And the Oscar Goes to: BD+20 1790 for “The Mystery of the Unseen Companion“

Hernán‐Obispo, M.; Gálvez, M. C.; Anglada-Escudé, G.; Kane, Stephen R.; Castro, E. de; Cornide, M.

doi:10.1007/978-3-642-11250-8_105

Cited by 3 publications

(8 citation statements)

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“…The corotation radius for BD+20 1790 is up to 10 R * . Due to the inclination of the star (i ∼ 50 o , Hernán-Obispo et al 2010), the prominence-like structures detected by Hernán-Obispo et al (2005), may be located significantly above the equatorial planet to transit the stellar disc, at high latitude, and at a height of about 15 R * determined following Collier Cameron & Robinson (1989a). The pronounced double horned peaks that exhibit the Hα emission line is a shape typical of emission from circumstellar material at high latitude, that is varying with time (Barnes et al 2001).…”

Section: Discussionmentioning

confidence: 90%

“…Main properties are detailed at Table 1. In our previous studies (Hernán-Obispo et al 2005, López-Santiago et al 2006, BD+20 1790 shows a high level of stellar activity that is manifested in a plethora of phenomena at different atmospheric layers. We detected strong chromospheric emission, as suggested by all the chromospheric activity indicators being in emission above continuum (from Ca ii H & K to Ca ii infrared triplet).…”

Section: Bd+20 1790 System: Previous Workmentioning

confidence: 85%

“…Prominence-like structures were detected at latitudes far from the equatorial plane (Hernán-Obispo et al 2005), as well as plage-like structures. From the modulation of the photometric light curve we reported the presence of photospheric spots, with a mean spot filling factor ( f s hereafter) up to 9%.…”

Section: Bd+20 1790 System: Previous Workmentioning

confidence: 94%

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Analysis of combined radial velocities and activity of BD+20 1790: evidence supporting the existence of a planetary companion

Hernán‐Obispo

Tuomi

Gálvez-Ortiz

et al. 2015

A&A

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Context. In a previous paper we reported a planetary companion to the young and very active K5Ve star BD+20 1790. We found that this star has a high level of stellar activity (log R HK = −3.7) that manifests in a plethora of phenomena (starspots, prominences, plages, large flares). Based on a careful study of these activity features and a deep discussion and analysis of the effects of the stellar activity on the radial velocity measurements, we demonstrated that the presence of a planet provided the best explanation for the radial velocity variations and all the peculiarities of this star. The orbital solution resulted in a close-in massive planet with a period of 7.78 days. However, a paper by Figueira et al. (2010, A&A, 513, L8) questioned the evidence for the planetary companion. Aims. This paper aims to more rigorously assess the nature of the radial velocity measurements with an expanded data set and new methods of analysis. Methods. We have employed Bayesian methods to simultaneously analyse the radial velocity and activity measurements based on a combined data set that includes new and previously published observations. Results. We conclude that the Bayesian analysis and the new activity study support the presence of a planetary companion to BD+20 1790. A new orbital solution is presented, after removing the two main contributions of stellar jitter, one that varies with the photometric period (2.8 days) and another that varies with the synodic period of the star-planet system (4.36 days). We present a new method to determine these jitter components, considering them as second and third signals in the system. A discussion on possible star-planet interaction is included, based on the Bayesian analysis of the activity indices, which indicates that they modulate with the synodic period. We propose two different sources for flare events in this system: one related to the geometry of the system and the relative movement of the star and planet, and a second one purely stochastic source that is related to the evolution of stellar surface active regions. Also, we observe for the first time the magnetic field of the star, from spectropolarimetric data.

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Section: Discussionmentioning

confidence: 90%

Section: Bd+20 1790 System: Previous Workmentioning

confidence: 85%

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Analysis of combined radial velocities and activity of BD+20 1790: evidence supporting the existence of a planetary companion

Hernán‐Obispo

Tuomi

Gálvez-Ortiz

et al. 2015

A&A

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“…In order to study the stellar activity, our group has been carried out a spectroscopic monitoring with high temporal and spectral resolution and two-band photometry. Strong chromospheric activity was detected in several observing runs, described by Hernán-Obispo [2], [3]. In spite of the fact that the rotational velocity of BD+20 1790 is not very high (vsini ∼10 km s −1 ), all activity indicators are in emission, from Ca II H & K to Ca II IRT lines including all Balmer lines.…”

Section: Bd+20 1790: Chromospheric and Photospheric Activitymentioning

confidence: 93%

“…Through the study of profile line asymmetries of Hα and Hβ , prominence-like structures have been detected in the chromosphere of the star [2,3]. In addition, strong flare events were observed (Fig.…”

Section: Bd+20 1790: Chromospheric and Photospheric Activitymentioning

confidence: 95%

BD+20 1790 b: Chronicle of an exoplanetary discovery

Hernán‐Obispo¹,

Gálvez²,

Anglada‐Escudé³

et al. 2009

AIP Conference Proceedings

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Evidence of a massive planet candidate orbiting the young active K5V star BD+20 1790

Hernán‐Obispo

Gálvez-Ortiz

Anglada-Escudé

et al. 2010

A&A

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Context. BD+20 1790 is a young active, metal-rich, late-type K5Ve star. We have undertaken a study of stellar activity and kinematics for this star over the past few years. Previous results show a high level of stellar activity, with the presence of prominence-like structures, spots on the surface and strong flare events, despite the moderate rotational velocity of the star. In addition, radial velocity variations with a semi-amplitude of up to 1 km s −1 were detected. Aims. We investigated the nature of these radial velocity variations, in order to determine whether they are due to stellar activity or the reflex motion of the star induced by a companion. Methods. We have analysed high-resolution echelle spectra, by measuring stellar activity indicators, and computing radial velocity (RV) and bisector velocity spans. Also two-band photometry was obtained to produce the light curve and determine the photometric period.Results. Based upon the analysis of the bisector velocity span, as well as spectroscopic indices of chromospheric indicators, like e.g. Ca II H & K, Hα, and taking into account the photometric analysis, we report that the best explanation for the RV variation is the presence of a sub-stellar companion. The Keplerian fit of the RV data yields a solution for a close-in massive planet with an orbital period of 7.78 days. The presence of the close-in massive planet could also be an interpretation for the high level of stellar activity detected. Since the RV data are not part of a planet search program, we can consider our results as a serendipitous evidence of a planetary companion. To date, this is the youngest main sequence star for which a planetary candidate has been reported.

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And the Oscar Goes to: BD+20 1790 for “The Mystery of the Unseen Companion“

Cited by 3 publications

References 1 publication

Analysis of combined radial velocities and activity of BD+20 1790: evidence supporting the existence of a planetary companion

Analysis of combined radial velocities and activity of BD+20 1790: evidence supporting the existence of a planetary companion

BD+20 1790 b: Chronicle of an exoplanetary discovery

Evidence of a massive planet candidate orbiting the young active K5V star BD+20 1790

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