113 research outputs found
Maximum Angular Separation Epochs for Exoplanet Imaging Observations
Direct imaging of exoplanets presents both significant challenges and
significant gains. The advantages primarily lie in receiving emitted and, with
future instruments, reflected photons at phase angles not accessible by other
techniques, enabling the potential for atmospheric studies and the detection of
rotation and surface features. The challenges are numerous and include
coronagraph development and achieving the necessary contrast ratio. Here, we
address the specific challenge of determining epochs of maximum angular
separation for the star and planet. We compute orbital ephemerides for known
transiting and radial velocity planets, taking Keplerian orbital elements into
account. We provide analytical expressions for angular star--planet separation
as a function of the true anomaly, including the locations of minimum and
maximum. These expressions are used to calculate uncertainties for maximum
angular separation as a function of time for the known exoplanets, and we
provide strategies for improving ephemerides with application to proposed and
planned imaging missions.Comment: 7 pages, 3 figures, 1 table, accepted for publication in the
Astronomical Journa
Insuring the Healthy or Insuring the Sick? The Dilemma of Regulating the Individual Health Insurance Market -- Short Case Studies of Six States
Looks at a range of regulatory strategies used to make individual health insurance policies more accessible and affordable. Assesses the effectiveness of regulatory reforms in Iowa, Kansas, Kentucky, Massachusetts, New Jersey, and Washington
Maximum Angular Separation Epochs for Exoplanet Imaging Observations
Direct imaging of exoplanets presents both significant challenges and significant gains. The advantages primarily lie in receiving emitted and, with future instruments, reflected photons at phase angles not accessible by other techniques, enabling the potential for atmospheric studies and the detection of rotation and surface features. The challenges are numerous and include coronagraph development and achieving the necessary contrast ratio. Here, we address the specific challenge of determining epochs of maximum angular separation for the star and planet. We compute orbital ephemerides for known transiting and radial velocity planets, taking Keplerian orbital elements into account. We provide analytical expressions for angular star–planet separation as a function of the true anomaly, including the locations of minimum and maximum. These expressions are used to calculate uncertainties for maximum angular separation as a function of time for the known exoplanets, and we provide strategies for improving ephemerides with application to proposed and planned imaging missions
On the Orbital Inclination of Proxima Centauri b
The field of exoplanetary science has seen discovery rates increase dramatically over recent years, due largely to the data from the Kepler mission. Even so, individual discoveries of planets orbiting nearby stars are very important for studies of characterization and near-term follow-up prospects. The recent discovery of a terrestrial planet candidate orbiting Proxima Centauri presents numerous opportunities for studying a super-Earth within our own stellar backyard. One of the remaining ambiguities of the discovery is the true mass of the planet since the discovery signature was obtained via radial velocities. Here, we describe the effect of orbital inclination on the Proxima Centauri planet, in terms of mass, radius, atmosphere, and albedo. We calculate the astrometric, angular separation, and reflected light properties of the planet including the effects of orbital eccentricity. We further provide dynamical simulations that show how the presence of additional terrestrial planets within the Habitable Zone varies as a function of inclination. Finally, we discuss these effects in the context of future space-based photometry and imaging missions that could potentially detect the planetary signature and resolve the inclination and mass ambiguity of the planet
Finding the Needles in the Haystacks: High-Fidelity Models of the Modern and Archean Solar System for Simulating Exoplanet Observations
We present two state-of-the-art models of the solar system, one corresponding
to the present day and one to the Archean Eon 3.5 billion years ago. Each model
contains spatial and spectral information for the star, the planets, and the
interplanetary dust, extending to 50 AU from the sun and covering the
wavelength range 0.3 to 2.5 micron. In addition, we created a spectral image
cube representative of the astronomical backgrounds that will be seen behind
deep observations of extrasolar planetary systems, including galaxies and Milky
Way stars. These models are intended as inputs to high-fidelity simulations of
direct observations of exoplanetary systems using telescopes equipped with
high-contrast capability. They will help improve the realism of observation and
instrument parameters that are required inputs to statistical observatory yield
calculations, as well as guide development of post-processing algorithms for
telescopes capable of directly imaging Earth-like planets.Comment: Accepted for publication in PAS
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