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ABSTRACT: We present radial velocities with an accuracy of 0.1 km/s for 2046 stars of
spectral type F,G,K, and M, based on 29000 spectra taken with the Keck I
telescope. We also present 131 FGKM standard stars, all of which exhibit
constant radial velocity for at least 10 years, with an RMS less than 0.03
km/s. All velocities are measured relative to the solar system barycenter.
Spectra of the Sun and of asteroids pin the zero-point of our velocities,
yielding a velocity accuracy of 0.01 km/s for G2V stars. This velocity
zero-point agrees within 0.01 \kms with the zero-points carefully determined by
Nidever et al. (2002) and Latham et al. (2002). For reference we compute the
differences in velocity zero-points between our velocities and standard stars
of the IAU, the Harvard-Smithsonian Center for Astrophysics, and l'Observatoire
de Geneve, finding agreement with all of them at the level of 0.1 km/s. But our
radial velocities (and those of all other groups) contain no corrections for
convective blueshift or gravitational redshifts (except for G2V stars), leaving
them vulnerable to systematic errors of 0.2 \kms for K dwarfs and ~0.3 km/s for
M dwarfs due to subphotospheric convection, for which we offer velocity
corrections. The velocities here thus represent accurately the radial component
of each star's velocity vector. The radial velocity standards presented here
are designed to be useful as fundamental standards in astronomy. They may be
useful for Gaia (Crifo et al. 2010, Gilmore et al. 2012} and for dynamical
studies of such systems as long-period binary stars, star clusters, Galactic
structure, and nearby galaxies, as will be carried out by SDSS, RAVE, APOGEE,
SkyMapper, HERMES, and LSST.
07/2012;
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ABSTRACT: We determine the fraction of F, G, and K dwarfs in the Solar Neighborhood
hosting hot jupiters as measured by the California Planet Survey from the Lick
and Keck planet searches. We find the rate to be 1.2\pm0.38%, which is
consistent with the rate reported by Mayor et al. (2011) from the HARPS and
CORALIE radial velocity surveys. These numbers are more than double the rate
reported by Howard et al. (2011) for Kepler stars and the rate of Gould et al.
(2006) from the OGLE-III transit search, however due to small number statistics
these differences are of only marginal statistical significance. We explore
some of the difficulties in estimating this rate from the existing radial
velocity data sets and comparing radial velocity rates to rates from other
techniques.
05/2012;
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J. T. Wright,
Dimitri Veras,
Eric B. Ford,
John Asher Johnson,
G. W. Marcy,
A. W. Howard,
H. Isaacson,
D. A. Fischer,
J. Spronck,
J. Anderson,
and J. Valenti
[show abstract]
[hide abstract]
ABSTRACT: We present new radial velocities from Keck Observatory and both Newtonian and Keplerian solutions for the triple-planet system orbiting HD 37124. The orbital solution for this system has improved dramatically since the third planet was first reported in Vogt et al. with an ambiguous orbital period. The period ambiguity is resolved, and the outer two planets have an apparent period commensurability of 2:1. A dynamical analysis finds both resonant and non-resonant configurations consistent with the radial velocity data and constrains the mutual inclinations of the planets to be <~30°. We discuss HD 37124 in the context of the other 19 exoplanetary systems with apparent period commensurabilities, which we summarize in a table. We show that roughly one in three well-characterized multiplanet systems has a apparent low-order period commensurability, which is more than would naïvely be expected if the periods of exoplanets in known multiplanet systems were drawn randomly from the observed distribution of planetary orbital periods.
