7 research outputs found
Radial velocity variations of the pulsating subdwarf B star PG 1605+072
We present an analysis of high-speed spectroscopy of the pulsating subdwarf B
star PG 1605+072. Periodic radial motions are detected at frequencies similar
to those reported for photometric variations in the star, with amplitudes of up
to 6 km/s. Differences between relative strengths for given frequency peaks for
our velocity data and previously measured photometry are probably a result of
shifting of power between modes over time. Small differences in the detected
frequencies may also indicate mode-shifting. We report the detection of
line-shape variations using the moments of the cross correlation function
profiles. It may be possible to use the moments to identify the star's
pulsation modes.Comment: 5 pages, 6 figure
TOI-1338 : TESS' first transiting circumbinary planet
Funding: Funding for the DPAC has been provided by national institutions, in particular, the institutions participating in the Gaia Multilateral Agreement. W.F.W. and J.A.O.thank John Hood Jr. for his generous support of exoplanet research at SDSU. Support was also provided and acknowledged through NASA Habitable Worlds grant 80NSSC17K0741 and NASA XRP grant 80NSSC18K0519. This work is partly supported by NASA Habitable Worlds grant 80NSSC17K0741. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under grant No.(DGE-1746045). A.H.M.J.T. has received funding from the European Research Council (ERC) under the European Unionâs Horizon 2020 research and innovation programme (grant agreement No. 803193/BEBOP) and from a Leverhulme Trust Research Project grant No. RPG-2018-418. A.C. acknowledges support by CFisUC strategic project (UID/FIS/04564/2019).We report the detection of the first circumbinary planet (CBP) found by Transiting Exoplanet Survey Satellite (TESS). The target, a known eclipsing binary, was observed in sectors 1 through 12 at 30 minute cadence and in sectors 4 through 12 at 2 minute cadence. It consists of two stars with masses of 1.1 Mâ and 0.3 Mâ on a slightly eccentric (0.16), 14.6 day orbit, producing prominent primary eclipses and shallow secondary eclipses. The planet has a radius of âŒ6.9 Râ and was observed to make three transits across the primary star of roughly equal depths (âŒ0.2%) but different durationsâa common signature of transiting CBPs. Its orbit is nearly circular (e â 0.09) with an orbital period of 95.2 days. The orbital planes of the binary and the planet are aligned to within âŒ1°. To obtain a complete solution for the system, we combined the TESS photometry with existing ground-based radial-velocity observations in a numerical photometric-dynamical model. The system demonstrates the discovery potential of TESS for CBPs and provides further understanding of the formation and evolution of planets orbiting close binary stars.Publisher PDFPeer reviewe
An all-sky catalogue of solar-type dwarfs for exoplanetary transit surveys
Most future surveys designed to discover transiting exoplanets, including
TESS and PLATO, will target bright (V<13) and nearby solar-type stars having a
spectral type later than F5. In order to enhance the probability of identifying
transits, these surveys must cover a very large area on the sky, because of the
intrinsically low areal density of bright targets. Unfortunately, no existing
catalog of stellar parameters is both deep and wide enough to provide a
homogeneous input list. As the first Gaia data release exploitable for this
purpose is expected to be released not earlier than late 2017, we have devised
an improved reduced-proper-motion method to discriminate late field dwarfs and
giants by combining UCAC4 proper motions with APASS DR6 photometry, and relying
on RAVE DR4 as an external calibrator. The output, named UCAC4-RPM, is a
publicly-available, complete all-sky catalog of solar-type dwarfs down to
V3.0 subgiants. The relatively low amount of
contamination (defined as the fraction of false positives; <30%) also makes
UCAC4-RPM a useful tool for the past and ongoing ground-based transit surveys,
which need to discard candidate signals originating from early-type or giant
stars. As an application, we show how UCAC4-RPM may support the preparation of
the TESS (that will map almost the entire sky) input catalog and the input
catalog of PLATO, planned to survey more than half of the whole sky with
exquisite photometric precision.Comment: 14 page, 6 figures, 2 tables. Accepted in MNRA