The First High-Precision Radial Velocity Search for Extra-Solar Planets

TL;DR

This paper details the pioneering high-precision radial velocity method for detecting exoplanets, highlighting early discoveries of Jovian-like planets around nearby stars using spectroscopic techniques.

Contribution

It presents the first high-precision radial velocity search for exoplanets, demonstrating the feasibility of detecting Jupiter-mass planets via Doppler shifts in stellar spectra.

Findings

Detected potential planetary companions to $\gamma$ Cep, $eta$ Gem, and $\epsilon$ Eri.

Confirmed initial planetary detections with extended data sets.

Identified the complexity of planetary systems around these stars.

Abstract

In the late 1970s and early 1980s, the introduction of solid-state, signal-generating detectors and absorption cells to impose wavelength fiducials directly on the starlight, the errors in stellar radial velocity (RV) measurements were reduced to the point where Doppler searches for planets became feasible. In 1980 we began to use a hydrogen fluoride gas cell with the CFHT coud\'{e} spectrograph and, for 12 years, monitored RVs of some 29 solar-type stars. Since extra-solar planets were expected to resemble Jupiter in both mass and orbit, we were awarded only three or four two-night observing runs each year. In 1988 we highlighted a potential planetary companion to $\gamma$ Cep (K1 IV), in 1993 one to $\beta$ Gem (K0 III), and another to $\epsilon$ Eri (K2 V) in 1992. The putative planets all resembled Jovian systems with periods and masses of 2.5 yr and 1.4 $M_{J}$, 1.6 yr and 2.6 $M_{J}$, and 6.9 yr and 0.9 $M_{J}$, respectively. All three were subsequently confirmed from more extensive data by the Texas group led by Cochran and Hatzes who derived the currently accepted orbital elements. None of the systems is simple and some still question $\epsilon$ Eri b.