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

Sergio Hoyer, Sebastián Ramírez Alegría, Valentin D. Ivanov, Dante Minniti, Grzegorz Pietrzyński, María Teresa Ruíz, Wolfgang Gieren, Andrzej Udalski, Manuela Zoccali, Eleazar Rodrigo Carrasco, Rodrigo F. Díaz, José Miguel Fernández, José Gallardo, Marina Rejkuba, Felipe Pérez

Resultado de la investigación: Article

4 Citas (Scopus)

Resumen

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.

Idioma originalEnglish
Páginas (desde-hasta)1345-1353
Número de páginas9
PublicaciónAstrophysical Journal
Volumen669
N.º2
DOI
EstadoPublished - 10 nov 2007

Huella dactilar

Neptune
transit
quantitative analysis
photometry
spectroscopy
metal
stars
telescopes
Neptune (planet)
extremely high frequencies
new technology
comparison
European Southern Observatory
radial velocity
light curve
templates
radii
configurations
metals

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Space and Planetary Science
  • Astronomy and Astrophysics

Citar esto

Hoyer, Sergio ; Alegría, Sebastián Ramírez ; Ivanov, Valentin D. ; Minniti, Dante ; Pietrzyński, Grzegorz ; Ruíz, María Teresa ; Gieren, Wolfgang ; Udalski, Andrzej ; Zoccali, Manuela ; Carrasco, Eleazar Rodrigo ; Díaz, Rodrigo F. ; Fernández, José Miguel ; Gallardo, José ; Rejkuba, Marina ; Pérez, Felipe. / Millimagnitude photometry for transiting extrasolar planetary candidates. IV. Solution to the puzzle of the extremely red OGLE-TR-82 primary. En: Astrophysical Journal. 2007 ; Vol. 669, N.º 2. pp. 1345-1353.
@article{68c5a3fcc6cd4076a1f126a4904d7c5b,
title = "Millimagnitude photometry for transiting extrasolar planetary candidates. IV. Solution to the puzzle of the extremely red OGLE-TR-82 primary",
abstract = "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.",
keywords = "Planets and satellites: formation, Stars: individual (OGLE-TR-82)",
author = "Sergio Hoyer and Alegr{\'i}a, {Sebasti{\'a}n Ram{\'i}rez} and Ivanov, {Valentin D.} and Dante Minniti and Grzegorz Pietrzyński and Ru{\'i}z, {Mar{\'i}a Teresa} and Wolfgang Gieren and Andrzej Udalski and Manuela Zoccali and Carrasco, {Eleazar Rodrigo} and D{\'i}az, {Rodrigo F.} and Fern{\'a}ndez, {Jos{\'e} Miguel} and Jos{\'e} Gallardo and Marina Rejkuba and Felipe P{\'e}rez",
year = "2007",
month = "11",
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doi = "10.1086/520871",
language = "English",
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pages = "1345--1353",
journal = "Astrophysical Journal",
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Hoyer, S, Alegría, SR, Ivanov, VD, Minniti, D, Pietrzyński, G, Ruíz, MT, Gieren, W, Udalski, A, Zoccali, M, Carrasco, ER, Díaz, RF, Fernández, JM, Gallardo, J, Rejkuba, M & Pérez, F 2007, 'Millimagnitude photometry for transiting extrasolar planetary candidates. IV. Solution to the puzzle of the extremely red OGLE-TR-82 primary', Astrophysical Journal, vol. 669, n.º 2, pp. 1345-1353. https://doi.org/10.1086/520871

Millimagnitude photometry for transiting extrasolar planetary candidates. IV. Solution to the puzzle of the extremely red OGLE-TR-82 primary. / Hoyer, Sergio; Alegría, Sebastián Ramírez; Ivanov, Valentin D.; Minniti, Dante; Pietrzyński, Grzegorz; Ruíz, María Teresa; Gieren, Wolfgang; Udalski, Andrzej; Zoccali, Manuela; Carrasco, Eleazar Rodrigo; Díaz, Rodrigo F.; Fernández, José Miguel; Gallardo, José; Rejkuba, Marina; Pérez, Felipe.

En: Astrophysical Journal, Vol. 669, N.º 2, 10.11.2007, p. 1345-1353.

Resultado de la investigación: Article

TY - JOUR

T1 - Millimagnitude photometry for transiting extrasolar planetary candidates. IV. Solution to the puzzle of the extremely red OGLE-TR-82 primary

AU - Hoyer, Sergio

AU - Alegría, Sebastián Ramírez

AU - Ivanov, Valentin D.

AU - Minniti, Dante

AU - Pietrzyński, Grzegorz

AU - Ruíz, María Teresa

AU - Gieren, Wolfgang

AU - Udalski, Andrzej

AU - Zoccali, Manuela

AU - Carrasco, Eleazar Rodrigo

AU - Díaz, Rodrigo F.

AU - Fernández, José Miguel

AU - Gallardo, José

AU - Rejkuba, Marina

AU - Pérez, Felipe

PY - 2007/11/10

Y1 - 2007/11/10

N2 - 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.

AB - 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.

KW - Planets and satellites: formation

KW - Stars: individual (OGLE-TR-82)

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