Robert Paul Butler | |
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Born | April 1960 (age 63) |
Nationality | American |
Alma mater | San Francisco State University, University of Maryland, College Park |
Scientific career | |
Fields | Astronomy |
Institutions | San Francisco State University, Anglo-Australian Observatory, Carnegie Institution for Science |
External media | |
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Audio | |
The search for exoplanets, Adam Levy, Knowable Magazine, February 15, 2022 | |
Video | |
Paul Butler and the Search for Habitable Planets, Carnegie Science, January 9, 2013 |
Robert Paul Butler (born April 1960) is an astronomer and staff scientist at the Carnegie Institution for Science in Washington, D.C., who searches for extrasolar planets.
As of November 2020, [update] he and his team have discovered over half of the planets found orbiting nearby stars. He is noted for his pioneering work in Doppler spectroscopy, a method used to detect stars having orbiting planets by measuring the "wobble" induced by the gravitational forces between the star and its orbiting planet(s).
Butler was born in April 1960 in San Diego, California. Even as a boy, he was interested in astronomy. When he was 14, he built an 8-inch reflector telescope and began looking at planets and stars. He was fascinated by early astronomers and cosmologists like Galileo and Giordano Bruno, who dared to speculate about multiple worlds at a time when such ideas were considered heresy. [1] As a high school student in 1977, he learned techniques of orbit calculation when he attended the Summer Science Program at his school. [2]
Butler went on to receive a BA (physics, 1985), a BS (chemistry, 1986) and an MS (physics, 1989) from San Francisco State University, completing his Master's thesis with Geoffrey Marcy. During this time, he began work on the design of a very sensitive spectrograph, seeking to detect extrasolar planets by detecting variations in the radial velocity of their parent stars. [3] [2]
Butler received his Ph.D. in astronomy in 1993 from the University of Maryland College of Computer, Mathematical, and Natural Sciences in College Park, Maryland. [3]
While Butler was still working on his master's degree, he and Marcy developed a spectrographic apparatus capable of detecting the tiny gravitational effects of a planet on its host star. By viewing the starlight they measured through a glass absorption cell containing molecular iodine, they obtained a reference set of spectral lines with sufficient precision to identify the changing light waves caused by a stellar wobble. [4] [5] [6] After completing his Ph.D., Butler returned to San Francisco State University to work with Marcy. Butler was a research scientist there and a visiting research fellow at the University of California, Berkeley from 1993 to 1997. [7]
In 1995, Marcy and Butler used their Doppler velocity measurement equipment to confirm the discovery by Michel Mayor and Didier Queloz, of the first true exoplanet to be unequivocally identified orbiting a main sequence star, 51 Pegasi b. [5] [6] Its characteristics were so unexpected that researchers re-examined their assumptions and their data. [5]
In 1996 Marcy and Butler became the first Americans to discover a new planetary system, a planet orbiting 70 Virginis. The planet was detected using radial velocity measurements taken with the C. Donald Shane telescope at Lick Observatory. [8] [9] [4] [6] They went on to find 70 of the first 100 exoplanets to be discovered. [5]
In 1997 Butler became a staff astronomer at the Anglo-Australian Observatory in Sydney, Australia, leading the Anglo-Australian Planet Search. [7] After thirty years of research into exoplanets, few systems have been found that resemble the Solar System. [10] [11]
Since 1999, Butler has been a staff scientist at the Carnegie Institution for Science in Washington, D.C. [3] As of 2001, his expressed goal was "to survey all 2,000 Sun-like stars out to 150 light-years." [12]
Marcy and Butler have shared a number of prizes including the inaugural Bioastronomy Medal of the International Astronomical Union in 1997. [13] In 2001, Butler and Marcy were awarded the Henry Draper Medal from the National Academy of Sciences [14] "for their pioneering investigations of planets orbiting other stars via high-precision radial velocities." [15] The Carnegie Planet Search Team, consisting of Marcy, Butler, Steven Vogt and Debra Fischer received the Carl Sagan Award from the American Astronautical Society and the Planetary Society in 2002. [16] [13] Butler received the Beatrice Tinsley Prize of the American Astronomical Society with Marcy and Vogt in 2002. [13] [17] Marcy and Butler were named Discover Magazine's "Space Scientists of the Year" in 2003. [18]
In 2011, Butler was elected to the American Academy of Arts and Sciences for his work in developing the precision Doppler velocity technique, "the most precise method to date" for observing planets that orbit nearby stars, and for his many discoveries of such stars. Butler was credited with a "central role" in changing "the way we look at our place in the universe." [19]
Geoffrey William Marcy is an American astronomer. He was an early influence in the field of exoplanet detection, discovery, and characterization. Marcy was a professor of astronomy at the University of California, Berkeley, and an adjunct professor of physics and astronomy at San Francisco State University. Marcy and his research teams discovered many extrasolar planets, including 70 out of the first 100 known exoplanets and also the first planetary system around a Sun-like star, Upsilon Andromedae. Marcy was a co-investigator on the NASA Kepler mission. His collaborators have included R. Paul Butler, Debra Fischer and Steven S. Vogt, Jason Wright, Andrew Howard, Katie Peek, John Johnson, Erik Petigura, Lauren Weiss, Lea Hirsch and the Kepler Science Team. Following an investigation for sexual harassment in 2015, Marcy resigned his position at the University of California, Berkeley.
Debra Ann Fischer is a professor of astronomy at Yale University researching detection and characterization of exoplanets. She was part of the team to discover the first known multiple-planet system.
47 Ursae Majoris, formally named Chalawan, is a yellow dwarf star approximately 45.3 light-years from Earth in the constellation of Ursa Major. As of 2011, three extrasolar planets are believed to orbit the star.
