J/ApJS/200/15 HARPS-TERRA project. I. (Anglada-Escude+, 2012)
The HARPS-TERRA project.
I. Description of the algorithms, performance, and new measurements on a few
remarkable stars observed by HARPS.
Anglada-Escude G., Butler R.P.
<Astrophys. J. Suppl. Ser., 200, 15 (2012)>
=2012ApJS..200...15A 2012ApJS..200...15A
ADC_Keywords: Radial velocities ; Stars, M-type ; Planets ; Spectroscopy ;
Stars, double and multiple
Keywords: methods: data analysis - planetary systems -
stars: individual (Tau Ceti, HD 85512, Barnard's star, Proxima,
Kapteyn's star, GJ676A, Epsilon Eridani, HD 69830) -
techniques: radial velocities
Abstract:
Doppler spectroscopy has uncovered or confirmed all the known planets
orbiting nearby stars. Two main techniques are used to obtain
precision Doppler measurements at optical wavelengths. The first
approach is the gas cell method, which consists of least-squares
matching of the spectrum of iodine imprinted on the spectrum of the
star. The second method relies on the construction of a stabilized
spectrograph externally calibrated in wavelength. The most precise
stabilized spectrometer in operation is the High Accuracy Radial
velocity Planet Searcher (HARPS), operated by the European Southern
Observatory in La Silla Observatory, Chile. The Doppler measurements
obtained with HARPS are typically obtained using the cross-correlation
function (CCF) technique. This technique consists of multiplying the
stellar spectrum by a weighted binary mask and finding the minimum of
the product as a function of the Doppler shift. It is known that CCF
is suboptimal in exploiting the Doppler information in the stellar
spectrum. Here we describe an algorithm to obtain precision radial
velocity measurements using least-squares matching of each observed
spectrum to a high signal-to-noise ratio template derived from the
same observations. This algorithm is implemented in our software
HARPS-TERRA (Template-Enhanced Radial velocity Re-analysis
Application). New radial velocity measurements on a representative
sample of stars observed by HARPS are used to illustrate the benefits
of the proposed method. We show that, compared with CCF, template
matching provides a significant improvement in accuracy, especially
when applied to M dwarfs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 68 9 List of the stars studied (from table2 of paper)
table5.dat 79 344 Differential RV and S-index measurements for
τ Cet, HD 85512, GJ 676A, and ε Eri
table6.dat 80 79 RV measurements for Barnard's Star,
Kapteyn's Star, and Proxima Cen
table7.dat 66 527 Measurements on HD 69830
table10.dat 38 184 Differential RV measurements on GJ 667C used in
Anglada-Escude et al. (2012ApJ...751L..16A 2012ApJ...751L..16A)
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See also:
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
III/185 : Search for Jupiter-Mass Companions (Walker+, 1995)
J/A+A/541/A9 : M dwarfs activity and radial velocity (Gomes da Silva+, 2012)
J/A+A/534/A58 : HD20794, HD85512, HD192310 HARPS RVs (Pepe+, 2011)
J/A+A/527/A140 : Mass limits on substellar companions (Reffert+, 2011)
J/A+A/526/A141 : Velocity of Gl 676A and HIP 12961 (Forveille+, 2011)
J/A+A/534/A133 : Proxima Cen chromospheric emission lines (Fuhrmeister+, 2011)
J/other/Sci/330.653 : Detected planets in the Eta-Earth Survey (Howard+, 2010)
J/A+A/505/859 : M dwarfs radial velocities (Zechmeister+, 2009)
J/A+A/487/373 : Spectroscopic parameters of 451 HARPS-GTO stars (Sousa+, 2008)
J/ApJ/646/505 : Catalog of nearby exoplanets (Butler+, 2006)
J/ApJS/141/503 : Radial Velocities for 889 late-type stars (Nidever+, 2002)
J/A+A/325/159 : Companions to M dwarfs within 5pc (Leinert+ 1997)
http://archive.eso.org/wdb/wdb/eso/repro/form : FEROS/HARPS data query form
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Simbad name
17- 18 I2 h RAh Simbad Hour of Right Ascension (J2000.0)
20- 21 I2 min RAm Simbad Minute of Right Ascension (J2000.0)
23- 27 F5.2 s RAs Simbad Second of Right Ascension (J2000.0)
29 A1 --- DE- Simbad Sign of the Declination (J2000.0)
30- 31 I2 deg DEd Simbad Degree of Declination (J2000.0)
33- 34 I2 arcmin DEm Simbad Arcminute of Declination (J2000.0)
36- 39 F4.1 arcsec DEs Simbad Arcsecond of Declination (J2000.0)
41- 45 F5.2 mag Vmag Simbad V band magnitude
47- 51 F5.2 mag Kmag Simbad K band magnitude
53- 57 A5 --- SpType Simbad MK spectral type
60- 61 I2 --- Tab [5/10] Number of table with RV data
63- 68 F6.1 d Per ? Orbital period
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Star identifier (1)
13- 26 F14.6 d JD Julian Date of the observation
28- 37 F10.5 m/s RV Differential TERRA radial velocity
39- 45 F7.5 m/s e_RV Error in RV
47- 55 F9.5 m/s RVCCF Differential CCF radial velocity
57- 63 F7.5 m/s e_RVCCF Error in RVCCF
65- 71 F7.5 --- SMW Mt. Wilson S-index activity measurement
73- 79 F7.5 --- e_SMW Error in SMW
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Note (1): For 34 epochs of GJ 676A.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Star identifier (1)
16- 29 F14.6 d JD Julian Date of the observation
31- 38 F8.5 m/s RV Differential TERRA radial velocity
40- 46 F7.5 m/s e_RV Error in RV
48- 55 F8.5 m/s RVCCF Differential CCF radial velocity
57- 63 F7.5 m/s e_RVCCF Error in RVCCF
65- 72 F8.5 m/s RVRed Differential TERRA red radial velocity (2)
74- 80 F7.5 m/s e_RVRed Error in RVRed
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Note (1): Identifier as follows:
Barnard's star = GJ 699 (6000<λ<6800 Angstroms);
Kapteyn's star = GJ 191 (4670<λ<6800 Angstroms);
Proxima Cen = GJ 551 (4400<λ<6800 Angstroms).
Note (2): The RV measurements obtained using the optimal redmost part of the
spectrum only, see Section 3.2 and Note (1) for wavelength ranges.
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d JD Julian Date of the observation
16- 23 F8.5 m/s RV Differential TERRA radial velocity
25- 32 F8.5 m/s e_RV Error in RV
34- 41 F8.5 m/s RVRed Differential TERRA red radial velocity (1)
43- 50 F8.5 m/s e_RVRed Error in RVRed
52- 58 F7.5 --- SMW Mt Wilson S-index activity measurement
60- 66 F7.5 --- e_SMW Error in SMW
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Note (1): Instead of the CCF RVs, RV using the redder part of the spectrum
(see Section 4.4.1) are provided in this case.
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Byte-by-byte Description of file: table10.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Inst Instrument: HARPS, PFS or HIRES
7- 20 F14.6 d JD Julian Date of the observation
22- 29 F8.4 m/s RV Differential radial velocity
33- 38 F6.4 m/s e_RV ? Error in RV
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 17-Jul-2012