Activity-Related Radial Velocity Variation in Cool Stars

  title={Activity-Related Radial Velocity Variation in Cool Stars},
  author={Steven H. Saar and Robert A. Donahue},
  journal={The Astrophysical Journal},
  pages={319 - 327}
Planets have been detected orbiting several solar-type stars with the use of high-precision radial velocity (vr) measurements. While changes in vr can be measured with an accuracy of a few meters per second, there has been relatively little study of how other astrophysical processes, such as magnetic activity, may affect the observed velocities. In this paper, we use published data and simple models to explore the contributions to vr from two activity-related sources, starspots and convective… 

Magnetic Activity-related Radial Velocity Variations in Cool Stars: First Results from the Lick Extrasolar Planet Survey

The discovery of the radial velocity (vr) signatures of planets around several solar-like stars highlights the importance of exploring the sources of vr variations intrinsic to the stars themselves.

Correcting Radial Velocities for Long-Term Magnetic Activity Variations

It is argued that the main cause of these effects is modification of the mean line bisector shape brought on by long-term, magnetic activity-induced changes in the surface brightness and convective patterns.

Do stellar magnetic cycles influence the measurement of precise radial velocities

The ever increasing level of precision achieved by present and future radial-velocity instruments is opening the way to discovering very low-mass, long-period planets (e.g. solar-system analogs).

Unsigned Magnetic Flux as a Proxy for Radial-velocity Variations in Sun-like Stars

A major obstacle to detecting and characterizing long-period, low-mass exoplanets is the intrinsic radial-velocity (RV) variability of host stars. To better understand RV variability, we estimate

Long-term magnetic activity of a sample of M-dwarf stars from the HARPS program I. Comparison of activity indices

Context. The search for extra-solar planets similar to Earth is becoming a reality, but as the level of the measured radial-velocity reaches the sub-ms −1 , stellar intrinsic sources of noise capable

Starspot-Induced Radial Velocity Variability in LkCa 19

We describe a new radial velocity survey of T Tauri stars and present the first results. Our search is motivated by an interest in detecting massive young planets, as well as investigating the origin

Starspot-Induced Radial Velocity Jitter During a Stellar Cycle

Abstract Late-type stars exhibit cool regions on their surface, the stellar equivalent of sunspots. These dark starspots can also mimic the radial velocity variations caused by orbiting planets,

Radial Velocity Variations from Starspots

. In this contribution the radial velocity (RV) variations ex pected for starspots on solar-type stars are examined. The spot-induced RV amplitude is found to vary linearly with spot filling factor

Disentangling planetary orbits from stellar activity in radial-velocity surveys

Abstract The majority of extra-solar planets have been discovered (or confirmed after follow-up) through radial-velocity (RV) surveys. Using ground-based spectrographs such as High Accuracy Radial

From the Sun to solar-type stars: radial velocity, photometry, astrometry and logR′HK time series for late-F to early-K old stars

Abstract Solar simulations and observations showed that the detection of Earth twins around Sun-like stars is difficult in radial velocities with current methods techniques. The Sun has proved to be



Long, accurate time series measurements of radial velocities of solar-type stars

We have been measuring changes in the radial velocities (RV's) of solar-type stars to search for gravitational perturbations by planets. We transmit violet starlight through a Fabry-Perot etalon

Rotation, convection, and magnetic activity in lower main-sequence stars

Rotation periods are reported for 14 main-sequence stars, bringing the total number of such stars with well-determined rotation periods to 41. It is found that the mean level of their Ca n H and K

A Search for Jupiter-Mass Companions to Nearby Stars

Abstract We have carefully monitored the radial velocities of 21 bright, solar-type stars for 12 years, None has shown any reflex motion due to a substellar companion to an upper limit of between 1

Properties of Sun-like Stars with Planets: ρ1 Cancri, τ Bootis, and υ Andromedae

Planets have been reported orbiting the Sun-like stars ρ1 Cnc, τ Boo, and υ And based on low-amplitude radial velocity variations. We have derived information on the first two stars from analysis of


Convective envelope structures have been computed for the post-main-sequence evolutionary phases of 0.7-1.6 solar mass model stars having initial mass-fraction abundances of helium and heavier

A Planet Orbiting 47 Ursae Majoris

The G0 V star 47 UMa exhibits very low amplitude radial velocity variations having a period of 2.98 yr, a velocity amplitude of K = 45.5 m s-1, and small eccentricity. The residuals scatter by 11 m


The radial velocity and spectral variations are calculated for low-amplitude nonradial pulsations in slowly rotating stars (v sin i = 3 km s-1). Sectoral modes (l = -m) in the range l = 1-8 are


A powerful, new probe of chromospheric activity, cross-correlation, has been developed and applied to a variety of stars. In this particular application, an entire CCD spectrum of an active star is

The Emergence of Magnetic Flux Loops in Sunlike Stars

We explore the latitude of emergence of flux tubes at the surface of G stars as a function of the rotation rate, magnetic flux, and injection latitude at the bottom of the convective zone. Our

Properties of Sun-like Stars with Planets: 51 Pegasi, 47 Ursae Majoris, 70 Virginis, and HD 114762

Radial velocity variations have revealed planets orbiting 51 Peg, 47 UMa, and 70 Vir, and a low-mass companion orbiting HD 114762. We analyze parallel records of photometric measurements in Strömgren