The Astrophysical Journal 03/2011; 730(2):93. · 6.02 Impact Factor
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ABSTRACT: We present two exoplanets detected at Keck Observatory. HD 179079 is a G5 subgiant that hosts a hot Neptune planet with Msini = 27.5 M_earth in a 14.48 d, low-eccentricity orbit. The stellar reflex velocity induced by this planet has a semiamplitude of K = 6.6 m/s. HD 73534 is a G5 subgiant with a Jupiter-like planet of Msini = 1.1 M_jup and K = 16 m/s in a nearly circular 4.85 yr orbit. Both stars are chromospherically inactive and metal-rich. We discuss a known, classical bias in measuring eccentricities for orbits with velocity semiamplitudes, K, comparable to the radial velocity uncertainties. For exoplanets with periods longer than 10 days, the observed exoplanet eccentricity distribution is nearly flat for large amplitude systems (K > 80 m/s), but rises linearly toward low eccentricity for lower amplitude systems (K > 20 m/s). Comment: 8 figures, 6 tables, accepted, ApJ
08/2009;
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D. A. Fischer,
P. Driscoll,
H. Isaacson,
M. Giguere,
G. W. Marcy,
J. A. Valenti, J. T. Wright,
G. W. Henry,
J A Johnson,
A. W. Howard,
K. M. G. Peek,
C McCarthy
[show abstract]
[hide abstract]
ABSTRACT: We present time series Doppler data from Lick Observatory that reveal the presence of long-period planetary companions orbiting nearby stars. The typical eccentricity of these massive planets are greater than the mean eccentricity of known exoplanets. HD30562b has Msini = 1.29 Mjup, with semi-major axis of 2.3 AU and eccentricity 0.76. The host star has a spectral type F8V and is metal rich. HD86264b has Msini = 7.0 Mjup, arel = 2.86 AU, an eccentricity, e = 0.7 and orbits a metal-rich, F7V star. HD87883b has Msini = 1.78 Mjup, arel = 3.6 AU, e = 0.53 and orbits a metal-rich K0V star. HD89307b has Msini = 1.78 Mjup, arel = 3.3 AU, e = 0.24 and orbits a G0V star with slightly subsolar metallicity. HD148427b has Msini = 0.96 Mjup, arel = 0.93 AU, eccentricity of 0.16 and orbits a metal rich K0 subgiant. We also present velocities for a planet orbiting the F8V metal-rich binary star, HD196885A. The planet has Msini = 2.58 Mjup, arel = 2.37 AU, and orbital eccentricity of 0.48, in agreement with the independent discovery by Correia et al. 2008. Comment: 12 figures, 8 tables, accepted ApJ
08/2009;
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[show abstract]
[hide abstract]
ABSTRACT: We present new precision radial velocities and a three-planet Keplerian orbit fit for the V = 8.5, G5 V star HIP 14810. We began observing this star at Keck Observatory as part of the N2K Planet Search Project. Wright et al. announced the inner two planets to this system, and subsequent observations have revealed the outer planet and the proper orbital solution for the middle planet. The planets have minimum masses of 3.9, 1.3, and 0.6 M Jup and orbital periods of 6.67, 147.7, and 952 day, respectively. We have numerically integrated the family of orbital solutions consistent with the data and find that they are stable for at least 106 yr. Our photometric search shows that the inner planet does not transit.
