Dr. [Christopher Burke discusses the] latest results in measuring terrestrial planet occurrence rates using the planet candidates discovered by the Kepler pipeline.
For the first time an accurate model for the Kepler pipeline sensitivity to transiting planets is publicly available. Dr. Burke’s new analysis finds higher planet occurrence rates and a steeper increase in planet occurrence rates toward small planets than previously believed.
In addition, Dr. Burke will identify the leading sources of systematics that remain impacting Kepler planet occurrence rate determinations and approaches for minimizing their impact in future studies.
This work also sharpens our understanding on the dependence of planet occurrence rates on stellar effective temperature with potential implications for understanding the planet formation process.
The Kepler space observatory was thought to be out of the exoplanet finding business for good due to a failure in the guidance hardware. However, the system was returned to action using a clever technique with solar light pressure to maintain the telescope’s pointing stability. The K2 Mission, as this new phase of operation is called, has been underway for sometime now. This SETI Institute seminar gives an update
The NASA K2 mission makes use of the Kepler spacecraft to expand upon Kepler’s groundbreaking discoveries in the fields of exoplanets and astrophysics through new and exciting observations. K2 uses an innovative way of operating the spacecraft by carefully balancing the pressure of photons coming from the Sun. The K2 mission offers long-term, simultaneous optical observation of thousands of objects at high precision. Ecliptic fields are observed for approximately 75-days enabling a unique exoplanet survey which fills the gaps in duration and sensitivity between the Kepler and TESS missions, and offers exoplanet target identification for JWST transit spectroscopy. Astrophysics observations with K2 include studies of young open clusters such as the Pleiades and Hyades, galaxies, supernovae, and galactic archeology.
The Planetary Society‘s Planetary Radio program recently webcast two programs about the Breakthrough Initiative (see earlier post), which plans to spend $10M per year for the next ten years on a search for intelligent life beyond earth.
The Breakthrough Initiatives will pump $100 million into the Search for Extraterrestrial Intelligence in the next 10 years, vastly expanding humanity’s quest to learn if it has company in the universe. Among the leaders of this brave new project is Cosmos creator Ann Druyan. Join us for a special, extended conversation with Ann.
We follow last week’s conversation with Ann Druyan about the $100 million funding of the Search for Extraterrestrial Intelligence by visiting with two of the scientists who will do the work: Dan Werthimer of UC Berkeley and Karen O’Neil of the Green Bank Telescope.
According to Ruslan Belikov and Eduardo Bendek, two research scientists at NASA’s Ames Research Center in California, a 45-kilogram space telescope with a 30-to-45-centimeter mirror would be sufficient to deliver images of rocky planets in the habitable zones of either Alpha Centauri A or B. That’s smaller than some of the telescopes you can buy on Amazon.com, though you can’t purchase a planet-imaging space observatory off-the-shelf quite yet. Belikov, Bendek, and their collaborators call the concept ACESat – the Alpha Centauri Exoplanet Satellite – and have submitted it to NASA in response to the agency’s October 2014 call for proposals for Small Explorer missions, which have budgets capped at $175 million. If selected, the mission would be ready to launch no later than the end of 2020.
The brevity of the bursts is particularly unusual because it means their source has to be extremely small, hundreds of kilometers across at most. And because they exhibit such a high pulse dispersion — a measure of the distance between the arrival of higher frequency waves within the signal compared to lower frequency waves — scientists believe they come from very far away, possibly another galaxy entirely.
All 10 of the bursts detected so far have dispersion measures that are multiples of a single number: 187.5. That’s the mathematical regularity that is hard to shake off. The breakdown of the pattern implies five sources for the bursts all at regularly spaced distances from Earth, billions of light-years away. Scientists have calculated this to be a five in 10,000 probability of a coincidence. In other words, not likely.
“If the pattern is real, it is very, very hard to explain,” said John Learned, a scientist at the University of Hawaii in Manoa who analyzed the FRBs.
Using NASA’s Spitzer Space Telescope, astronomers have confirmed the discovery of the nearest rocky planet outside our solar system, larger than Earth and a potential gold mine of science data.
Dubbed HD 219134b, this exoplanet, which orbits too close to its star to sustain life, is a mere 21 light-years away. While the planet itself can’t be seen directly, even by telescopes, the star it orbits is visible to the naked eye in dark skies in the Cassiopeia constellation, near the North Star.
