2,610 research outputs found
'Rapid fire' spectroscopy of Kepler solar-like oscillators
The NASA Kepler mission has been continuously monitoring the same field of
the sky since the successful launch in March 2009, providing high-quality
stellar lightcurves that are excellent data for asteroseismology, far superior
to any other observations available at the present. In order to make a
meaningful analysis and interpretation of the asteroseismic data, accurate
fundamental parameters for the observed stars are needed. The currently
available parameters are quite uncertain as illustrated by e.g. Thygesen et al.
(A&A 543, A160, 2012), who found deviations as extreme as 2.0 dex in [Fe/H] and
log g, compared to catalogue values. Thus, additional follow-up observations
for these targets are needed in order to put firm limits on the parameter space
investigated by the asteroseismic modellers. Here, we propose a metod for
deriving accurate metallicities of main sequence and subgiant solar-like
oscillators from medium resolution spectra with a moderate S/N. The method
takes advantage of the additional constraints on the fundamental parameters,
available from asteroseismology and multi-color photometry. The approach
enables us to reduce the analysis overhead significantly when doing spectral
synthesis, which in turn will increases the efficiency of follow-up
observations.Comment: 3 pages, 2 figures. Proceedings from Asteroseismology of Stellar
Populations in the Milky Way 2013 to appear in 'Astrophysics and Space
Science Proceedings
How Well Do We Know the Beta-Decay of 16N and Oxygen Formation in Helium Burning
We review the status of the 12C(a,g)16O reaction rate, of importance for
stellar processes in a progenitor star prior to a super-nova collapse. Several
attempts to constrain the p-wave S-factor of the 12C(a,g)16O reaction at Helium
burning temperatures (200 MK) using the beta-delayed alpha-particle emission of
16N have been made, and it is claimed that this S-factor is known, as quoted by
the TRIUMF collaboration. In contrast reanalyses (by G.M. hale) of all thus far
available data (including the 16N data) does not rule out a small S-factor
solution. Furthermore, we improved our previous Yale-UConn study of the beta-
delayed alpha-particle emission of \n16 by improving our statistical sample (by
more than a factor of 5), improving the energy resolution of the experiment (by
20%), and in understanding our line shape, deduced from measured quantities.
Our newly measured spectrum of the beta-delayed alpha-particle emission of 16N
is not consistent with the TRIUMF('94) data, but is consistent with the
Seattle('95) data, as well as the earlier (unaltered !) data of Mainz('71). The
implication of this discrepancies for the extracted astrophysical p-wave
s-factor is briefly discussed.Comment: 6 pages, 4 figures, Invited Talk, Physics With Radioactive Beams,
Puri, India, Jan. 12-17, 1998, Work Supported by USDOE Grant No.
DE-FG02-94ER4087
Managed Bumblebees Outperform Honeybees in Increasing Peach Fruit Set in China: Different Limiting Processes with Different Pollinators
© 2015 Zhang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. http://creativecommons.org/licenses/by/4.0/ The file attached is the published version of the article
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