The Astrophysical Journal 06/2009; 699(2):L97. · 6.02 Impact Factor
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ABSTRACT: We describe a technique for solving for the orbital elements of multiple planets from radial velocity (RV) and/or astrometric data taken with 1 m/s and microarcsecond precision, appropriate for efforts to detect Earth-massed planets in their stars' habitable zones, such as NASA's proposed Space Interferometry Mission. We include details of calculating analytic derivatives for use in the Levenberg-Marquardt (LM) algorithm for the problems of fitting RV and astrometric data separately and jointly. We also explicate the general method of separating the linear and nonlinear components of a model fit in the context of an LM fit, show how explicit derivatives can be calculated in such a model, and demonstrate the speed up and convergence improvements of such a scheme in the case of a five-planet fit to published radial velocity data for 55 Cnc. Comment: ApJS accepted
04/2009;
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[show abstract]
[hide abstract]
ABSTRACT: We present the latest velocities for ten multiplanet systems, including a re-analysis of archival Keck and Lick data, resulting in improved velocities that supersede our previously published measurements. We derive updated orbital fits for 10 Lick and Keck systems, including two systems (HD 11964, HD 183263) for which we provide confirmation of second planets only tentatively identified elsewhere, and two others (HD 187123 and HD 217107) for which we provide a major revision of the outer planet's orbit. We compile orbital elements from the literature to generate a catalog of the 28 published multiple-planet systems around stars within 200 pc. From this catalog we find several intriguing patterns emerging: (1) including those systems with long-term radial velocity trends, at least 28% of known planetary systems appear to contain multiple planets; (2) planets in multiple-planet systems have somewhat smaller eccentricities than single planets; and (3) the distribution of orbital distances of planets in multiplanet systems and single planets are inconsistent: single-planet systems show a pileup at P ~ 3 days and a jump near 1 AU, while multiplanet systems show a more uniform distribution in log-period. In addition, among all planetary systems we find the following. (1) There may be an emerging, positive correlation between stellar mass and giant-planet semimajor axis. (2) Exoplanets with M sin i > 1 M Jup more massive than Jupiter have eccentricities broadly distributed across 0 < e < 0.5, while lower mass exoplanets exhibit a distribution peaked near e = 0.
The Astrophysical Journal 03/2009; 693(2):1084. · 6.02 Impact Factor
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R. P. Butler, J. T. Wright,
G. W. Marcy,
D. A. Fischer,
S. S. Vogt,
C. G. Tinney,
H. R. A. Jones,
B. D. Carter,
J. A. Johnson,
C. McCarthy,
and A. J. Penny
[show abstract]
[hide abstract]
ABSTRACT: We present a catalog of nearby exoplanets. It contains the 172 known low-mass companions with orbits established through radial velocity and transit measurements around stars within 200 pc. We include five previously unpublished exoplanets orbiting the stars HD 11964, HD 66428, HD 99109, HD 107148, and HD 164922. We update orbits for 83 additional exoplanets, including many whose orbits have not been revised since their announcement, and include radial velocity time series from the Lick, Keck, and Anglo-Australian Observatory planet searches. Both these new and previously published velocities are more precise here due to improvements in our data reduction pipeline, which we applied to archival spectra. We present a brief summary of the global properties of the known exoplanets, including their distributions of orbital semimajor axis, minimum mass, and orbital eccentricity.
The Astrophysical Journal 12/2008; 646(1):505. · 6.02 Impact Factor
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ABSTRACT: We announce the discovery of a twin of Jupiter orbiting the slightly metal-poor ([Fe/H] = − 0.1) nearby (d = 18 pc) G8 dwarf HD 154345. This planet has a minimum mass of 0.95 MJup and a 9.2 year, circular orbit with radius 4.2 AU. There is currently little or no evidence for other planets in the system, but smaller or exterior planets cannot yet be ruled out. We also detect a ~ 9 year activity cycle in this star photometrically and in chromospheric emission. We rule out activity cycles as the source of the radial velocity variations by comparison with other cycling late G dwarfs.
The Astrophysical Journal 12/2008; 683(1):L63. · 6.02 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We present the latest velocities for 10 multi-planet systems, including a
re-analysis of archival Keck and Lick data, resulting in improved velocities
that supersede our previously published measurements. We derive updated orbital
fits for ten Lick and Keck systems, including two systems (HD 11964, HD 183263)
for which we provide confirmation of second planets only tentatively identified
elsewhere, and two others (HD 187123, and HD 217107) for which we provide a
major revision of the outer planet's orbit. We compile orbital elements from
the literature to generate a catalog of the 28 published multiple-planet
systems around stars within 200 pc. From this catalog we find several
intriguing patterns emerging: - Including those systems with long-term radial
velocity trends, at least 28% of known planetary systems appear to contain
multiple planets. - Planets in multiple-planet systems have somewhat smaller
eccentricities than single planets. - The distribution of orbital distances of
planets in multi-planet systems and single planets are inconsistent:
single-planet systems show a pile-up at P ~ 3 days and a jump near 1 AU, while
multi-planet systems show a more uniform distribution in log-period. In
addition, among all planetary systems we find: - There may be an emerging,
positive correlation between stellar mass and giant-planet semi-major axis. -
Exoplanets more massive than Jupiter have eccentricities broadly distributed
across 0 < e < 0.5, while lower-mass exoplanets exhibit a distribution peaked
near e = 0.
