurred in the nearby Universe, but now conducted at the peak of the star formation history of the Universe (iii) derivation of the mass of the neutrino and insights into inflationary physics through a cosmological redshift survey that probes a large volume of the Universe with a high galaxy density. MSE is positioned to become a critical hub in the emerging international network of front-line astronomical facilities, with scientific capabilities that naturally complement and extend the scientific power of Gaia, the Large Synoptic Survey Telescope, the Square Kilometer Array, Euclid, WFIRST, the 30m telescopes and many more