295 research outputs found
Trajectory Design for the Lunar Polar Hydrogen Mapper Mission
The presented trajectory was designed for the Lunar Polar Hydrogen Mapper (LunaH-Map) 6U CubeSat, which was awarded a ride on NASAs Space Launch System (SLS) with Exploration Mission 1 (EM-1) via NASAs 2015 SIMPLEX proposal call. After deployment from EM-1s upper stage (which is planned to enter heliocentric space via a lunar flyby), the LunaH-Map CubeSat will alter its trajectory via its low-thrust ion engine to target a lunar flyby that yields a Sun-Earth-Moon weak stability boundary transfer to set up a ballistic lunar capture. Finally, the orbit energy is lowered to reach the required quasi-frozen science orbit with periselene above the lunar south pole
Astrophysical False Positives Encountered in Wide-Field Transit Searches
Wide-field photometric transit surveys for Jupiter-sized planets are
inundated by astrophysical false positives, namely systems that contain an
eclipsing binary and mimic the desired photometric signature. We discuss
several examples of such false alarms. These systems were initially identified
as candidates by the PSST instrument at Lowell Observatory. For three of the
examples, we present follow-up spectroscopy that demonstrates that these
systems consist of (1) an M-dwarf in eclipse in front of a larger star, (2) two
main-sequence stars presenting grazing-incidence eclipses, and (3) the blend of
an eclipsing binary with the light of a third, brighter star. For an additional
candidate, we present multi-color follow-up photometry during a subsequent time
of eclipse, which reveals that this candidate consists of a blend of an
eclipsing binary and a physically unassociated star. We discuss a couple
indicators from publicly-available catalogs that can be used to identify which
candidates are likely giant stars, a large source of the contaminants in such
surveys.Comment: 10 pages, 9 figures, to appear in AIP Conf Proc: The Search for Other
Worlds, eds. S. S. Holt & D. Demin
The Challenge of Wide-Field Transit Surveys: The Case of GSC 01944-02289
Wide-field searches for transiting extra-solar giant planets face the
difficult challenge of separating true transit events from the numerous false
positives caused by isolated or blended eclipsing binary systems. We describe
here the investigation of GSC 01944-02289, a very promising candidate for a
transiting brown dwarf detected by the Transatlantic Exoplanet Survey (TrES)
network. The photometry and radial velocity observations suggested that the
candidate was an object of substellar mass in orbit around an F star. However,
careful analysis of the spectral line shapes revealed a pattern of variations
consistent with the presence of another star whose motion produced the
asymmetries observed in the spectral lines of the brightest star. Detailed
simulations of blend models composed of an eclipsing binary plus a third star
diluting the eclipses were compared with the observed light curve and used to
derive the properties of the three components. Our photometric and
spectroscopic observations are fully consistent with a blend model of a
hierarchical triple system composed of an eclipsing binary with G0V and M3V
components in orbit around a slightly evolved F5 dwarf. We believe that this
investigation will be helpful to other groups pursuing wide-field transit
searches as this type of false detection could be more common than true
transiting planets, and difficult to identify.Comment: To appear in ApJ, v. 621, 2005 March 1
The Kepler Follow-up Observation Program
The Kepler Mission was launched on March 6, 2009 to perform a photometric
survey of more than 100,000 dwarf stars to search for terrestrial-size planets
with the transit technique. Follow-up observations of planetary candidates
identified by detection of transit-like events are needed both for
identification of astrophysical phenomena that mimic planetary transits and for
characterization of the true planets and planetary systems found by Kepler. We
have developed techniques and protocols for detection of false planetary
transits and are currently conducting observations on 177 Kepler targets that
have been selected for follow-up. A preliminary estimate indicates that between
24% and 62% of planetary candidates selected for follow-up will turn out to be
true planets.Comment: 12 pages, submitted to the Astrophysical Journal Letter
Metal clad aramid fibers for aerospace wire and cable
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TrES-1: The Transiting Planet of a Bright K0V Star
We report the detection of a transiting Jupiter-sized planet orbiting a
relatively bright (V=11.79) K0V star. We detected the transit light-curve
signature in the course of the TrES multi-site transiting planet survey, and
confirmed the planetary nature of the companion via multicolor photometry and
precise radial velocity measurements. We designate the planet TrES-1; its
inferred mass is 0.75 +/- 0.07 Jupiter masses, its radius is 1.08 (+0.18/-0.04)
Jupiter radii, and its orbital period is 3.030065 +/- 0.000008 days. This
planet has an orbital period similar to that of HD 209458b, but about twice as
long as those of the OGLE transiting planets. Its mass is indistinguishable
from that of HD 209458b, but its radius is significantly smaller and fits the
theoretical models without the need for an additional source of heat deep in
the atmosphere, as has been invoked by some investigators for HD 209458b.Comment: 15 pages, 3 figures, 2 tables. To be published in Astrophysical
Journal Letters. Ascii data in
http://www.hao.ucar.edu/public/research/stare/data/TrES1.as
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Kepler-4B: A Hot Neptune-Like Planet of A G0 Star Near Main-Sequence Turnoff
Early time-series photometry from NASA's Kepler spacecraft has revealed a planet transiting the star we term Kepler-4, at R.A. = 19(h)02(m)27.(s)68, delta = +50 degrees 08'08 '' 7. The planet has an orbital period of 3.213 days and shows transits with a relative depth of 0.87 x 10(-3) and a duration of about 3.95 hr. Radial velocity (RV) measurements from the Keck High Resolution Echelle Spectrometer show a reflex Doppler signal of 9.3(-1.9)(+1.1) m s(-1), consistent with a low-eccentricity orbit with the phase expected from the transits. Various tests show no evidence for any companion star near enough to affect the light curve or the RVs for this system. From a transit-based estimate of the host star's mean density, combined with analysis of high-resolution spectra, we infer that the host star is near turnoff from the main sequence, with estimated mass and radius of 1.223(-0.091)(+0.053) M(circle dot) and 1.487(-0.084)(+0.071) R(circle dot).We estimate the planet mass and radius to be {M(P), R(P)} = {24.5 +/- 3.8 M(circle plus), 3.99 +/- 0.21 R(circle plus)}. The planet's density is near 1.9 g cm(-3); it is thus slightly denser and more massive than Neptune, but about the same size.W. M. Keck FoundationNASA's Science Mission DirectorateAstronom
Discovery of the Transiting Planet Kepler-5B
We present 44 days of high duty cycle, ultra precise photometry of the 13th magnitude star Kepler-5 (KIC 8191672, T(eff) = 6300 K, log g = 4.1), which exhibits periodic transits with a depth of 0.7%. Detailed modeling of the transit is consistent with a planetary companion with an orbital period of 3.548460 +/- 0.000032 days and a radius of 1.431(-0.052)(+0.041) R(J). Follow-up radial velocity measurements with the Keck HIRES spectrograph on nine separate nights demonstrate that the planet is more than twice as massive as Jupiter with a mass of 2.114(-0.059)(+0.056) M(J) and a mean density of 0.894 +/- 0.079 g cm(-3).NASA's Science Mission DirectorateAstronom
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