12/2008;
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G W Marcy,
R P Butler,
S S Vogt,
D A Fischer, J T Wright,
J A Johnson,
C G Tinney,
H R A Jones,
B D Carter,
J Bailey,
S J O'Toole,
S Upadhyay
[show abstract]
[hide abstract]
ABSTRACT: Doppler-shift measurements with a remarkable precision of Δλ/λ=3×10−9, corresponding to velocities of 1 m s−1, have been made repeatedly of 2500 stars located within 300 light years. The observed gravitational perturbations of the stars have revealed 250 orbiting planets, with 27 that cross in front of the host star, blocking a fraction of the starlight to allow measurement of the planet's mass, radius and density. Two new discoveries are the first good analog of Jupiter (HD 154345b) and the first system of five planets (55 Cancri). The predominantly eccentric orbits of exoplanets probably result from planet–planet gravitational interactions or angular momentum exchange by mean-motion resonances. The planet mass distribution ranges from ~15 MJUP to as low as ~5 MEarth and rises toward lower masses as dN/dM∝M−1.1. The distribution with orbital distance, a, rises (in logarithmic intervals) as dN/d log a∝a+0.4. Extrapolation and integration suggests that 19% of all Sun-like stars harbor a gas-giant planet within 20 AU, but there remains considerable incompleteness for large orbits. Beyond 20 AU, the occurrence of gas-giant planets may be less than a few per cent as protoplanetary disk material there has lower densities and is vulnerable to destruction. Jupiter-mass planets occur more commonly around more massive stars than low mass stars. The transit of the Neptune-mass planet, Gliese 436b, yields a density of 1.55 g cm−3 suggesting that its interior has an iron–silicate core surrounded by an envelope of water–ice and an outer H–He shell. Planets with masses as low as five Earth-masses may be commonly composed of iron–nickel, rock and water along with significant amounts of H and He, making the term 'super-Earth' misleading. The transiting planet HD147506b has high orbital eccentricity but no significant orbital inclination to the line of sight, presenting a puzzle about its history. Its orbit together with the mean motion resonances of 4 of the 22 multi-planet systems provides further evidence for the role of planet–planet interactions in shaping planetary architectures.
