October 24, 2012
Discovering Transiting Extrasolar Planets
Gaspar Bakos
Assistant Professor of Astrophysical Sciences
Princeton University
Discovering Transiting Extrasolar Planets
Gaspar Bakos
Assistant Professor of Astrophysical Sciences
Princeton University
Minutes of Sixth Meeting of the 71st Year
The President, Ruth Miller, opened the meeting at 10:15 AM. The invocation was led by Julia Cole. There were 78 members present.
Beryl McMillan read the Minutes of the Meeting of October 17th.
John Smith announced that ballots for new member applicants were being distributed and voting would take place at the next meeting. New members elected would be invited to attend the meeting on November 7th with their sponsors.
Glen Cullen introduced the speaker, Gaspar Bakos, who is an assistant professor in Astrophysical Sciences at Princeton University. Gaspar Bakos graduated from Eötvös Lóránd University (ELTE), Budapest, in 2004 with a PhD in Astrophysics. He worked a a Postdoctoral Fellow at the Center for Astrophysics at Harvard and at the Smithsonian Astrophysical Observatory before coming to Princeton in 2011.
Professor Bakos began by reviewing for us the structure of our solar system, which consists of 8 planets orbiting in the same direction around the sun. The inner planets, Mercury, Venus, Earth and Mars, are called the rocky planets because they consist mostly of rock and metals. The outer planets, Jupiter, Saturn, Uranus and Neptune are called the gas giants because they are much bigger and consist of 70% hydrogen and 20% helium.
The question arises: Are there similar planets around other stars? Since there are 200 billion stars in the Milky Way Galaxy alone, there could be billions of planets around those stars.
One of the methods for detecting exoplanets is the Transit Method. To illustrate this method Professor Bakos discussed the Transit of Venus which last occurred in June 2012 but only occurs in pairs every 120 years. By observing the dark disc of Venus transiting across the sun, one can calculate the distance from the earth to the sun and the distance from the earth to Venus as well as learning other important characteristics of Venus such as its mass, its size, its density, its orbital speed and something of its atmospheric content and surface temperature.
Other methods of detecting exoplanets include detecting star wobble using Doppler measurements, using Microlensing and direct observation. The Transit method has thus far detected 230 exoplanets out of a total discovery of about 1000 and is the chief method used in Professsor Bakos’s research.
Professor Bakos went on to describe the HATNET system which he was responsible for developing. Each instrument consists of 4 or six small telescopes on a geodesic mount which can scan the stars and record what is seen. The instruments are fully automated operating only during cloudless nighttime and shutting down during the day. Instruments are located in Arizona and Hawaii and a network is being set up in the southern hemisphere in Australia, Namibia and Chile. Data from these telescopes is routed to a computer cluster in the Lewis Library in Princeton for analysis. The system detects transits of planets in front of stars and then theses transits are checked on a larger telescope for confirmation. The HATNET telescopes cost tens of thousands of dollars versus $70 million for the Keck telescope in Hawaii or $600 million for the Kepler Satellite, which has been in operation for 31/2 years and whose function is to detect exoplanets. Thus because of the much lower cost of the HATNET equipment and the automated methods of observation exoplanets can be detected at a much lower cost.
In answer to a question Professor Bakos said that we have not yet found a planet hospitable for life. Most planets found are the size of Jupiter but Kepler has found planets in the habitable zone around stars. Habitable implies a temperature of 10 to 100 degrees Celsius, and the presence of water. But because a planet is in a habitable zone does not guarantee that it is inhabited. We do not know that life evolves in other worlds as it did on Earth.
Respectively submitted
Bruno J Walmsley
Beryl McMillan read the Minutes of the Meeting of October 17th.
John Smith announced that ballots for new member applicants were being distributed and voting would take place at the next meeting. New members elected would be invited to attend the meeting on November 7th with their sponsors.
Glen Cullen introduced the speaker, Gaspar Bakos, who is an assistant professor in Astrophysical Sciences at Princeton University. Gaspar Bakos graduated from Eötvös Lóránd University (ELTE), Budapest, in 2004 with a PhD in Astrophysics. He worked a a Postdoctoral Fellow at the Center for Astrophysics at Harvard and at the Smithsonian Astrophysical Observatory before coming to Princeton in 2011.
Professor Bakos began by reviewing for us the structure of our solar system, which consists of 8 planets orbiting in the same direction around the sun. The inner planets, Mercury, Venus, Earth and Mars, are called the rocky planets because they consist mostly of rock and metals. The outer planets, Jupiter, Saturn, Uranus and Neptune are called the gas giants because they are much bigger and consist of 70% hydrogen and 20% helium.
The question arises: Are there similar planets around other stars? Since there are 200 billion stars in the Milky Way Galaxy alone, there could be billions of planets around those stars.
One of the methods for detecting exoplanets is the Transit Method. To illustrate this method Professor Bakos discussed the Transit of Venus which last occurred in June 2012 but only occurs in pairs every 120 years. By observing the dark disc of Venus transiting across the sun, one can calculate the distance from the earth to the sun and the distance from the earth to Venus as well as learning other important characteristics of Venus such as its mass, its size, its density, its orbital speed and something of its atmospheric content and surface temperature.
Other methods of detecting exoplanets include detecting star wobble using Doppler measurements, using Microlensing and direct observation. The Transit method has thus far detected 230 exoplanets out of a total discovery of about 1000 and is the chief method used in Professsor Bakos’s research.
Professor Bakos went on to describe the HATNET system which he was responsible for developing. Each instrument consists of 4 or six small telescopes on a geodesic mount which can scan the stars and record what is seen. The instruments are fully automated operating only during cloudless nighttime and shutting down during the day. Instruments are located in Arizona and Hawaii and a network is being set up in the southern hemisphere in Australia, Namibia and Chile. Data from these telescopes is routed to a computer cluster in the Lewis Library in Princeton for analysis. The system detects transits of planets in front of stars and then theses transits are checked on a larger telescope for confirmation. The HATNET telescopes cost tens of thousands of dollars versus $70 million for the Keck telescope in Hawaii or $600 million for the Kepler Satellite, which has been in operation for 31/2 years and whose function is to detect exoplanets. Thus because of the much lower cost of the HATNET equipment and the automated methods of observation exoplanets can be detected at a much lower cost.
In answer to a question Professor Bakos said that we have not yet found a planet hospitable for life. Most planets found are the size of Jupiter but Kepler has found planets in the habitable zone around stars. Habitable implies a temperature of 10 to 100 degrees Celsius, and the presence of water. But because a planet is in a habitable zone does not guarantee that it is inhabited. We do not know that life evolves in other worlds as it did on Earth.
Respectively submitted
Bruno J Walmsley