270 research outputs found
KELT-1b: A Strongly Irradiated, Highly Inflated, Short Period, 27 Jupiter-mass Companion Transiting a mid-F Star
We present the discovery of KELT-1b, the first transiting low-mass companion
from the wide-field Kilodegree Extremely Little Telescope-North (KELT-North)
survey. The V=10.7 primary is a mildly evolved, solar-metallicity, mid-F star.
The companion is a low-mass brown dwarf or super-massive planet with mass of
27.23+/-0.50 MJ and radius of 1.110+0.037-0.024 RJ, on a very short period
(P=1.21750007) circular orbit. KELT-1b receives a large amount of stellar
insolation, with an equilibrium temperature assuming zero albedo and perfect
redistribution of 2422 K. Upper limits on the secondary eclipse depth indicate
that either the companion must have a non-zero albedo, or it must experience
some energy redistribution. Comparison with standard evolutionary models for
brown dwarfs suggests that the radius of KELT-1b is significantly inflated.
Adaptive optics imaging reveals a candidate stellar companion to KELT-1, which
is consistent with an M dwarf if bound. The projected spin-orbit alignment
angle is consistent with zero stellar obliquity, and the vsini of the primary
is consistent with tidal synchronization. Given the extreme parameters of the
KELT-1 system, we expect it to provide an important testbed for theories of the
emplacement and evolution of short-period companions, and theories of tidal
dissipation and irradiated brown dwarf atmospheres.Comment: 30 pages, 19 figures. Submitted to Ap
KELT-2Ab: A Hot Jupiter Transiting the Bright (V=8.77) Primary Star of a Binary System
We report the discovery of KELT-2Ab, a hot Jupiter transiting the bright
(V=8.77) primary star of the HD 42176 binary system. The host is a slightly
evolved late F-star likely in the very short-lived "blue-hook" stage of
evolution, with \teff=6148\pm48{\rm K}, and
\feh=0.034\pm0.78. The inferred stellar mass is
\msun\ and the star has a relatively large radius
of \rsun. The planet is a typical hot Jupiter with
period days and a mass of \mj\ and
radius of \rj. This is mildly inflated as compared
to models of irradiated giant planets at the 4 Gyr age of the system.
KELT-2A is the third brightest star with a transiting planet identified by
ground-based transit surveys, and the ninth brightest star overall with a
transiting planet. KELT-2Ab's mass and radius are unique among the subset of
planets with host stars, and therefore increases the diversity of bright
benchmark systems. We also measure the relative motion of KELT-2A and -2B over
a baseline of 38 years, robustly demonstrating for the first time that the
stars are bound. This allows us to infer that KELT-2B is an early K-dwarf. We
hypothesize that through the eccentric Kozai mechanism KELT-2B may have
emplaced KELT-2Ab in its current orbit. This scenario is potentially testable
with Rossiter-McLaughlin measurements, which should have an amplitude of
44 m s.Comment: 9 pages, 2 tables, 4 figures. A short video describing this paper is
available at http://www.youtube.com/watch?v=wVS8lnkXXlE. Revised to reflect
the ApJL version. Note that figure 4 is not in the ApJL versio
KELT-7b: A hot Jupiter transiting a bright V=8.54 rapidly rotating F-star
We report the discovery of KELT-7b, a transiting hot Jupiter with a mass of
MJ, radius of RJ, and an orbital
period of days. The bright host star (HD33643;
KELT-7) is an F-star with , Teff K, [Fe/H]
, and . It has a mass of
Msun, a radius of Rsun, and
is the fifth most massive, fifth hottest, and the ninth brightest star known to
host a transiting planet. It is also the brightest star around which KELT has
discovered a transiting planet. Thus, KELT-7b is an ideal target for detailed
characterization given its relatively low surface gravity, high equilibrium
temperature, and bright host star. The rapid rotation of the star (
km/s) results in a Rossiter-McLaughlin effect with an unusually large amplitude
of several hundred m/s. We find that the orbit normal of the planet is likely
to be well-aligned with the stellar spin axis, with a projected spin-orbit
alignment of degrees. This is currently the second most
rapidly rotating star to have a reflex signal (and thus mass determination) due
to a planetary companion measured.Comment: Accepted to The Astronomical Journa
Optimizing Retention in a Pragmatic Trial of CommunityâLiving Older Persons: The STRIDE Study
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155912/1/jgs16356.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155912/2/jgs16356_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155912/3/jgs16356-sup-0001-supinfo.pd
KELT-6b: A P~7.9 d Hot Saturn Transiting a Metal-Poor Star with a Long-Period Companion
We report the discovery of KELT-6b, a mildly-inflated Saturn-mass planet
transiting a metal-poor host. The initial transit signal was identified in
KELT-North survey data, and the planetary nature of the occulter was
established using a combination of follow-up photometry, high-resolution
imaging, high-resolution spectroscopy, and precise radial velocity
measurements. The fiducial model from a global analysis including constraints
from isochrones indicates that the V=10.38 host star (BD+31 2447) is a mildly
evolved, late-F star with T_eff=6102 \pm 43 K, log(g_*)=4.07_{-0.07}^{+0.04}
and [Fe/H]=-0.28 \pm 0.04, with an inferred mass M_*=1.09 \pm 0.04 M_sun and
radius R_star=1.58_{-0.09}^{+0.16} R_sun. The planetary companion has mass
M_P=0.43 \pm 0.05 M_J, radius R_P=1.19_{-0.08}^{+0.13} R_J, surface gravity
