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Title: Toward the detection of exoplanet transits with polarimetry

In contrast to photometric transits, whose peak signal occurs at mid-transit due to occultation of the brightest region of the disk, polarimetric transits provide a signal upon ingress and egress due to occultation of the polarized stellar limb. Limb polarization, the bright corollary to limb darkening, arises from the 90° scattering angle and low optical depth experienced by photons at the limb. In addition to the ratio R {sub p}/R {sub *}, the amplitude of a polarimetric transit is expected to be controlled by the strength and width of the stellar limb polarization profile, which depend on the scattering-to-total opacity ratio at the stellar limb. We present a short list of the systems providing the highest expected signal-to-noise ratio for detection of this effect, and we draw particular attention to HD 80606b. This planet is spin/orbit misaligned, has a three-hour ingress, and has a bright parent star, which make it an attractive target. We report on test observations of an HD 80606b ingress with the POLISH2 polarimeter at the Lick Observatory Shane 3 m telescope. We conclude that unmodeled telescope systematic effects prevented polarimetric detection of this event. We outline a roadmap for further refinements of exoplanet polarimetry, whose eventualmore » success will require a further factor of ten reduction in systematic noise.« less
Authors:
 [1] ;  [2]
  1. NASA Sagan Fellow. (United States)
  2. Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
Publication Date:
OSTI Identifier:
22370350
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 795; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLITUDES; DETECTION; NOISE; OPACITY; ORBITS; PHOTONS; PLANETS; POLARIMETERS; POLARIMETRY; POLARIZATION; REDUCTION; SATELLITES; SCATTERING; SIGNAL-TO-NOISE RATIO; SPIN; STARS; STELLAR ATMOSPHERES; TELESCOPES