J/AJ/157/33 Radial velocity exploration of ε Eridani (Mawet+, 2019)
Deep exploration of ε Eridani with Keck Ms-band vortex coronagraphy and
radial velocities: mass and orbital parameters of the giant exoplanet.
Mawet D., Hirsch L., Lee E.J., Ruffio J.-B., Bottom M., Fulton B.J.,
Absil O., Beichman C., Bowler B., Bryan M., Choquet E., Ciardi D.,
Christiaens V., Defrere D., Gomez Gonzalez C.A., Howard A.W., Huby E.,
Isaacson H., Jensen-Clem R., Kosiarek M., Marcy G., Meshkat T., Petigura E.,
Reggiani M., Ruane G., Serabyn E., Sinukoff E., Wang J., Weiss L., Ygouf M.
<Astron. J., 157, 33 (2019)>
=2019AJ....157...33M 2019AJ....157...33M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; Stars, dwarfs ; Stars, K-type ; Spectroscopy ;
Radial velocities ; Exoplanets
Keywords: planet-disk interactions -
planets and satellites: dynamical evolution and stability -
planets and satellites: gaseous planets - stars: planetary systems -
techniques: high angular resolution - techniques: radial velocities
Abstract:
We present the most sensitive direct imaging and radial velocity (RV)
exploration of ε Eridani to date. ε Eridani is an
adolescent planetary system, reminiscent of the early solar system. It
is surrounded by a prominent and complex debris disk that is likely
stirred by one or several gas giant exoplanets. The discovery of the RV
signature of a giant exoplanet was announced 15 yr ago, but has met with
scrutiny due to possible confusion with stellar noise. We confirm the
planet with a new compilation and analysis of precise RV data spanning
30 yr, and combine it with upper limits from our direct imaging search,
the most sensitive ever performed. The deep images were taken in the
Ms band (4.7 µm) with the vortex coronagraph recently installed in
W.M. Keck Observatory's infrared camera NIRC2, which opens a sensitive
window for planet searches around nearby adolescent systems. The RV data
and direct imaging upper limit maps were combined in an innovative joint
Bayesian analysis, providing new constraints on the mass and orbital
parameters of the elusive planet. ε Eridani b has a mass of
0.78-0.12+0.38 MJup and is orbiting ε Eridani at about
3.48±0.02 au with a period of 7.37±0.07 yr. The eccentricity of
ε Eridani b's orbit is 0.07-0.05+0.06, an order of magnitude
smaller than early estimates and consistent with a circular orbit. We
discuss our findings from the standpoint of planet-disk interactions and
prospects for future detection and characterization with the James Webb
Space Telescope.
Description:
ε Eridani has been included in planet search programs at both
Keck Observatory using the HIRES Spectrometer (Howard et al.
2010ApJ...721.1467H 2010ApJ...721.1467H) and at Lick Observatory using the Automated Planet
Finder (APF) and Levy Spectrometer. ε Eridani was observed on 206
separate nights with HIRES and the APF, over the past 7 yr.
Keck/HIRES (Vogt et al. 1994SPIE.2198..362V 1994SPIE.2198..362V) RV observations were
obtained starting in 2010, using the standard iodine cell configuration of
the California Planet Survey (CPS) (Howard et al. 2010ApJ...721.1467H 2010ApJ...721.1467H).
During the subsequent 7 yr, 91 observations were taken through the B5 or
C2 deckers (0.87"x3.5", and 0.87"x14", respectively), yielding a spectral
resolution of R∼55000 for each observation. Each RV exposure was timed to
yield a per-pixel S/N of ≳200 at 550 nm, with typical exposure times of
only a few seconds due to the brightness of the target.
RV observations using the APF and Levy Spectrograph (Radovan et al.
2014SPIE.9145E..2BR; Vogt et al. 2014PASP..126..359V 2014PASP..126..359V) were taken starting
in late 2013. The APF is a 2.4 m telescope dedicated to performing RV
detection and follow-up of planets and planet candidates, also using the
iodine cell method of wavelength calibration. APF data on ε Eridani
were primarily taken through the W decker (1"x3"), with a spectral
resolution of R∼110000. Exposures were typically between 10 and 50 s long,
yielding S/N per-pixel of 140.
Objects:
-----------------------------------------------------------
RA (ICRS) DE Designation(s)
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03 32 55.84 -09 27 29.7 ε Eridani = * eps Eri
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 32 91 Keck radial velocity measurements
table6.dat 32 115 APF radial velocity measurements
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See also:
J/ApJ/612/481 : Optical brightness of ε Eri dust ring
(Proffitt+, 2004)
J/ApJ/700/1647 : Search for planetary companions with Spitzer/IRAC
(Marengo+ 2009)
J/ApJ/744/138 : Calibrated visibilities of ε Eri (Baines+, 2012)
J/A+A/552/A78 : Solar like stars radial velocities (Zechmeister+, 2013)
J/ApJ/763/L26 : SMARTS observations of eps Eridani (Metcalfe+, 2013)
J/AJ/154/245 : Imaging survey of Spitzer-detected debris disks
(Meshkat+, 2017)
Byte-by-byte Description of file: table5.dat table6.dat
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Bytes Format Units Label Explanations
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1- 13 F13.5 d JD [2455110.97985/2457830.71979] Julian Date
15- 20 F6.2 m/s RV [-24.97/32.35] Radial velocity (1)
22- 26 F5.2 m/s e_RV [0.51/18.79] The 1σ uncertainty in RV (2)
28- 32 F5.3 --- SHK [0/0.604] The SHK value (3)
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Note (1): The RV data points listed are not offset-subtracted.
Note (2): The uncertainties reflect the internal statistical variance of the
spectral chunks used to extract the RV data points (see Section 2.2 for a full
description). They do not include jitter.
Note (3): A measure of the excess emission at the cores of the Ca II H & K lines
due to chromospheric activity.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 14-May-2019