J/ApJ/759/19 Precise radial velocities of ρ1 Cancri (Endl+, 2012)
Revisiting ρ1 Cancri e: a new mass determination of the transiting
super-Earth.
Endl M., Robertson P., Cochran W.D., MacQueen P.J., Brugamyer E.J.,
Caldwell C., Wittenmyer R.A., Barnes S.I., Gullikson K.
<Astrophys. J., 759, 19 (2012)>
=2012ApJ...759...19E 2012ApJ...759...19E
ADC_Keywords: Planets ; Radial velocities ; Stars, double and multiple
Keywords: planetary systems; stars: individual (* rho1 Cnc, 55 Cnc, HR 3522,
HD 75732); techniques: radial velocities
Abstract:
We present a mass determination for the transiting super-Earth
ρ1 Cancri e based on nearly 700 precise radial velocity (RV)
measurements. This extensive RV data set consists of data collected by
the McDonald Observatory planet search and published data from Lick
and Keck observatories. We obtained 212 RV measurements with the Tull
Coudé Spectrograph at the Harlan J. Smith 2.7m Telescope and
combined them with a new Doppler reduction of the 131 spectra that we
have taken in 2003-2004 with the High-Resolution Spectrograph (HRS) at
the Hobby-Eberly Telescope for the original discovery of ρ1
Cancri e. Using this large data set we obtain a five-planet Keplerian
orbital solution for the system and measure an RV semi-amplitude of
K=6.29±0.21m/s for ρ1 Cnc e and determine a mass of
8.37±0.38M⊕. The uncertainty in mass is thus less than 5%.
This planet was previously found to transit its parent star, which
allowed them to estimate its radius. Combined with the latest radius
estimate from Gillon et al. (Cat. J/A+A/539/A28), we obtain a mean
density of ρ=4.50±0.20g/cm3. The location of ρ1 Cnc e in
the mass-radius diagram suggests that the planet contains a
significant amount of volatiles, possibly a water-rich envelope
surrounding a rocky core.
Description:
We observed ρ1 Cancri as part of the long-term Doppler exoplanet
survey at the Harlan J. Smith 2.7m Telescope (HJST) beginning in 1999
May. For all observations we used the Tull Coude Spectrograph in
combination with a 1.2" slit that yields a resolving power of R=60000
with two-pixel sampling. After 2010, we typically observed ρ1
Cancri several times per month and often up to three times per night.
By 2012 June we collected a total of 212 single exposures, expanding
the total time baseline of the HJST RV data to 4728 days or almost 13
years. See section 2.
We combine these RV measurements with an improved Doppler reduction of
the 131 spectra obtained with the High-Resolution Spectrograph (HRS)
at HET over the time span of 190 days from 2003 October to 2004 April.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
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08 52 35.81 +28 19 51.0 ρ1 Cancri = * rho01 Cnc
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 39 343 Precise radial velocity results
table3.dat 96 5 *Keplerian orbital solutions
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Note on table3.dat: Keplerian orbital solutions for the four giant planets in
the ρ1 Cnc system and for the super-Earth planet ρ1 Cnc e (from
table 2).
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See also:
J/ApJS/210/20 : Small Kepler planets radial velocities (Marcy+, 2014)
J/ApJS/210/5 : The twenty-five year Lick planet search (Fischer+, 2014)
J/A+A/545/A97 : 0.8-6µm calibrated spectrum of 55 Cnc (Crossfield, 2012)
J/A+A/539/A28 : New transit phot. for super-Earth 55 Cnc e (Gillon+, 2012)
J/MNRAS/422/2024 : X-ray-age relation & exoplanet evaporation (Jackson+, 2012)
J/ApJ/733/68 : Exoplanet masses derived from RVs (Brown+, 2011)
J/AJ/142/176 : Exoplanet hosts. II. Speckle interferometry (Mason+, 2011)
J/PASP/123/412 : Exoplanet Orbit Database (Wright+, 2011)
J/A+A/533/A114 : Transit of super-Earth 55 Cnc e (Demory+, 2011)
J/A+A/527/A140 : Mass limits on substellar companions (Reffert+, 2011)
J/other/Sci/330.653 : Detected planets in the Eta-Earth Survey (Howard+, 2010)
J/ApJ/725/2349 : C/O vs Mg/Si of planetary systems (Delgado Mena+, 2010)
J/ApJ/709/168 : Eccentric orbits in exoplanets (Anglada-Escude+, 2010)
J/ApJ/705/1226 : Planet-bearing stars in Spitzer (Bryden+, 2009)
J/ApJ/694/1085 : Radii of exoplanet host stars (van Belle+, 2009)
J/ApJ/693/1084 : Ten new and updated multiplanet systems (Wright+, 2009)
J/ApJ/680/728 : Diameters of exoplanet host stars (Baines+, 2008)
J/ApJ/649/1010 : Habitability of known exoplanetary systems (Jones+, 2006)
J/ApJ/646/505 : Catalog of nearby exoplanets (Butler+, 2006)
J/ApJ/622/1102 : The planet-metallicity correlation. (Fischer+, 2005)
J/A+A/414/351 : ELODIE survey for northern exoplanets III (Naef+, 2004)
J/ApJ/612/511 : Exoplanet radio emission (Lazio+, 2004)
J/ApJ/582/1123 : Search for transiting exoplanets (Mallen-Ornelas+, 2003)
J/A+A/398/363 : Statistical properties of exoplanets II (Santos+, 2003)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 F12.6 d BJD Barycentric Julian Date; (BJD-2400000)
14- 23 F10.3 m/s RVel [-22682.7/28445.6] Differential radial velocity
25- 29 F5.2 m/s e_RVel [1/11.8] Error in RVel
31- 39 A9 --- Tel Telescope/Spectrograph combination used (1)
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Note (1): Telescope/Spectrograph as follows:
HJST/Tull = Harlan J. Smith 2.7m Telescope/Tull Coude Spectrograph;
HET/HRS = Hobby-Eberly Telescope/High-Resolution-Spectrograph.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1 A1 --- Pl Planet designation
3- 13 F11.6 d Per Period
15- 23 F9.6 d e_Per Period uncertainty
25- 29 F5.2 m/s K Semi-amplitude K
31- 34 F4.2 m/s e_K K uncertainty
36- 40 F5.3 --- e Orbit eccentricity
41 A1 --- f_e [f] value set to e=0 (1)
43- 47 F5.3 --- e_e ? e uncertainty
49- 51 I3 deg omega [0/360] Planet's longitude of periastron ω
52 A1 --- f_omega [f] value of omega fixed
54- 55 I2 deg e_omega ? omega uncertainty
57- 63 F7.1 d T0 ? Barycentric Julian Date of periastron passage
(BJD-2400000)
65- 69 F5.1 d e_T0 ? Tper uncertainty
71- 75 F5.3 Mjup Msini ? Minimum mass in Jupiter masses
77- 82 F6.4 Mjup e_Msini ? Msini uncertainty
84- 89 F6.4 AU a ? Planet's orbital radius
91- 96 F6.4 AU e_a ? a uncertainty
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Note (1): We fixed the eccentricity of ρ1 Cnc e to 0 because nearly
circular orbits are expected based on tidal damping
(DF10) and from classic secular theory
(Van Laerhoven & Greenberg 2012CeMDA.113..215V 2012CeMDA.113..215V).
See section 3.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 10-Jul-2014