Physica Scripta 07/2008; 2008(T130):014001. · 1.20 Impact Factor
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G W Marcy,
R P Butler,
S S Vogt,
D A Fischer, J T Wright,
J A Johnson,
C G Tinney,
H R A Jones,
B D Carter,
J Bailey,
O ' Toole,
S Upadhyay
[show abstract]
[hide abstract]
ABSTRACT: Doppler-shift measurements with a remarkable precision of λ/λ = 3 × 10 −9 , corresponding to velocities of 1 m s −1 , have been made repeatedly of 2500 stars located within 300 light years. The observed gravitational perturbations of the stars have revealed 250 orbiting planets, with 27 that cross in front of the host star, blocking a fraction of the starlight to allow measurement of the planet's mass, radius and density. Two new discoveries are the first good analog of Jupiter (HD 154345b) and the first system of five planets (55 Cancri). The predominantly eccentric orbits of exoplanets probably result from planet–planet gravitational interactions or angular momentum exchange by mean-motion resonances. The planet mass distribution ranges from ∼ 15 M JUP to as low as ∼ 5 M Earth and rises toward lower masses as dN /dM ∝ M −1.1 . The distribution with orbital distance, a, rises (in logarithmic intervals) as dN /d log a ∝ a +0.4 . Extrapolation and integration suggests that 19% of all Sun-like stars harbor a gas-giant planet within 20 AU, but there remains considerable incompleteness for large orbits. Beyond 20 AU, the occurrence of gas-giant planets may be less than a few per cent as protoplanetary disk material there has lower densities and is vulnerable to destruction. Jupiter-mass planets occur more commonly around more massive stars than low mass stars. The transit of the Neptune-mass planet, Gliese 436b, yields a density of 1.55 g cm −3 suggesting that its interior has an iron–silicate core surrounded by an envelope of water–ice and an outer H–He shell. Planets with masses as low as five Earth-masses may be commonly composed of iron–nickel, rock and water along with significant amounts of H and He, making the term 'super-Earth' misleading. The transiting planet HD147506b has high orbital eccentricity but no significant orbital inclination to the line of sight, presenting a puzzle about its history. Its orbit together with the mean motion resonances of 4 of the 22 multi-planet systems provides further evidence for the role of planet–planet interactions in shaping planetary architectures.
Phys. Scr. T130. 01/2008; 82.
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J. T. Wright,
G. W. Marcy,
D. A. Fischer,
R. P. Butler,
S. S. Vogt,
C. G. Tinney,
H. R. A. Jones,
B.D. Carter,
J A Johnson,
C McCarthy,
K. Apps
[show abstract]
[hide abstract]
ABSTRACT: We present four new exoplanets: HIP 14810 b & c, HD 154345 b, and HD 187123 c. The two planets orbiting HIP 14810, from the N2K project, have masses of 3.9 and 0.76 M_jup. We have searched the radial velocity time series of 90 known exoplanet systems and found new residual trends due to additional, long period companions. Two stars known to host one exoplanet have sufficient curvature in the residuals to a one planet fit to constrain the minimum mass of the outer companion to be substellar: HD 68988 c with 8 M_jup < M sini < 20 M_jup and HD 187123 c with 3 M_jup < msini < 7 M_jup$, both with P > 8 y. We have also searched the velocity residuals of known exoplanet systems for prospective low-amplitude exoplanets and present some candidates. We discuss techniques for constraining the mass and period of exoplanets in such cases, and for quantifying the significance of weak RV signals. We also present two substellar companions with incomplete orbits and periods longer than 8 y: HD 24040 b and HD 154345 b with M sini < 20 M_jup and M sini < 10 M_jup, respectively.
12/2006;
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R. P. Butler, J. T. Wright,
G. W. Marcy,
D. A. Fischer,
S. S. Vogt,
C. G. Tinney,
H. R. A. Jones,
B.D. Carter,
J A Johnson,
C McCarthy,
A.J. Penny
[show abstract]
[hide abstract]
ABSTRACT: We present a catalog of nearby exoplanets, available at http://exoplanets.org and ApJ 646, 505 (published version available at the link above). It contains the 172 known low mass companions with orbits established through radial velocity and transit measurements around stars within 200 pc. We include 5 previously unpublished exoplanets orbiting the stars HD 11964, HD 66428, HD 99109, HD 107148, and HD 164922. We update orbits for 90 additional exoplanets including many whose orbits have not been revised since their announcement, and include radial velocity time series from the Lick, Keck, and Anglo-Australian Observatory planet searches. Both these new and previously published velocities are more precise here due to improvements in our data reduction pipeline, which we applied to archival spectra. We present a brief summary of the global properties of the known exoplanets, including their distributions of orbital semimajor axis, minimum mass, and orbital eccentricity.