log(g_P)=2.86_{-0.08}^{+0.06}, and density rho_P=0.31_{-0.08}^{+0.07}
g~cm^{-3}. The planet is on an orbit with semimajor axis a=0.079 \pm 0.001 AU
and eccentricity e=0.22_{-0.10}^{+0.12}, which is roughly consistent with
circular, and has ephemeris of T_c(BJD_TDB)=2456347.79679 \pm 0.00036 and
P=7.845631 \pm 0.000046 d. Equally plausible fits that employ empirical
constraints on the host star parameters rather than isochrones yield a larger
planet mass and radius by ~4-7%. KELT-6b has surface gravity and incident flux
similar to HD209458b, but orbits a host that is more metal poor than HD209458
by ~0.3 dex. Thus, the KELT-6 system offers an opportunity to perform a
comparative measurement of two similar planets in similar environments around
stars of very different metallicities. The precise radial velocity data also
reveal an acceleration indicative of a longer-period third body in the system,
although the companion is not detected in Keck adaptive optics images.Comment: Published in AJ, 17 pages, 15 figures, 6 table
KELT-6b: A P ~ 7.9 Day Hot Saturn Transiting a Metal-poor Star with a Long-period Companion
We report the discovery of KELT-6b, a mildly inflated Saturn-mass planet transiting a metal-poor host. The initial transit signal was identified in KELT-North survey data, and the planetary nature of the occulter was established using a combination of follow-up photometry, high-resolution imaging, high-resolution spectroscopy, and precise radial velocity measurements. The fiducial model from a global analysis including constraints from isochrones indicates that the V = 10.38 host star (BD+31 2447) is a mildly evolved, late-F star with T eff = 6102 ± 43 K, , and [Fe/H] = â0.28 ± 0.04, with an inferred mass M = 1.09 ± 0.04 M â and radius . The planetary companion has mass MP = 0.43 ± 0.05 M Jup, radius , surface gravity , and density . The planet is on an orbit with semimajor axis a = 0.079 ± 0.001 AU and eccentricity , which is roughly consistent with circular, and has ephemeris of T c(BJDTDB) = 2456347.79679 ± 0.00036 and P = 7.845631 ± 0.000046 days. Equally plausible fits that employ empirical constraints on the host-star parameters rather than isochrones yield a larger planet mass and radius by ~4}-7}. KELT-6b has surface gravity and incident flux similar to HD 209458b, but orbits a host that is more metal poor than HD 209458 by ~0.3 dex. Thus, the KELT-6 system offers an opportunity to perform a comparative measurement of two similar planets in similar environments around stars of very different metallicities. The precise radial velocity data also reveal an acceleration indicative of a longer-period third body in the system, although the companion is not detected in Keck adaptive optics images
The First Habitable Zone Earth-Sized Planet From TESS II: Spitzer Confirms TOI-700 d
We present Spitzer 4.5 ÎŒm observations of the transit of TOI-700 d, a habitable-zone Earth-sized planet in a multiplanet system transiting a nearby M-dwarf star (TIC 150428135, 2MASS J06282325â6534456). TOI-700 d has a radius of 1.144^(+0.062)_(-0.061) Râ and orbits within its host star's conservative habitable zone with a period of 37.42 days (T_(eq) ~ 269 K). TOI-700 also hosts two small inner planets (R_b = 1.037^(+0.0065)_(-0.064) Râ and R_c = 2.65^(+0.16)_(-0.15) Râ) with periods of 9.98 and 16.05 days, respectively. Our Spitzer observations confirm the Transiting Exoplanet Survey Satellite (TESS) detection of TOI-700 d and remove any remaining doubt that it is a genuine planet. We analyze the Spitzer light curve combined with the 11 sectors of TESS observations and a transit of TOI-700 c from the LCOGT network to determine the full system parameters. Although studying the atmosphere of TOI-700 d is not likely feasible with upcoming facilities, it may be possible to measure the mass of TOI-700 d using state-of-the-art radial velocity (RV) instruments (expected RV semiamplitude of ~70 cm sâ»Âč)
TIC 168789840: A Sextuply-Eclipsing Sextuple Star System
We report the discovery of a sextuply-eclipsing sextuple star system from
TESS data, TIC 168789840, also known as TYC 7037-89-1, the first known sextuple
system consisting of three eclipsing binaries. The target was observed in
Sectors 4 and 5 during Cycle 1, with lightcurves extracted from TESS Full Frame
Image data. It was also previously observed by the WASP survey and ASAS-SN. The
system consists of three gravitationally-bound eclipsing binaries in a
hierarchical structure of an inner quadruple system with an outer binary
subsystem. Follow-up observations from several different observatories were
conducted as a means of determining additional parameters. The system was
resolved by speckle interferometry with a 0."42 separation between the inner
quadruple and outer binary, inferring an estimated outer period of ~2 kyr. It
was determined that the fainter of the two resolved components is an 8.217 day
eclipsing binary, which orbits the inner quadruple that contains two eclipsing
binaries with periods of 1.570 days and 1.306 days. MCMC analysis of the
stellar parameters has shown that the three binaries of TIC 168789840 are
"triplets", as each binary is quite similar to the others in terms of mass,
radius, and Teff. As a consequence of its rare composition, structure, and
orientation, this object can provide important new insight into the formation,
dynamics, and evolution of multiple star systems. Future observations could
reveal if the intermediate and outer orbital planes are all aligned with the
planes of the three inner eclipsing binaries
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