Radial Velocities as an Exoplanet Discovery Method

  • Jason T. WrightEmail author
Reference work entry


The precise radial velocity technique is a cornerstone of exoplanetary astronomy. Astronomers measure Doppler shifts in the star’s spectral features, which track the line-of-sight gravitational accelerations of a star caused by the planets orbiting it. The method has its roots in binary star astronomy, and exoplanet detection represents the low-companion-mass limit of that application. This limit requires control of several effects of much greater magnitude than the signal sought: the motion of the telescope must be subtracted, the instrument must be calibrated, and spurious Doppler shift “jitter” must be mitigated or corrected. Two primary forms of instrumental calibration are the stable spectrograph and absorption cell methods, the former being the path taken for the next generation of spectrographs. Spurious, apparent Doppler shifts due to non-center-of-mass motion (jitter) can be the result of stellar magnetic activity or photospheric motions and granulation. Several avoidance, mitigation, and correction strategies exist, including careful analysis of line shapes and radial velocity wavelength dependence.


  1. Bastien FA, Stassun KG, Basri G, Pepper J (2013) An observational correlation between stellar brightness variations and surface gravity. Nature 500:427–430., 1308.4728ADSCrossRefGoogle Scholar
  2. Bastien FA, Stassun KG, Pepper J et al (2014) Radial velocity variations of photometrically quiet, chromospherically inactive Kepler stars: a link between RV jitter and photometric flicker. AJ 147:29., 1310.7152ADSCrossRefGoogle Scholar
  3. Bean JL, Seifahrt A, Hartman H et al (2010) The proposed giant planet orbiting VB 10 does not exist. ApJ 711:L19–L23. Scholar
  4. Boisse I, Bouchy F, Hébrard G et al (2011) Disentangling between stellar activity and planetary signals. A&A 528:A4. Scholar
  5. Borucki WJ, Koch D, Basri G et al (2010) Kepler planet-detection mission: introduction and first results. Science 327:977–980 Scholar
  6. Butler RP, Marcy GW, Williams E et al (1996) Attaining Doppler precision of 3 M s-1. PASP 108:500ADSCrossRefGoogle Scholar
  7. Butler RP, Marcy GW, Williams E, Hauser H, Shirts P (1997) Three new “51 Pegasi–Type” planets. ApJ 474:L115ADSCrossRefGoogle Scholar
  8. Campbell B, Walker GAH (1979) Precision radial velocities with an absorption cell. PASP 91:540–545. Scholar
  9. Chubak C, Marcy G, Fischer DA et al (2012) Precise radial velocities of 2046 nearby FGKM stars and 131 standards. ArXiv e-prints 1207.6212ADSGoogle Scholar
  10. Dumusque X, Pepe F, Lovis C et al (2012) An earth-mass planet orbiting α centauri B. Nature 491:207–211. Scholar
  11. Fischer DA, Anglada-Escude G, Arriagada P, et al (2016) State of the field: extreme precision radial velocities. PASP 128:066001ADSCrossRefGoogle Scholar
  12. Gao P, Plavchan P, Gagné J et al (2016) Retrieval of precise radial velocities from near-infrared high-resolution spectra of low-mass stars. PASP 128(10):104,501., 1603.05997ADSCrossRefGoogle Scholar
  13. Hatzes AP (1996) Simulations of stellar radial velocity and spectral line bisector variations: I. nonradial pulsations. PASP 108:839. Scholar
  14. Hekker S, Reffert S, Quirrenbach A et al (2006) Precise radial velocities of giant stars. I. Stable stars. A&A 454:943–949., astro-ph/0604502ADSCrossRefGoogle Scholar
  15. Howard AW, Johnson JA, Marcy GW et al (2009) The NASA-UC Eta-Earth program. I. A super-earth orbiting HD 7924. ApJ 696:75–83., 0901.4394ADSCrossRefGoogle Scholar
