Evidence for a Long-Period Planet Orbiting ε Eridani

Hatzes, A. P.; Cochran, William D.; McArthur, B.; Baliunas, S. L.; Walker, G. A. H.; Campbell, B.; Irwin, Alan; Yang, S.; Kürster, M.; Endl, Michael; Els, S.; Butler, R. Paul; Marcy, Geoffrey W.

doi:10.1086/317319

Cited by 244 publications

(207 citation statements)

References 27 publications

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“…With a distance of only 3.7 pc, HD 10700 is the third closest star reported to be a host to a putative planetary system after Eridani (Hatzes et al 2000) with a distance of 3.2 pc and α Centauri B (Dumusque et al 2012) with a distance of 1.3 pc, though both of these remain to be confirmed and Zechmeister et al (2013) have casted considerable doubt on the existence of a planet around Eridani. This makes HD 10700 an ideal target for future direct-imaging missions.…”

Section: Discussionmentioning

confidence: 99%

Signals embedded in the radial velocity noise

Tuomi

Jones

Jenkins

et al. 2013

A&A

125

119

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Context. The abilities of radial velocity exoplanet surveys to detect the lowest-mass extra-solar planets are currently limited by a combination of instrument precision, lack of data, and "jitter". Jitter is a general term for any unknown features in the noise, and reflects a lack of detailed knowledge of stellar physics (asteroseismology, starspots, magnetic cycles, granulation, and other stellar surface phenomena), as well as the possible underestimation of instrument noise. Aims. We study an extensive set of radial velocities for the star HD 10700 (τ Ceti) to determine the properties of the jitter arising from stellar surface inhomogeneities, activity, and telescope-instrument systems, and perform a comprehensive search for planetary signals in the radial velocities. Methods. We performed Bayesian comparisons of statistical models describing the radial velocity data to quantify the number of significant signals and the magnitude and properties of the excess noise in the data. We reached our goal by adding artificial signals to the "flat" radial velocity data of HD 10700 and by seeing which one of our statistical noise models receives the greatest posterior probabilities while still being able to extract the artificial signals correctly from the data. We utilised various noise components to assess properties of the noise in the data and analyse the HARPS, AAPS, and HIRES data for HD 10700 to quantify these properties and search for previously unknown low-amplitude Keplerian signals.Results. According to our analyses, moving average components with an exponential decay with a timescale from a few hours to few days, and Gaussian white noise explains the jitter the best for all three data sets. Fitting the corresponding noise parameters results in significant improvements of the statistical models and enables the detection of very weak signals with amplitudes below 1 m s −1 level in our numerical experiments. We detect significant periodicities that have no activity-induced counterparts in the combined radial velocities. Three of these signals can be seen in the HARPS data alone, and a further two can be inferred by utilising the AAPS and Keck data. These periodicities could be interpreted as corresponding to planets on dynamically stable close-circular orbits with periods of 13.9, 35.4, 94, 168, and 640 days and minimum masses of 2.0, 3.1, 3.6, 4.3, and 6.6 M ⊕ , respectively.

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Section: Discussionmentioning

confidence: 99%

Signals embedded in the radial velocity noise

Tuomi

Jones

Jenkins

et al. 2013

A&A

125

119

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“…It is believed to be a relatively young system (<1 Gyr; Song et al 2000;Soderblom & Dappen 1989), with a mass slightly less than our own Sun. From radial velocity measurements, Hatzes et al (2000) have reported evidence for a planet in this system with a semimajor axis of 3.4 AU and m sin i ¼ 0:86M J .…”

Section: Introductionmentioning

confidence: 87%

Limits on the Optical Brightness of the ε Eridani Dust Ring

Proffitt

Sahu

Livio

et al. 2004

ApJ

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The STIS CCD camera on the Hubble Space Telescope (HST ) was used to take deep optical images near the K2 V main-sequence star Eridani in an attempt to find an optical counterpart of the dust ring previously imaged by submillimeter observations. Upper limits for the optical brightness of the dust ring are determined and discussed in the context of the scattered starlight expected from plausible dust models. We find that even if the dust is smoothly distributed in symmetrical rings, the optical surface brightness of the dust, as measured with the HST STIS CCD clear aperture at 55 AU from the star, cannot be brighter than about 25 STMAG arcsec À2 . This upper limit excludes some solid-grain models for the dust ring that can fit the IR and submillimeter data. Magnitudes and positions for %59 discrete objects between 12B5 and 58 00 from Eri are reported. Most if not all of these objects are likely to be background stars and galaxies.

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“…We have used the robust radial velocity fit from Hatzes et al (2000) as an input for our astrometric fit to the Hipparcos intermediate astrometric data. Formally the fit from Benedict et al (2006) would have been the most precise one, but we preferred input parameters that came from a spectroscopic fit only instead of one which already was based on combined spectroscopy and HST astrometry.…”

Section: Eri (Hip 16537)mentioning

confidence: 99%

Mass constraints on substellar companion candidates from the re-reducedHipparcosintermediate astrometric data: nine confirmed planets and two confirmed brown dwarfs

Reffert¹,

Quirrenbach²

2011

A&A

106

107

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Context. The recently completed re-reduction of the Hipparcos data by van Leeuwen (2007a, Astrophysics and Space Science Library, 350) makes it possible to search for the astrometric signatures of planets and brown dwarfs known from radial velocity surveys in the improved Hipparcos intermediate astrometric data. Aims. Our aim is to put more significant constraints on the orbital parameters which cannot be derived from radial velocities alone, i.e. the inclination and the longitude of the ascending node, than was possible before. The determination of the inclination in particular allows to calculate an unambiguous companion mass, rather than the lower mass limit which can be obtained from radial velocity measurements. Methods. We fitted the astrometric orbits of 310 substellar companions around 258 stars, which were all discovered via the radial velocity method, to the Hipparcos intermediate astrometric data provided by van Leeuwen. Results. Even though the astrometric signatures of the companions cannot be detected in most cases, the Hipparcos data still provide lower limits on the inclination for all but 67 of the investigated companions, which translates into upper limits on the masses of the unseen companions. For nine companions the derived upper mass limit lies in the planetary and for 75 companions in the brown dwarf mass regime, proving the substellar nature of those objects. Two of those objects have minimum masses also in the brown dwarf regime and are thus proven to be brown dwarfs. . Of the others, many are either brown dwarfs or very low mass stars. For Eri, we derive a solution which is very similar to the one obtained using Hubble Space Telescope data.

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Evidence for a Long-Period Planet Orbiting ε Eridani

Cited by 244 publications

References 27 publications

Signals embedded in the radial velocity noise

Signals embedded in the radial velocity noise

Limits on the Optical Brightness of the ε Eridani Dust Ring

Mass constraints on substellar companion candidates from the re-reducedHipparcosintermediate astrometric data: nine confirmed planets and two confirmed brown dwarfs

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