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Prospects of detecting the polarimetric signature of the Earth-mass planet α Centauri B b with SPHERE/ZIMPOL

Milli, J. and Mouillet, D. and Mawet, D. and Schmid, H. M. and Bazzon, A. and Girard, J. H. and Dohlen, K. and Roelfsema, R. (2013) Prospects of detecting the polarimetric signature of the Earth-mass planet α Centauri B b with SPHERE/ZIMPOL. Astronomy and Astrophysics, 556 . Art. No. A64. ISSN 0004-6361. doi:10.1051/0004-6361/201321881. https://resolver.caltech.edu/CaltechAUTHORS:20150520-144759505

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Abstract

Context. Over the past five years, radial-velocity and transit techniques have revealed a new population of Earth-like planets with masses of a few Earth masses. Their very close orbit around their host star requires an exquisite inner working angle to be detected in direct imaging and sets a challenge for direct imagers that work in the visible range, such as SPHERE/ZIMPOL. Aims. Among all known exoplanets with less than 25 Earth masses we first predict the best candidate for direct imaging. Our primary objective is then to provide the best instrument setup and observing strategy for detecting such a peculiar object with ZIMPOL. As a second step, we aim at predicting its detectivity. Methods. Using exoplanet properties constrained by radial velocity measurements, polarimetric models and the diffraction propagation code CAOS, we estimate the detection sensitivity of ZIMPOL for such a planet in different observing modes of the instrument. We show how observing strategies can be optimized to yield the best detection performance on a specific target. Results. In our current knowledge of exoplanetary systems, α Centauri B b is the most promising target with less than 25 Earth masses for ZIMPOL. With a gaseous Rayleigh-scattering atmosphere and favorable inclinations, the planet could be detected in about four hours of observing time, using the four-quadrant phase-mask coronograph in the I band. However, if α Centauri B b should display unfavorable polarimetric and reflective properties similar to that of our Moon, it is around 50 times fainter than the best sensitivity of ZIMPOL. Conclusions. α Centauri B is a primary target for SPHERE. Dedicated deep observations specifically targeting the radial velocity-detected planet can lead to a detection if the polarimetric properties of the planet are favorable.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1051/0004-6361/201321881DOIArticle
http://www.aanda.org/articles/aa/abs/2013/08/aa21881-13/aa21881-13.htmlPublisherArticle
http://arxiv.org/abs/1306.1006arXivDiscussion Paper
ORCID:
AuthorORCID
Milli, J.0000-0001-9325-2511
Mawet, D.0000-0002-8895-4735
Girard, J. H.0000-0001-8627-0404
Alternate Title:Prospects of detecting the polarimetric signature of the Earth-mass planet alpha Centauri B b with SPHERE/ZIMPOL
Additional Information:© 2013 ESO. Received 12 May 2013; Accepted 4 June 2013.
Subject Keywords:instrumentation: high angular resolution; planets and satellites: detection; instrumentation: polarimeters; polarization; planets and satellites: individual: alpha Centauri; planets and satellites: atmospheres
DOI:10.1051/0004-6361/201321881
Record Number:CaltechAUTHORS:20150520-144759505
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150520-144759505
Official Citation:Milli, J., Mouillet, D., Mawet, D., Schmid, H. M., Bazzon, A., Girard, J. H., . . . Roelfsema, R. (2013). Prospects of detecting the polarimetric signature of the Earth-mass planet α Centauri B b with SPHERE/ZIMPOL. A&A, 556, A64.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:57722
Collection:CaltechAUTHORS
Deposited By:INVALID USER
Deposited On:20 May 2015 23:16
Last Modified:10 Nov 2021 21:54

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