1,726 research outputs found
World-leading science with SPIRou - the nIR spectropolarimeter / high-precision velocimeter for CFHT
SPIRou is a near-infrared (nIR) spectropolarimeter / velocimeter proposed as
a new-generation instrument for CFHT. SPIRou aims in particular at becoming
world-leader on two forefront science topics, (i) the quest for habitable
Earth-like planets around very- low-mass stars, and (ii) the study of low-mass
star and planet formation in the presence of magnetic fields. In addition to
these two main goals, SPIRou will be able to tackle many key programs, from
weather patterns on brown dwarf to solar-system planet atmospheres, to dynamo
processes in fully-convective bodies and planet habitability. The science
programs that SPIRou proposes to tackle are forefront (identified as first
priorities by most research agencies worldwide), ambitious (competitive and
complementary with science programs carried out on much larger facilities, such
as ALMA and JWST) and timely (ideally phased with complementary space missions
like TESS and CHEOPS).
SPIRou is designed to carry out its science mission with maximum efficiency
and optimum precision. More specifically, SPIRou will be able to cover a very
wide single-shot nIR spectral domain (0.98-2.35 \mu m) at a resolving power of
73.5K, providing unpolarized and polarized spectra of low-mass stars with a
~15% average throughput and a radial velocity (RV) precision of 1 m/s.Comment: 12 pages, 5 figures, conference proceedings of the French Society of
Astronomy and Astrophysics meeting 201
The Science Case for an Extended Spitzer Mission
Although the final observations of the Spitzer Warm Mission are currently
scheduled for March 2019, it can continue operations through the end of the
decade with no loss of photometric precision. As we will show, there is a
strong science case for extending the current Warm Mission to December 2020.
Spitzer has already made major impacts in the fields of exoplanets (including
microlensing events), characterizing near Earth objects, enhancing our
knowledge of nearby stars and brown dwarfs, understanding the properties and
structure of our Milky Way galaxy, and deep wide-field extragalactic surveys to
study galaxy birth and evolution. By extending Spitzer through 2020, it can
continue to make ground-breaking discoveries in those fields, and provide
crucial support to the NASA flagship missions JWST and WFIRST, as well as the
upcoming TESS mission, and it will complement ground-based observations by LSST
and the new large telescopes of the next decade. This scientific program
addresses NASA's Science Mission Directive's objectives in astrophysics, which
include discovering how the universe works, exploring how it began and evolved,
and searching for life on planets around other stars.Comment: 75 pages. See page 3 for Table of Contents and page 4 for Executive
Summar
Radial Velocity Prospects Current and Future: A White Paper Report prepared by the Study Analysis Group 8 for the Exoplanet Program Analysis Group (ExoPAG)
[Abridged] The Study Analysis Group 8 of the NASA Exoplanet Analysis Group
was convened to assess the current capabilities and the future potential of the
precise radial velocity (PRV) method to advance the NASA goal to "search for
planetary bodies and Earth-like planets in orbit around other stars.: (U.S.
National Space Policy, June 28, 2010). PRVs complement other exoplanet
detection methods, for example offering a direct path to obtaining the bulk
density and thus the structure and composition of transiting exoplanets. Our
analysis builds upon previous community input, including the ExoPlanet
Community Report chapter on radial velocities in 2008, the 2010 Decadal Survey
of Astronomy, the Penn State Precise Radial Velocities Workshop response to the
Decadal Survey in 2010, and the NSF Portfolio Review in 2012. The
radial-velocity detection of exoplanets is strongly endorsed by both the Astro
2010 Decadal Survey "New Worlds, New Horizons" and the NSF Portfolio Review,
and the community has recommended robust investment in PRVs. The demands on
telescope time for the above mission support, especially for systems of small
planets, will exceed the number of nights available using instruments now in
operation by a factor of at least several for TESS alone. Pushing down towards
true Earth twins will require more photons (i.e. larger telescopes), more
stable spectrographs than are currently available, better calibration, and
better correction for stellar jitter. We outline four hypothetical situations
for PRV work necessary to meet NASA mission exoplanet science objectives.Comment: ExoPAG SAG 8 final report, 112 pages, fixed author name onl
On the behaviour of spin-orbit connection of exoplanets
Star-planet interactions play, among other things, a crucial role in
planetary orbital configurations by circularizing orbits, aligning the star and
planet spin and synchronizing stellar rotation with orbital motions. This is
especially true for innermost giant planets, which can be schematized as binary
systems with a very large mass ratio. Despite a few examples where spin-orbit
synchronization has been obtained, there is no demographic study on synchronous
regimes in those systems yet. Here we use a sample of 1,055 stars with
innermost planet companions to show the existence of three observational loci
of star-planet synchronization regimes. Two of them have dominant fractions of
subsynchronous and supersynchronous star-planet systems, and a third less
populated regime of potentially synchronized systems. No synchronous
star-planet system with a period higher than 40 days has been detected yet.
This landscape is different from eclipsing binary systems, most of which are
synchronized. We suggest that planets in a stable asynchronous spin state
belonging to star-planet systems in a supersynchronized regime offer the most
favourable conditions for habitability.Comment: 15 pages, 1 figure in main paper, 6 supplementary figures. Published
in Nature Astronomy, May 202
SpinSpotter: An Automated Algorithm for Identifying Stellar Rotation Periods With Autocorrelation Analysis
Spinspotter is a robust and automated algorithm designed to extract stellar
rotation periods from large photometric datasets with minimal supervision. Our
approach uses the autocorrelation function (ACF) to identify stellar rotation
periods up to one-third the observational baseline of the data. Our algorithm
also provides a suite of diagnostics that describe the features in the ACF,
which allows the user to fine-tune the tolerance with which to accept a period
detection. We apply it to approximately 130,000 main-sequence stars observed by
the Transiting Exoplanet Survey Satellite (TESS) at 2-minute cadence during
Sectors 1-26, and identify rotation periods for 13,504 stars ranging from 0.4
to 14 days. We demonstrate good agreement between our sample and known values
from the literature and note key differences between our population of rotators
and those previously identified in the Kepler field, most notably a large
population of fast-rotating M dwarfs. Our sample of rotating stars provides a
data set with coverage of nearly the entire sky that can be used as a basis for
future gyrochronological studies, and, when combined with proper motions and
distances from Gaia, to search for regions with high densities of young stars,
thus identifying areas of recent star formation and undiscovered moving group
members. Our algorithm is publicly available for download and use on GitHub.Comment: 14 pages, 5 figures, Accepted for publication in The Astrophysical
Journa
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