This artist’s concept shows the silhouette of a rocky planet, dubbed HD 219134b. At 21 light-years away, the planet is the closest outside of our solar system that can be seen crossing, or transiting, its star. Credits: NASA/JPL-CaltechHD 219134b is also the closest exoplanet to Earth to be detected transiting, or crossing in front of, its star and, therefore, perfect for extensive research.
“Transiting exoplanets are worth their weight in gold because they can be extensively characterized,” said Michael Werner, the project scientist for the Spitzer mission at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. “This exoplanet will be one of the most studied for decades to come.”
This sky map shows the location of the star HD 219134 (circle), host to the nearest confirmed rocky planet found to date outside of our solar system. The star lies just off the “W” shape of the constellation Cassiopeia and can be seen with the naked eye in dark skies. It actually has multiple planets, none of which are habitable. Credits: NASA/JPL-Caltech/DSSThe planet, initially discovered using HARPS-North instrument on the Italian 3.6-meter Galileo National Telescope in the Canary Islands, is the subject of a study accepted for publication in the journal Astronomy & Astrophysics.
Study lead author Ati Motalebi of the Geneva Observatory in Switzerland said she believes the planet is the ideal target for NASA’s James Webb Space Telescope in 2018.
“Webb and future large, ground-based observatories are sure to point at it and examine it in detail,” Motalebi said.
Only a small fraction of exoplanets can be detected transiting their stars due to their relative orientation to Earth. When the orientation is just right, the planet’s orbit places it between its star and Earth, dimming the detectable light of its star. It’s this dimming of the star that is actually captured by observatories such as Spitzer, and can reveal not only the size of the planet but also clues about its composition.
“Most of the known planets are hundreds of light-years away. This one is practically a next-door neighbor,” said astronomer and study co-author Lars A. Buchhave of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. For reference, the closest known planet is GJ674b at 14.8 light-years away; its composition is unknown.
This artist’s rendition shows one possible appearance for the planet HD 219134b, the nearest confirmed rocky exoplanet found to date outside our solar system. The planet is 1.6 times the size of Earth, and whips around its star in just three days. Scientists predict that the scorching-hot planet — known to be rocky through measurements of its mass and size — would have a rocky, partially molten surface with geological activity, including possibly volcanoes. Credits: NASA/JPL-CaltechHD 219134b was first sighted by the HARPS-North instrument and a method called the radial velocity technique, in which a planet’s mass and orbit can be measured by the tug it exerts on its host star. The planet was determined to have a mass 4.5 times that of Earth, and a speedy three-day orbit around its star.
Spitzer followed up on the finding, discovering the planet transits its star. Infrared measurements from Spitzer revealed the planet’s size, about 1.6 times that of Earth. Combining the size and mass gives it a density of 3.5 ounces per cubic inch (six grams per cubic centimeter) — confirming HD 219134b is a rocky planet.
Now that astronomers know HD 219134b transits its star, scientists will be scrambling to observe it from the ground and space. The goal is to tease chemical information out of the dimming starlight as the planet passes before it. If the planet has an atmosphere, chemicals in it can imprint patterns in the observed starlight.
Rocky planets such as this one, with bigger-than-Earth proportions, belong to a growing class of planets termed super-Earths.
“Thanks to NASA’s Kepler mission, we know super-Earths are ubiquitous in our galaxy, but we still know very little about them,” said co-author Michael Gillon of the University of Liege in Belgium, lead scientist for the Spitzer detection of the transit. “Now we have a local specimen to study in greater detail. It can be considered a kind of Rosetta Stone for the study of super-Earths.”
Further observations with HARPS-North also revealed three more planets in the same star system, farther than HD 219134b. Two are relatively small and not too far from the star. Small, tightly packed multi-planet systems are completely different from our own solar system, but, like super-Earths, are being found in increasing numbers.
JPL manages the Spitzer mission for NASA’s Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology (Caltech) in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company in Littleton, Colorado. Data are archived at the Infrared Science Archive, housed at Caltech’s Infrared Processing and Analysis Center.
For more information about NASA’s Spitzer Space Telescope, visit: www.nasa.gov/spitzer
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