Gliese 876 is a red dwarf star 15.2 light-years away from Earth in the constellation of Aquarius. It is one of the closest known stars to the Sun confirmed to possess a planetary system with more than two planets, after GJ 1061, YZ Ceti, Tau Ceti, and Wolf 1061; as of 2018, four extrasolar planets have been found to orbit the star. The planetary system is also notable for the orbital properties of its planets. It is the only known system of orbital companions to exhibit a near-triple conjunction in the rare phenomenon of Laplace resonance. It is also the first extrasolar system around a normal star with measured coplanarity. While planets b and c are located in the system's habitable zone, they are giant planets believed to be analogous to Jupiter.
55 Cancri b, occasionally designated 55 Cancri Ab, also named Galileo, is an exoplanet orbiting the Sun-like star 55 Cancri A every 14.65 days. It is the second planet in order of distance from its star, and is an example of a hot Jupiter, or possibly rather "warm Jupiter".
55 Cancri d, formally named Lipperhey, is an extrasolar planet in a long-period orbit around the Sun-like star 55 Cancri A. Located at a similar distance from its star as Jupiter is from the Sun, it is the fifth and outermost known planet in its planetary system. 55 Cancri d was discovered on June 13, 2002.
Gliese 876 b is an exoplanet orbiting the red dwarf Gliese 876. It completes one orbit in approximately 61 days. Discovered in June 1998, Gliese 876 b was the first planet to be discovered orbiting a red dwarf.
Upsilon Andromedae b, formally named Saffar, is an extrasolar planet approximately 44 light-years away from the Sun in the constellation of Andromeda. The planet orbits the solar analog star, Upsilon Andromedae A, approximately every five days. Discovered in June 1996 by Geoffrey Marcy and R. Paul Butler, it was one of the first hot Jupiters to be discovered. It is also one of the first non-resolved planets to be detected directly. Upsilon Andromedae b is the innermost-known planet in its planetary system.
Upsilon Andromedae c, formally named Samh, is an extrasolar planet orbiting the Sun-like star Upsilon Andromedae A every 241.3 days at an average distance of 0.83 AU. Its discovery in April 1999 by Geoffrey Marcy and R. Paul Butler made this the first multiple-planet system to be discovered around a main-sequence star, and the first multiple-planet system known in a multiple star system. Upsilon Andromedae c is the second-known planet in order of distance from its star.
These are lists of exoplanets. As of 19 December 2023, there are 5,566 confirmed exoplanets in 4,140 planetary systems, with 942 systems having more than one planet. Most of these were discovered by the Kepler space telescope. There are an additional 1,984 potential exoplanets from Kepler's first mission yet to be confirmed, as well as 977 from its "Second Light" mission and 4,589 from the Transiting Exoplanet Survey Satellite (TESS) mission.
47 Ursae Majoris b, formally named Taphao Thong, is a gas planet and an extrasolar planet approximately 46 light-years from Earth in the constellation of Ursa Major. The planet was discovered located in a long-period orbit around the star 47 Ursae Majoris in January 1996 and as of 2011 it is the innermost of three known planets in its planetary system. It has a mass at least 2.53 times that of Jupiter.
Doppler spectroscopy is an indirect method for finding extrasolar planets and brown dwarfs from radial-velocity measurements via observation of Doppler shifts in the spectrum of the planet's parent star. As of November 2022, about 19.5% of known extrasolar planets have been discovered using Doppler spectroscopy.
Pi Mensae b, also known as HD 39091 b, is an extrasolar planet approximately 60 light-years away in the constellation of Mensa. The planet was announced orbiting the yellow main-sequence star Pi Mensae in October 2001.
Epsilon Eridani b, also known as AEgir [sic], is an exoplanet approximately 10.5 light-years away orbiting the star Epsilon Eridani, in the constellation of Eridanus. The planet was discovered in 2000, and as of 2023 remains the only confirmed planet in its planetary system. It orbits at around 3.5 AU with a period of around 7.6 years, and has a mass around 0.6 times that of Jupiter. As of 2023, both the Extrasolar Planets Encyclopaedia and the NASA Exoplanet Archive list the planet as 'confirmed'.
HD 196050 b is an exoplanet with a 1378-day period and a minimum mass of 2.90 Jupiter masses. The average orbital distance is 2.54 astronomical units and the orbital eccentricity is 22.8%. The periastron (closest) distance is 1.96 AU and the apastron (farthest) distance is 3.12 AU. The average orbital velocity is 20.1 km/s and the semi-amplitude is 49.7 m/s. The longitude of periastron is 187° and the time of periastron is 2,450,843 JD.
WASP-17b is an exoplanet in the constellation Scorpius that is orbiting the star WASP-17. Its discovery was announced on 11 August 2009. It is the first planet discovered to have a retrograde orbit, meaning it orbits in a direction counter to the rotation of its host star. This discovery challenged traditional planetary formation theory. In terms of diameter, WASP-17b is one of the largest exoplanets discovered and at half Jupiter's mass, this made it the most puffy planet known in 2010. On 3 December 2013, scientists working with the Hubble Space Telescope reported detecting water in the exoplanet's atmosphere.
Steven Scott Vogt is an American astronomer of German descent whose main interest is the search for extrasolar planets.
The Lick–Carnegie Exoplanet Survey (LCES) is a search for exoplanets using the Keck I optical telescope of the W. M. Keck Observatory in Hawaii. The survey is sponsored by NASA and the National Science Foundation. The survey comprises a decade of observations. The survey is led by Steven Vogt, professor of astronomy and astrophysics at University of California at Santa Cruz, and R. Paul Butler of the Carnegie Institution.
Planet-hosting stars are stars which host planets, therefore forming planetary systems.