30 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
KELT-3b: A Hot Jupiter Transiting a V=9.8 Late-F Star
We report the discovery of KELT-3b, a moderately inflated transiting hot
Jupiter with a mass of 1.477 (-0.067, +0.066) M_J, and radius of 1.345 +/-
0.072 R_J, with an orbital period of 2.7033904 +/- 0.000010 days. The host
star, KELT-3, is a V=9.8 late F star with M_* = 1.278 (-0.061, +0.063) M_sun,
R_* = 1.472 (-0.067, +0.065) R_sun, T_eff = 6306 (-49, +50) K, log(g) = 4.209
(-0.031, +0.033), and [Fe/H] = 0.044 (-0.082, +0.080), and has a likely proper
motion companion. KELT-3b is the third transiting exoplanet discovered by the
KELT survey, and is orbiting one of the 20 brightest known transiting planet
host stars, making it a promising candidate for detailed characterization
studies. Although we infer that KELT-3 is significantly evolved, a preliminary
analysis of the stellar and orbital evolution of the system suggests that the
planet has likely always received a level of incident flux above the
empirically-identified threshold for radius inflation suggested by Demory &
Seager (2011).Comment: 12 pages, 12 figures, accepted to Ap
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] = –0.28 ± 0.04, with an inferred mass M = 1.09 ± 0.04 M ☉ 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
KELT-16b: A Highly Irradiated, Ultra-short Period Hot Jupiter Nearing Tidal Disruption
We announce the discovery of KELT-16b, a highly irradiated, ultra-short
period hot Jupiter transiting the relatively bright () star TYC
2688-1839-1. A global analysis of the system shows KELT-16 to be an F7V star
with K, ,
[Fe/H] = -0.002, , and . The planet is a
relatively high mass inflated gas giant with , , density g cm, surface
gravity , and K. The best-fitting linear ephemeris is BJD and d.
KELT-16b joins WASP-18b, -19b, -43b, -103b, and HATS-18b as the only giant
transiting planets with day. Its ultra-short period and high
irradiation make it a benchmark target for atmospheric studies by HST, Spitzer,
and eventually JWST. For example, as a hotter, higher mass analog of WASP-43b,
KELT-16b may feature an atmospheric temperature-pressure inversion and
day-to-night temperature swing extreme enough for TiO to rain out at the
terminator. KELT-16b could also join WASP-43b in extending tests of the
observed mass-metallicity relation of the Solar System gas giants to higher
masses. KELT-16b currently orbits at a mere 1.7 Roche radii from its
host star, and could be tidally disrupted in as little as a few
years (for a stellar tidal quality factor of ). Finally, the
likely existence of a widely separated bound stellar companion in the KELT-16
system makes it possible that Kozai-Lidov oscillations played a role in driving
KELT-16b inward to its current precarious orbit.Comment: 16 pages, 18 Figures, 7 Tables, Accepted for publication in A