  16. Johnson JA, Aller KM, Howard AW, Crepp JR (2010) Giant planet occurrence in the stellar mass-metallicity plane. PASP 122:905–915., 1005.3084ADSCrossRefGoogle Scholar
  17. Kasting JF, Whitmire DP, Reynolds RT (1993) Habitable zones around main sequence stars. Icarus 101:108–128. Scholar
  18. Kjeldsen H, Bedding TR, Butler RP et al (2005) Solar-like oscillations in α centauri B. ApJ 635:1281–1290. Scholar
  19. Latham DW, Stefanik RP, Mazeh T, Mayor M, Burki G (1989) The unseen companion of HD114762 – a probable brown dwarf. Nature 339:38–40. Scholar
  20. Lovis C, Dumusque X, Santos NC et al (2011, submitted) The HARPS search for southern extra-solar planets XXXI. Magnetic activity cycles in solar-type stars: statistics and impact on precise radial velocities. A&A arXiv:11075325 arXiv:1107.5325Google Scholar
  21. Mahadevan S, Ramsey L, Bender C et al (2012) The habitable-zone planet finder: a stabilized fiber-fed NIR spectrograph for the Hobby-Eberly Telescope. Proc SPIE 8446:84461S. Ground-based and airborne instrumentation for astronomy IV., 1209.1686.
  22. Marcy GW, Butler RP (1992) Precision radial velocities with an iodine absorption cell. PASP 104:270–277. Scholar
  23. Mayor M Queloz D (1995) A Jupiter-Mass companion to a solar-type star. Nature 378:355ADSCrossRefGoogle Scholar
  24. Pepe FA, Lovis C (2008) From HARPS to CODEX: exploring the limits of Doppler measurements. Phys Scr T130(1):014007. Scholar
  25. Pepe FA, Cristiani S, Rebolo Lopez R et al (2010) ESPRESSO: the Echelle spectrograph for rocky exoplanets and stable spectroscopic observations. In: Ground-based and airborne instrumentation for astronomy III. Proc SPIE 7735:77350F.
  26. Queloz D, Henry GW, Sivan JP et al (2001a) No planet for HD166435. A&A 379:279–287ADSCrossRefGoogle Scholar
  27. Queloz D, Mayor M, Udry S et al (2001b) From CORALIE to HARPS. The way towards 1 m s−1 precision Doppler measurements. Messenger 105:1–7Google Scholar
  28. Quirrenbach A, Amado PJ, Mandel H et al (2010) CARMENES: Calar Alto high-resolution search for M dwarfs with exo-earths with a near-infrared Echelle spectrograph. In: Ground-based and airborne instrumentation for astronomy III. Proc SPIE 7735:773513.
  29. Robertson P, Mahadevan S (2014) Disentangling planets and stellar activity for Gliese 667C. ApJ 793:L24., 1409.0021ADSCrossRefGoogle Scholar
  30. Robertson P, Mahadevan S, Endl M, Roy A (2014) Stellar activity masquerading as planets in the habitable zone of the M dwarf Gliese 581. Science 345:440–444., 1407.1049ADSCrossRefGoogle Scholar
  31. Wright JT (2005) Radial velocity jitter in stars from the California and Carnegie planet search at keck observatory. PASP 117:657–664. Scholar
  32. Wright JT, Eastman JD (2014) Barycentric corrections at 1 cm s−1 for precise Doppler velocities. PASP 126:838–852., 1409.4774ADSCrossRefGoogle Scholar
  33. Wright JT, Gaudi BS (2013) Exoplanet detection methods, p 489. Scholar
  34. Wright JT, Howard AW (2009) Efficient fitting of multiplanet Keplerian models to radial velocity and astrometry data. ApJS 182:205–215., 0904.3725ADSCrossRefGoogle Scholar
  35. Wright JT, Marcy GW, Butler RP et al (2008) The Jupiter twin HD 154345b. ApJ 683:L63–L66., arXiv:0802.1731ADSCrossRefGoogle Scholar
  36. Wright JT, Roy A, Mahadevan S et al (2013) MARVELS-1: a face-on double-lined binary star masquerading as a resonant planetary system and consideration of rare false positives in radial velocity planet searches. ApJ 770:119., 1305.0280ADSCrossRefGoogle Scholar

Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Astronomy and Astrophysics, Center for Exoplanets and Habitable WorldsThe Pennsylvania State UniversityUniversity ParkUSA

Personalised recommendations