Ground-based astrometric detection of exoplanets with CAPSCam
| Main Authors: | Astraatmadja, Tri L., Weinberger, Alycia J., Boss, Alan P. |
|---|---|
| Format: | info Proceeding |
| Bahasa: | eng |
| Terbitan: |
, 2019
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| Subjects: | |
| Online Access: |
https://zenodo.org/record/3524632 |
| ctrlnum |
3524632 |
|---|---|
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<dc schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd"><creator>Astraatmadja, Tri L.</creator><creator>Weinberger, Alycia J.</creator><creator>Boss, Alan P.</creator><date>2019-10-21</date><description>Since 2007 we have been engaged in an astrometric search for exoplanets using the Carnegie Astrometric Planet Search Camera (CAPSCam) mounted on the 2.5-meter du Pont Telescope at the Las Campanas Observatory, Chile. This program targets about 100 nearby (mainly within about 15 pc) late M, L, and T dwarfs. These nearby low-mass stars are selected to maximize the potential to discover planetary companions by ground-based astrometry, which is more suitable to detect long-period exoplanets than Doppler spectroscopy or transits. Detecting long-period exoplanets allows us to determine long-period exoplanet demographics, a key constraint on theoretical models of gas giant planet formation. With an observing cadence of roughly 3--5 nights every 2 months and in addition to the long-time baseline observations, CAPSCam has the potential to make the first astrometric discovery of an exoplanet orbiting a single star. The challenge of ground-based astrometric data reduction, however, is to properly correct for atmospheric distortion, in addition to the optical distortion of the telescope and instrument. We found that this is possible by building an optical distortion model using orthonormal Zernike polynomials. The suitable polynomial order and coefficients of this model can be determined by cross-validation, using the stars in the Gaia DR2 catalogue as reference. The resulting calibrated epoch measurements can then be fit with a 5-parameter astrometric model (positions, proper motions, and parallax) or a 12-parameter model that includes an orbital solution (5 astrometric parameters, 6 orbital elements, and a mass ratio). By comparing the probabilities of these two models, we can assess the strength of the evidence for the presence of planetary companions for our target stars. We show some preliminary results of these analyses for some promising candidates.</description><description>There are animations in this presentation. Use Adobe Acrobat Reader to view the animations. It's the only way I know on how to play the animations inside a PDF file.</description><identifier>https://zenodo.org/record/3524632</identifier><identifier>10.5281/zenodo.3524632</identifier><identifier>oai:zenodo.org:3524632</identifier><language>eng</language><relation>doi:10.5281/zenodo.3524631</relation><relation>url:https://zenodo.org/communities/bdexocon-oct2014</relation><rights>info:eu-repo/semantics/openAccess</rights><rights>https://creativecommons.org/licenses/by/4.0/legalcode</rights><subject>astronomy</subject><subject>astrometry</subject><subject>exoplanet</subject><subject>brown dwarfs</subject><subject>CAPS</subject><subject>CAPSCam</subject><title>Ground-based astrometric detection of exoplanets with CAPSCam</title><type>Other:info:eu-repo/semantics/lecture</type><type>Journal:Proceeding</type><recordID>3524632</recordID></dc>
|
| language |
eng |
| format |
Other:info:eu-repo/semantics/lecture Other Journal:Proceeding Journal |
| author |
Astraatmadja, Tri L. Weinberger, Alycia J. Boss, Alan P. |
| title |
Ground-based astrometric detection of exoplanets with CAPSCam |
| publishDate |
2019 |
| topic |
astronomy astrometry exoplanet brown dwarfs CAPS CAPSCam |
| url |
https://zenodo.org/record/3524632 |
| contents |
Since 2007 we have been engaged in an astrometric search for exoplanets using the Carnegie Astrometric Planet Search Camera (CAPSCam) mounted on the 2.5-meter du Pont Telescope at the Las Campanas Observatory, Chile. This program targets about 100 nearby (mainly within about 15 pc) late M, L, and T dwarfs. These nearby low-mass stars are selected to maximize the potential to discover planetary companions by ground-based astrometry, which is more suitable to detect long-period exoplanets than Doppler spectroscopy or transits. Detecting long-period exoplanets allows us to determine long-period exoplanet demographics, a key constraint on theoretical models of gas giant planet formation. With an observing cadence of roughly 3--5 nights every 2 months and in addition to the long-time baseline observations, CAPSCam has the potential to make the first astrometric discovery of an exoplanet orbiting a single star. The challenge of ground-based astrometric data reduction, however, is to properly correct for atmospheric distortion, in addition to the optical distortion of the telescope and instrument. We found that this is possible by building an optical distortion model using orthonormal Zernike polynomials. The suitable polynomial order and coefficients of this model can be determined by cross-validation, using the stars in the Gaia DR2 catalogue as reference. The resulting calibrated epoch measurements can then be fit with a 5-parameter astrometric model (positions, proper motions, and parallax) or a 12-parameter model that includes an orbital solution (5 astrometric parameters, 6 orbital elements, and a mass ratio). By comparing the probabilities of these two models, we can assess the strength of the evidence for the presence of planetary companions for our target stars. We show some preliminary results of these analyses for some promising candidates. There are animations in this presentation. Use Adobe Acrobat Reader to view the animations. It's the only way I know on how to play the animations inside a PDF file. |
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