2,927 research outputs found
The HATNet and HATSouth Exoplanet Surveys
The Hungarian-made Automated Telescope Network (HATNet) has been in operation
since 2003, with the key science goal being the discovery and accurate
characterization of transiting extrasolar planets (TEPs) around bright stars.
Using six small, 11\,cm\ aperture, fully automated telescopes in Arizona and
Hawaii, as of 2017 March, it has discovered and accurately characterized 67
such objects. The HATSouth network of telescopes has been in operation since
2009, using slightly larger, 18\,cm diameter optical tubes. It was the first
global network of telescopes using identical instrumentation. With three
premier sites spread out in longitude (Chile, Namibia, Australia), the HATSouth
network permits round-the-clock observations of a 128 square arcdegree swath of
the sky at any given time, weather permitting. As of this writing, HATSouth has
discovered 36 transiting exoplanets. Many of the altogether ~100 HAT and
HATSouth exoplanets were the first of their kind. They have been important
contributors to the rapidly developing field of exoplanets, motivating and
influencing observational techniques, theoretical studies, and also actively
shaping future instrumentation for the detection and characterization of such
objects.Comment: Invited review chapter, accepted for publication in "Handbook of
Exoplanets", edited by H.J. Deeg and J.A. Belmonte, Springer Reference Work
The rich frequency spectrum of the triple-mode variable AC And
Fourier analysis of the light curve of AC And from the HATNet database
reveals the rich frequency structure of this object. Above 30 components are
found down to the amplitude of 3 mmag. Several of these frequencies are not the
linear combinations of the three basic components. We detect period increase in
all three components that may lend support to the Pop I classification of this
variable.Comment: Poster presented at IAU Symposium 301, "Precision Asteroseismology -
Celebration of the Scientific Opus of Wojtek Dziembowski", 19-23 August 2013,
Wroclaw, Polan
HAT-P-12b: A Low-Density Sub-Saturn Mass Planet Transiting a Metal-Poor K Dwarf
We report on the discovery of HAT-P-12b, a transiting extrasolar planet
orbiting the moderately bright V=12.8 K4 dwarf GSC 03033-00706, with a period P
= 3.2130598 +- 0.0000021 d, transit epoch Tc = 2454419.19556 +- 0.00020 (BJD)
and transit duration 0.0974 +- 0.0006 d. The host star has a mass of 0.73 +-
0.02 Msun, radius of 0.70 +- ^0.02_0.01 Rsun, effective temperature 4650 +- 60
K and metallicity [Fe/H] = -0.29 +- 0.05. We find a slight correlation between
the observed spectral line bisector spans and the radial velocity, so we
consider, and rule out, various blend configurations including a blend with a
background eclipsing binary, and hierarchical triple systems where the
eclipsing body is a star or a planet. We conclude that a model consisting of a
single star with a transiting planet best fits the observations, and show that
a likely explanation for the apparent correlation is contamination from
scattered moonlight. Based on this model, the planetary companion has a mass of
0.211 +- 0.012 MJup, and a radius of 0.959 +- ^0.029_0.021 RJup yielding a mean
density of 0.295 +- 0.025 g cm^-3. Comparing these observations with recent
theoretical models we find that HAT-P-12b is consistent with a ~ 1-4.5 Gyr,
mildly irradiated, H/He dominated planet with a core mass Mc <~ 10 Mearth.
HAT-P-12b is thus the least massive H/He dominated gas giant planet found to
date. This record was previously held by Saturn.Comment: Accepted for publication in ApJ, 13 pages, 9 figures, 5 table
KOI-142, the King of Transit Variations, is a Pair of Planets near the 2:1 Resonance
The Transit Timing Variations (TTVs) can be used as a diagnostic of
gravitational interactions between planets in a multi-planet system. Many
Kepler Objects of Interest (KOIs) exhibit significant TTVs, but KOI-142.01
stands out among them with an unrivaled, 12-hour TTV amplitude. Here we report
a thorough analysis of KOI-142.01's transits. We discover periodic Transit
Duration Variations (TDVs) of KOI-142.01 that are nearly in phase with the
observed TTVs. We show that KOI-142.01's TTVs and TDVs uniquely detect a
non-transiting companion with a mass 0.7 that of Jupiter (KOI-142c).
KOI-142.01's mass inferred from the transit variations is consistent with the
measured transit depth, suggesting a Neptune class planet (KOI-142b). The
orbital period ratio P_c/P_b=2.03 indicates that the two planets are just wide
of the 2:1 resonance. The present dynamics of this system, characterized here
in detail, can be used to test various formation theories that have been
proposed to explain the near-resonant pairs of exoplanets
Radial velocities from the N2K Project: 6 new cold gas giant planets orbiting HD 55696, HD 98736, HD 148164, HD 203473, and HD 211810
The N2K planet search program was designed to exploit the planet-metallicity
correlation by searching for gas giant planets orbiting metal-rich stars. Here,
we present the radial velocity measurements for 378 N2K target stars that were
observed with the HIRES spectrograph at Keck Observatory between 2004 and 2017.
With this data set, we announce the discovery of six new gas giant exoplanets:
a double-planet system orbiting HD 148164 ( of 1.23 and 5.16 M) and single planet detections around HD 55696 ( = 3.87 M), HD 98736 ( = 2.33 M), HD 203473 ( = 7.8
M), and HD 211810 ( = 0.67 M). These gas
giant companions have orbital semi-major axes between 1.0 and 6.2 AU and
eccentricities ranging from 0.13 to 0.71. We also report evidence for three
gravitationally bound companions with between 20 to 30 M, placing them in the mass range of brown dwarfs, around HD 148284, HD
214823, and HD 217850, and four low mass stellar companions orbiting HD 3404,
HD 24505, HD 98630, and HD 103459. In addition, we present updated orbital
parameters for 42 previously announced planets. We also report a nondetection
of the putative companion HD 73256 b. Finally, we highlight the most promising
candidates for direct imaging and astrometric detection, and find that many hot
Jupiters from our sample could be detectable by state-of-the-art telescopes
such as Gaia.Comment: Accepted by the Astronomical Journal. 75 pages, 49 figure
- âŠ