Millimagnitude photometry for transiting extrasolar planetary candidates. IV. Solution to the puzzle of the extremely red OGLE-TR-82 primary

We present precise new V-, I-, and Ks-band photometry for the planetary-transit candidate star OGLE-TR-82. V-band images acquired in good seeing with the VIMOS instrument at the Very Large Telescope allowed us to measure V= 20.61 ± 0.03 mag for this star despite the presence of a brighter neighbor a...

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Detalles Bibliográficos
Publicado: 2007
Materias:
Planets and satellites: formation
Stars: individual (OGLE-TR-82)
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v669_n2_p1345_Hoyer
http://hdl.handle.net/20.500.12110/paper_0004637X_v669_n2_p1345_Hoyer
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_0004637X_v669_n2_p1345_Hoyer
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spelling paper:paper_0004637X_v669_n2_p1345_Hoyer2023-06-08T14:28:54Z Millimagnitude photometry for transiting extrasolar planetary candidates. IV. Solution to the puzzle of the extremely red OGLE-TR-82 primary Planets and satellites: formation Stars: individual (OGLE-TR-82) We present precise new V-, I-, and Ks-band photometry for the planetary-transit candidate star OGLE-TR-82. V-band images acquired in good seeing with the VIMOS instrument at the Very Large Telescope allowed us to measure V= 20.61 ± 0.03 mag for this star despite the presence of a brighter neighbor about 1″ away. This faint magnitude answers the question why it has not been possible to measure radial velocities for this object. One transit of this star has been observed with the GMOS-S instrument on Gemini South in the i and g bands, which allowed us to verify that this is not a false positive, to confirm the transit amplitude measured by OGLE, and to improve the ephemeris. The transit is better defined in the i-band light curve (with a depth of Ai = 0.034 mag), than in the g band (Ag = 0.1 mag), in which the star is significantly fainter. Near-IR photometry obtained with the SOFI array at the ESO New Technology Telescope yields K= 12.20 ± 0.10 and V-K= 8.40 ± 0.10, so red that it is unlike any transit candidate studied before. With the new data, we consider two possible configurations for the system: (1) a nearby M7 V star or (2) a blend with a very reddened, distant red giant. The first hypothesis would give a radius for the companion of R p = 0.3 ± 0.1 RJ, i.e., the size of Neptune. Quantitative analysis of near-IR spectroscopy finally shows that OGLE-TR-82 is a distant, reddened, metal-poor early K giant, confirmed by direct comparison with stellar templates, which gives as a best match a K3 III star. Therefore, we rule out a planetary nature for the companion, and conclude that this system is a main-sequence binary blended with a background red giant. As a case study, a system that can so mimic a planetary transit presents a lesson for future transit surveys. © 2007. The American Astronomical Society. All rights reserved. 2007 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v669_n2_p1345_Hoyer http://hdl.handle.net/20.500.12110/paper_0004637X_v669_n2_p1345_Hoyer
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Planets and satellites: formation
Stars: individual (OGLE-TR-82)
spellingShingle Planets and satellites: formation
Stars: individual (OGLE-TR-82)
Millimagnitude photometry for transiting extrasolar planetary candidates. IV. Solution to the puzzle of the extremely red OGLE-TR-82 primary
topic_facet Planets and satellites: formation
Stars: individual (OGLE-TR-82)
description We present precise new V-, I-, and Ks-band photometry for the planetary-transit candidate star OGLE-TR-82. V-band images acquired in good seeing with the VIMOS instrument at the Very Large Telescope allowed us to measure V= 20.61 ± 0.03 mag for this star despite the presence of a brighter neighbor about 1″ away. This faint magnitude answers the question why it has not been possible to measure radial velocities for this object. One transit of this star has been observed with the GMOS-S instrument on Gemini South in the i and g bands, which allowed us to verify that this is not a false positive, to confirm the transit amplitude measured by OGLE, and to improve the ephemeris. The transit is better defined in the i-band light curve (with a depth of Ai = 0.034 mag), than in the g band (Ag = 0.1 mag), in which the star is significantly fainter. Near-IR photometry obtained with the SOFI array at the ESO New Technology Telescope yields K= 12.20 ± 0.10 and V-K= 8.40 ± 0.10, so red that it is unlike any transit candidate studied before. With the new data, we consider two possible configurations for the system: (1) a nearby M7 V star or (2) a blend with a very reddened, distant red giant. The first hypothesis would give a radius for the companion of R p = 0.3 ± 0.1 RJ, i.e., the size of Neptune. Quantitative analysis of near-IR spectroscopy finally shows that OGLE-TR-82 is a distant, reddened, metal-poor early K giant, confirmed by direct comparison with stellar templates, which gives as a best match a K3 III star. Therefore, we rule out a planetary nature for the companion, and conclude that this system is a main-sequence binary blended with a background red giant. As a case study, a system that can so mimic a planetary transit presents a lesson for future transit surveys. © 2007. The American Astronomical Society. All rights reserved.
title Millimagnitude photometry for transiting extrasolar planetary candidates. IV. Solution to the puzzle of the extremely red OGLE-TR-82 primary
title_short Millimagnitude photometry for transiting extrasolar planetary candidates. IV. Solution to the puzzle of the extremely red OGLE-TR-82 primary
title_full Millimagnitude photometry for transiting extrasolar planetary candidates. IV. Solution to the puzzle of the extremely red OGLE-TR-82 primary
title_fullStr Millimagnitude photometry for transiting extrasolar planetary candidates. IV. Solution to the puzzle of the extremely red OGLE-TR-82 primary
title_full_unstemmed Millimagnitude photometry for transiting extrasolar planetary candidates. IV. Solution to the puzzle of the extremely red OGLE-TR-82 primary
title_sort millimagnitude photometry for transiting extrasolar planetary candidates. iv. solution to the puzzle of the extremely red ogle-tr-82 primary
publishDate 2007
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v669_n2_p1345_Hoyer
http://hdl.handle.net/20.500.12110/paper_0004637X_v669_n2_p1345_Hoyer
_version_ 1768545719150444544

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