* Astronomy

Blobrana · L

RE: Kepler mission

Blobrana · L

NASA will host a news briefing at 11 a.m. PDT (2 p.m. EDT), Thursday, Sept. 15, to announce a new discovery by the Kepler mission.
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Blobrana · L

NASA mission looks for extra time to battle stellar noise.

The Kepler spacecraft has hit an unexpected obstacle as it patiently watches the heavens for exoplanets: too many rowdy young stars. The orbiting probe detects small dips in the brightness of a star that occur when a planet crosses its face. But an analysis of some 2,500 of the tens of thousands of Sun-like stars detected in Kepler's field of view has found that the stars themselves flicker more than predicted, with the largest number varying twice as much as the Sun. That makes it harder to detect Earth-sized bodies.
As a result, the analysis suggests that Kepler will need more than double its planned mission life of three-and-a-half years to achieve its main goal of determining how common Earth-like planets are in the Milky Way.
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Blobrana · L

Kepler's Astounding Haul of Multiple-Planet Systems

NASA's Kepler spacecraft is proving itself to be a prolific planet hunter. Within just the first four months of data, astronomers have found evidence for more than 1,200 planetary candidates. Of those, 408 reside in systems containing two or more planets, and most of those look very different than our solar system.
In particular, the Kepler systems with multiple planets are much flatter than our solar system. They have to be for Kepler to spot them. Kepler watches for a planet to cross in front of its star, blocking a tiny fraction of the star's light. By measuring how much the star dims during such a transit, astronomers can calculate the planet's size, and by observing the time between successive events they can derive the orbital period - how long it takes the planet to revolve around its star.
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Blobrana · L

Kepler Mission is a NASA program supported by a space observatory - the Kepler spacecraft - designed to discover Earth-like planets orbiting other stars. The spacecraft is named in honour of German astronomer Johannes Kepler. The spacecraft was launched on March 7, 2009, with a planned mission lifetime of at least 3.5 years.
Source

Blobrana · L

I'm not too sure about that; in the paper (previous post) it states that "Over 74% of the planetary candidates are smaller than Neptune".
But, yes, there will be some doubt as to the larger objects, which may be brown dwarfs, (the exact inclination of their orbits with respect to us, is a guess).
But i would agree with you, as for the very small objects there will be little doubt as to their planetlike nature (er, if they existence).
But i think most astronomers will be aware that while everyone calls these objects 'planets' or 'exoplanets' that they are technically just orbiting 'objects' (or 'planetary candidates') according the IAU definitions of 'Planet'.

heich1 · New

I have a question. The main reason that the Kepler team is afraid that a planet candidate is not declared a planet is that they are afraid that it is actually a star. I can see that would be possible if it were a large planet, as large as Jupiter or larger but would seem a lot less likely if it were a small Earth-size planet. I would be much obliged if you would explain their reasoning.

Blobrana · L

Title: Characteristics of planetary candidates observed by Kepler, II: Analysis of the first four months of data
Authors: William J. Borucki, David G. Koch, Gibor Basri, Natalie Batalha, Timothy M. Brown, Stephen T. Bryson, Douglas Caldwell, Jørgen Christensen-Dalsgaard, William D. Cochran, Edna DeVore, Edward W. Dunham, Thomas N. Gautier III, John C. Geary, Ronald Gilliland, Alan Gould, Steve B. Howell, Jon M. Jenkins, David W. Latham, Jack J. Lissauer, Geoffrey W. Marcy, Jason Rowe, Dimitar Sasselov, Alan Boss, David Charbonneau, David Ciardi, Laurance Doyle, Andrea K. Dupree, Eric B. Ford, Jonathan Fortney, Matthew J. Holman, Sara Seager, Jason H. Steffen, Jill Tarter, William F. Welsh, Christopher Allen, Lars A. Buchhave, Jessie L. Christiansen, Bruce D. Clarke, Jean-Michel Désert, Michael Endl, Daniel Fabrycky, Francois Fressin, Michael Haas, Elliott Horch, Andrew Howard, Howard Isaacson, Hans Kjeldsen,
Jeffery Kolodziejczak, Craig Kulesa, Jie Li, Pavel Machalek, Donald McCarthy, Phillip MacQueen, Søren Meibom, Thibaut Miquel, Andrej Prsa, Samuel N. Quinn, Elisa V. Quintana, Darin Ragozzine, William Sherry, Avi Shporer, Peter Tenenbaum, Guillermo Torres, Joseph D. Twicken, Jeffrey Van Cleve, Lucianne Walkowicz
et al. (19 additional authors not shown)

On 1 February 2011 the Kepler Mission released data for 156,453 stars observed from the beginning of the science observations on 2 May through 16 September 2009. There are 1235 planetary candidates with transit like signatures detected in this period. These are associated with 997 host stars. Distributions of the characteristics of the planetary candidates are separated into five class-sizes; 68 candidates of approximately Earth-size (radius < 1.25 Earth radii), 288 super-Earth size (1.25 Earth radii < radius < 2 Earth radii), 662 Neptune-size (2 Earth radii < radius < 6 Earth radii), 165 Jupiter-size (6 Earth radii < radius < 15 Earth radii), and 19 up to twice the size of Jupiter (15 Earth radii < radius < 22 Earth radii). In the temperature range appropriate for the habitable zone, 54 candidates are found with sizes ranging from Earth-size to larger than that of Jupiter. Five are less than twice the size of the Earth. Over 74% of the planetary candidates are smaller than Neptune. The observed number versus size distribution of planetary candidates increases to a peak at two to three times Earth-size and then declines inversely proportional to area of the candidate. Our current best estimates of the intrinsic frequencies of planetary candidates, after correcting for geometric and sensitivity biases, are 6% for Earth-size candidates, 7% for super-Earth size candidates, 17% for Neptune-size candidates, and 4% for Jupiter-size candidates. Multi-candidate, transiting systems are frequent; 17% of the host stars have multi-candidate systems, and 33.9% of all the candidates are part of multi-candidate systems.

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Blobrana · L

'Music of the stars' now louder

The Kepler space telescope measures the sizes and ages of stars five times better than any other means - when it "listens" to the sounds they make.
Bill Chaplin, speaking at the AAAS conference in Washington, said that Kepler was an exquisite tool for what is called "astroseismology".
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Blobrana · L

Early Results from the Kepler Planet Finding Mission

Florida Tech Astronomy & Astrophysics Public Lecture Series

"Early Results from the Kepler Planet Finding Mission"

Matt A. Wood, PhD

Florida Institute of Technology