08/2006;
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B. Sato,
D. A. Fischer,
G. W. Henry,
G. Laughlin,
R. P. Butler,
G. W. Marcy,
S. S. Vogt,
P. Bodenheimer,
S Ida,
E. Toyota, [......],
J. A. Valenti,
L. J. Boyd,
J A Johnson, J. T. Wright,
M. Ammons,
S. Robinson,
J. Strader,
C McCarthy,
K. L. Tah,
D. Minniti
[show abstract]
[hide abstract]
ABSTRACT: Doppler measurements from Subaru and Keck have revealed radial velocity variations in the V=8.15, G0IV star HD 149026 consistent with a Saturn-Mass planet in a 2.8766 day orbit. Photometric observations at Fairborn Observatory have detected three complete transit events with depths of 0.003 mag at the predicted times of conjunction. HD 149026 is now the second brightest star with a transiting extrasolar planet. The mass of the star, based on interpolation of stellar evolutionary models, is 1.3 +/- 0.1 solar masses; together with the Doppler amplitude, K=43.3 m s^-1, we derive a planet mass Msin(i)=0.36 Mjup, and orbital radius of 0.042 AU. HD 149026 is chromospherically inactive and metal-rich with spectroscopically derived [Fe/H]=+0.36, Teff=6147 K, log g=4.26 and vsin(i)=6.0 km s^-1. Based on Teff and the stellar luminosity of 2.72 Lsun, we derive a stellar radius of 1.45 Rsun. Modeling of the three photometric transits provides an orbital inclination of 85.3 +/- 1.0 degrees and (including the uncertainty in the stellar radius) a planet radius of 0.725 +/- 0.05 Rjup. Models for this planet mass and radius suggest the presence of a ~67 Mearth core composed of elements heavier than hydrogen and helium. This substantial planet core would be difficult to construct by gravitational instability. Comment: 25 pages, 5 figures, accepted by the Astrophysical Journal
The Astrophysical Journal 06/2005; · 6.02 Impact Factor
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[show abstract]
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ABSTRACT: We review the observed properties of exoplanets found by the Doppler technique which has revealed 152 exoplanets to date. We focus on our ongoing 18-year survey of 1330 FGKM type stars at Lick, Keck, and the Anglo-Australian Telescopes carried out with a uniform Doppler precision of 3 m/s. The 104 planets detected in our survey have masses as low as 15 M_Earth orbiting between 0.03 and 5.5 AU. The mass distribution rises toward the lowest detectable masses as dN/dM is proportional to M^-1.1. Nearly all giant planets orbiting within 2 AU of all FGK stars within 30 pc have now been discovered. The distribution of semi-major axes rises from 0.3 -- 3.0 AU (in bins of Delta log a), but remains unknown for larger orbits. Extrapolation suggests that 12% of the FGK stars harbor exoplanets within 20 AU. The median orbital eccentricity is =0.25 (excluding those tidally circularized), lower than previously measured . Planets orbiting beyond 3 AU continue to exhibit non-zero eccentricity, suggesting that the circular orbits of giant planets in our Solar System are unusual. The occurrence rate of ``hot Jupiters'' within 0.1 AU is 1.2$\pm$0.3 %. The probability of occurrence of planets varies as the square of the stellar metal abundance, $P \propto N^2_Fe, ranging from $<$3% for stars of subsolar metallicity to 25% for stars with [Fe/H] > +0.3. Nearly 14% of planet-bearing stars harbor multiple-planet systems, occasionally locked in resonances. Kepler and Corot should measure the occurrence of earth-sized planets. The Space Interferometry Mission (SIM) will detect planets with masses as low as 3 M_ Earth orbiting within 2 AU of nearby stars and will measure masses, orbits and multiplicity. These candidate rocky planets will motivate spectroscopic follow-up by the ``Terrestrial Planet Finder'' and Darwin.} Comment: Nishinomiya-Yukawa Symposium
04/2005;
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R. P. Butler, J. T. Wright,
G. W. Marcy,
D. A. Fischer,
S. Vogt,
C. G. Tinney,
H. R. A. Jones,
B.D. Carter,
J A Johnson,
C McCarthy,
A.J. Penny
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