Astrometric Studies of Aldebaran, Arcturus, Vega, the Hyades, and Other Regions

Gatewood, George

doi:10.1088/0004-6256/136/1/452

Cited by 25 publications

(17 citation statements)

References 35 publications

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“…However, they found a period of 50 days in the line bisector measurements and assumed it to be due to stellar oscillations. Astrometric measurements of Gatewood (2008) could not refute the planet hypothesis of Hatzes & Cochran (1998), though Gatewood (2008) notes that the observed motion is "marginal at best and smaller than suggested by Hatzes & Cochran (1998)". Gatewood (2008) also mentioned that the possible companion is likely to have a mass of 3 to 4 Jovian masses and not as large as the mass of 11 M Jup which Hatzes & Cochran (1998) had derived.…”

Section: Introductionmentioning

confidence: 90%

“…Astrometric measurements of Gatewood (2008) could not refute the planet hypothesis of Hatzes & Cochran (1998), though Gatewood (2008) notes that the observed motion is "marginal at best and smaller than suggested by Hatzes & Cochran (1998)". Gatewood (2008) also mentioned that the possible companion is likely to have a mass of 3 to 4 Jovian masses and not as large as the mass of 11 M Jup which Hatzes & Cochran (1998) had derived. Hatzes et al (2015;hereafter H15) combined data taken between 1980 and 2013 at the Landessternwarte Tautenburg (TLS), the McDonald Observatory (McD), the Canada-France-Hawaii Telescope (CFHT), the Dominion Astrophysical Observatory (DAO), and at the Bohyunsan Optical Astronomy Observatory (BOAO), to re-investigate the nature of the longperiod and long-lived RV variations in Aldebaran.…”

Section: Introductionmentioning

confidence: 90%

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Precise radial velocities of giant stars

Reichert

Reffert

Stock

et al. 2019

A&A

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Context. Radial-velocity variations of the K giant star Aldebaran (α Tau) were first reported in the early 1990s. After subsequent analyses, the radial-velocity variability with a period of ∼629 d has recently been interpreted as caused by a planet of several Jovian masses. Aims. We want to further investigate the hypothesis of an extrasolar planet around Aldebaran. Methods. We combine 165 new radial-velocity measurements from Lick Observatory with seven already published data sets comprising 373 radial-velocity measurements. We perform statistical analyses and investigate whether a Keplerian model properly fits the radial velocities. We also perform a dynamical stability analysis for a possible two-planet solution. Furthermore, the possibility of oscillatory convective modes as cause for the observed radial-velocity variability is discussed. Results. As best Keplerian fit to the combined radial-velocity data we obtain an orbit for the hypothetical planet with a smaller period (P = 607 d) and a larger eccentricity (e = 0.33 ± 0.04) than the previously proposed one. However, the residual scatter around that fit is still large, with a standard deviation of 117 ms−1. In 2006/2007, the statistical power of the ∼620 d period showed a temporary but significant decrease. Plotting the growth of power in reverse chronological order reveals that a period around 620 d is clearly present in the newest data but not in the data taken before ∼2006. Furthermore, an apparent phase shift between radial-velocity data and orbital solution is observable at certain times. A two-planet Keplerian fit matches the data considerably better than a single-planet solution, but poses severe dynamical stability issues. Conclusions. The radial-velocity data from Lick Observatory do not further support but in fact weaken the hypothesis of a substellar companion around Aldebaran. Oscillatory convective modes might be a plausible alternative explanation of the observed radial-velocity variations.

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Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 90%

Precise radial velocities of giant stars

Reichert

Reffert

Stock

et al. 2019

A&A

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“…We used parallaxes from the Hipparcos catalog as well as from Harrington et al (1993) Gatewood (2008); Gatewood & Coban (2009);Khrutskaya, Izmailov & Khovrichev (2010);Riedel et al (2010); Jao et al (2011) andDittmann et al (2014). Some stars are proper motion companions to Hipparcos stars and so have precise parallaxes but no Hipparcos numbers.…”

Section: Catalog Constructionmentioning

confidence: 99%

Trumpeting M dwarfs with CONCH-SHELL: a catalogue of nearby cool host-stars for habitable exoplanets and life

