Radial-Velocity Standard Stars

Stefanik, R. P.; Latham, David W.; Torres, Guillermo

doi:10.1017/s0252921100048788

Cited by 38 publications

(30 citation statements)

References 13 publications

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“…We reduced the spectra following standard practice for this instrument 56 . We cross-correlated the spectra with an archival observation of Barnard's Star and found that the absolute radial velocity of G 229-20 A/B is 17.9 ± 0.1 km s −1 (on the IAU standard system 57 ). We also inspected the Hα line for G 229-20 A/B from the FIES spectrum.…”

Section: Spectroscopy Of G 229-20 A/bmentioning

confidence: 99%

A giant planet candidate transiting a white dwarf

Vanderburg

Rappaport

et al. 2020

Nature

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183

101

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Astronomers have discovered thousands of planets outside the solar system 1 , most of which orbit stars that will eventually evolve into red giants and then into white dwarfs. During the red giant phase, any close-orbiting planets will be engulfed by the star 2 , but more distant planets can survive this phase and remain in orbit around the white dwarf 3,4 . Some white dwarfs show evidence for rocky material floating in their atmospheres 5 , in warm debris disks [6][7][8][9] , or orbiting very closely [10][11][12] , which has been interpreted as the debris of rocky planets that were scattered inward and tidally disrupted 13 . Recently, the discovery of a gaseous debris disk with a composition similar to ice giant planets 14 demonstrated that massive planets might also find their way into tight orbits around white dwarfs, but it is unclear whether the planets can survive the journey. So far, the detection of intact planets in close orbits around white dwarfs has remained elusive. Here, we report the discovery of a giant planet candidate transiting the white dwarf WD 1856+534 (TIC 267574918) every 1.4 days. The planet candidate is roughly the same size as Jupiter and is no more than 14 times as massive (with 95% confidence). Other cases of white dwarfs with close brown dwarf or stellar companions are explained as the consequence of common-envelope evolution, wherein the original orbit is enveloped during the red-giant phase and shrinks due to friction. In this case, though, the low mass and relatively long orbital period of the planet candidate make common-envelope evolution less likely. Instead, the WD 1856+534 system seems to demonstrate that giant planets can be scattered into tight orbits without being tidally disrupted, and motivates searches for smaller transiting planets around white dwarfs. WD 1856+534 (hereafter, WD 1856 for brevity) is located 25 parsecs away in a visual triple star system. It has an effective temperature of 4710 ± 60 Kelvin and became a white dwarf 5.9 ± 0.5 billion years ago, based on theoretical models for how white dwarfs cool over time. The total system age, including the star's main sequence lifetime, must be older. Table 1 gives the other key parameters of the star. WD 1856 is one of thousands of white dwarfs that was targeted for observations with NASA's Transiting Exoplanet Survey Satellite (TESS ), in order to search for any periodic dimming events caused by planetary transits. A statistically significant transit-like event was detected by the TESS Science Processing Operations Center (SPOC) pipeline based

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Section: Spectroscopy Of G 229-20 A/bmentioning

confidence: 99%

A giant planet candidate transiting a white dwarf

Vanderburg

Rappaport

et al. 2020

Nature

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183

101

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“…The spectral coverage was 3820-4500 Å at a mean resolution of R ∼4500. Copper-Argon lamps were used between each exposure to calibrate the spectra to an RMS of 0.03 Å (2 km s −1 at 4500 Å), and the typical resolution was 1.0 Å FWHM at 3900 Å and 0.82 Å FWHM at 4400 Å. Spectra were Doppler corrected to the heliocentric frame and checked against the radial velocity standards HD131156 (G8V), HD146233(G2V), HD161096(K2III), HD161797(G5IV), and HD171391(G8III) from Stefanik et al (1999) before comparison to previous datasets.…”

Section: Observationsmentioning

confidence: 99%

Five More Massive Binaries in the Cygnus Ob2 Association

Kiminki¹,

Kobulnicky²,

Gilbert³

et al. 2009

The Astronomical Journal

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We present the orbital solutions for four OB spectroscopic binaries, MT145, GSC 03161-00815, 2MASS J20294666+4105083, and Schulte 73, and the partial orbital solution to the B spectroscopic binary, MT372, as part of an ongoing study to determine the distribution of orbital parameters for massive binaries in the Cygnus OB2 Association. MT145 is a new, single-lined, moderately eccentric (e = 0.291 ± 0.009) spectroscopic binary with period of 25.140 ± 0.008 days. GSC 03161-00815 is a slightly eccentric (e = 0.10 ± 0.01), eclipsing, interacting and double-lined spectroscopic binary with a period of 4.674 ± 0.004 days. 2MASS J20294666+4105083 is a moderately eccentric (e = 0.273 ± 0.002) double-lined spectroscopic binary with a period of 2.884 ± 0.001 days. Schulte 73 is a slightly eccentric (e = 0.169 ± 0.009), double-lined spectroscopic binary with a period of 17.28 ± 0.03 days and the first "twin" in our survey with a mass ratio of q = 0.99 ± 0.02. MT372 is a single-lined, eclipsing system with a period of 2.228 days and low eccentricity (e ∼ 0). Of the now 18 known OB binaries in Cyg OB2, 14 have periods and mass ratios. Emerging evidence also shows that the distribution of log(P ) is flat and consistent with "Öpik's Law".

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“…The modern era of radial velocity standards occurred with the work by the Geneva group led by Michel Mayor and Stephane Udry, the University of Victoria group led by Collin Scarfe and Robert McClure, and the group at the Harvard-Smithsonian Center for Astrophysics led by David Latham and Robert Stefanik (Mayor & Maurice 1985;Scarfe et al 1990;Latham et al 1991Latham et al , 2002. An excellent summary of the history of radial velocity standards through 1999 is provided by Stefanik et al (1999).…”

Section: Introductionmentioning

confidence: 99%

“…Three excellent radial velocity programs provided standards with high accuracy and integrity (Stefanik et al 1999;Udry et al 1999a,b), all of them constituting a modern velocity zero-point with accuracy better than 0.3 km s −1 . Additional excellent stellar radial velocity measurements were made by Nordström et al (2004); Famaey et al (2005) at accuracies of ∼0.3 km s −1 , and also by the Fick Observatory at Iowa State University, and at the Mt.…”

Section: Introductionmentioning

confidence: 99%

Precise Radial Velocities of 2046 Nearby FGKM Stars and 131 Standards

Chubak,

Marcy,

Fischer

et al. 2012

Preprint

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We present radial velocities with an accuracy of 0.1 km s −1 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 −1 . 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 −1 for G2V stars. This velocity zero-point agrees within 0.01 km s −1 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 −1 . 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 km s −1 for K dwarfs and ∼0.3 km s −1 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.

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Radial-Velocity Standard Stars

Cited by 38 publications

References 13 publications

A giant planet candidate transiting a white dwarf

A giant planet candidate transiting a white dwarf

Five More Massive Binaries in the Cygnus Ob2 Association

Precise Radial Velocities of 2046 Nearby FGKM Stars and 131 Standards

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