Gaidos

Mann

Lépine

et al. 2014

Monthly Notices of the Royal Astronomical Society

256

189

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We present an all-sky catalog of 2970 nearby (d 50 pc), bright (J < 9) M-or late Ktype dwarf stars, 86% of which have been confirmed by spectroscopy. This catalog will be useful for searches for Earth-size and possibly Earth-like planets by future spacebased transit missions and ground-based infrared Doppler radial velocity surveys. Stars were selected from the SUPERBLINK proper motion catalog according to absolute magnitudes, spectra, or a combination of reduced proper motions and photometric colors. From our spectra we determined gravity-sensitive indices, and identified and removed 0.2% of these as interloping hotter or evolved stars. Thirteen percent of the stars exhibit Hα emission, an indication of stellar magnetic activity and possible youth. The mean metallicity is [Fe/H] = -0.07 with a standard deviation of 0.22 dex, similar to nearby solar-type stars. We determined stellar effective temperatures by least-squares fitting of spectra to model predictions calibrated by fits to stars with established bolometric temperatures, and estimated radii, luminosities, and masses using empirical relations. Six percent of stars with images from integral field spectra are resolved doubles. We inferred the planet population around M dwarfs using Kepler data and applied this to our catalog to predict detections by future exoplanet surveys.

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“…One such example is the temperate Earth-mass planet orbiting Proxima Centauri-b, which is located only 1.2 pc away (Anglada-Escudé et al 2016), while the seven Earth-size planets orbiting the TRAPPIST-1 system at a distance of 12.1 pc, where at least three of them are in the HZ (Gillon et al 2016(Gillon et al , 2017, are equally alluring. In this context, GJ 273 is a highly interesting M dwarf (also known as Luyten's star) hosting a multi-planet system, which is one of the closest stars to the Sun located at only 3.75 pc (Gatewood 2008).…”

Section: Starmentioning

confidence: 99%

GJ 273: on the formation, dynamical evolution, and habitability of a planetary system hosted by an M dwarf at 3.75 parsec

Pozuelos

Suárez

Elía

et al. 2020

A&A

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Context. Planets orbiting low-mass stars such as M dwarfs are now considered a cornerstone in the search for planets with the potential to harbour life. GJ 273 is a planetary system orbiting an M dwarf only 3.75 pc away, which is composed of two confirmed planets, GJ 273b and GJ 273c, and two promising candidates, GJ 273d and GJ 273e. Planet GJ 273b resides in the habitable zone. Currently, due to a lack of observed planetary transits, only the minimum masses of the planets are known: Mb sin ib = 2.89 M⊕, Mc sin ic = 1.18 M⊕, Md sin id = 10.80 M⊕, and Me sin ie = 9.30 M⊕. Despite its interesting character, the GJ 273 planetary system has been poorly studied thus far. Aims. We aim to precisely determine the physical parameters of the individual planets, in particular, to break the mass–inclination degeneracy to accurately determine the mass of the planets. Moreover, we present a thorough characterisation of planet GJ 273b in terms of its potential habitability. Methods. First, we explored the planetary formation and hydration phases of GJ 273 during the first 100 Myr. Secondly, we analysed the stability of the system by considering both the two- and four-planet configurations. We then performed a comparative analysis between GJ 273 and the Solar System and we searched for regions in GJ 273 which may harbour minor bodies in stable orbits, that is, the main asteroid belt and Kuiper belt analogues. Results. From our set of dynamical studies, we find that the four-planet configuration of the system allows us to break the mass–inclination degeneracy. From our modelling results, the masses of the planets are unveiled as: 2.89 ≤ Mb ≤ 3.03 M⊕, 1.18 ≤ Mc ≤ 1.24 M⊕, 10.80 ≤ Md ≤ 11.35 M⊕, and 9.30 ≤ Me ≤ 9.70 M⊕. These results point to a system that is likely to be composed of an Earth-mass planet, a super-Earth and two mini-Neptunes. Based on planetary formation models, we determine that GJ 273b is likely an efficient water captor while GJ 273c is probably a dry planet. We find that the system may have several stable regions where minor bodies might reside. Collectively, these results are used to offer a comprehensive discussion about the habitability of GJ 273b.

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Astrometric Studies of Aldebaran, Arcturus, Vega, the Hyades, and Other Regions

Cited by 25 publications

References 35 publications

Precise radial velocities of giant stars

Precise radial velocities of giant stars

Trumpeting M dwarfs with CONCH-SHELL: a catalogue of nearby cool host-stars for habitable exoplanets and life

GJ 273: on the formation, dynamical evolution, and habitability of a planetary system hosted by an M dwarf at 3.75 parsec

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