‘Heartbeat Stars’ Unlocked in New Study

NASA press release

Heartbeat Star
The overlaid curve in depicts the inferred cyclic change in velocities in one such system, called KIC 9965691, looking something like the graph of an electrocardiogram. Credits: NASA/JPL-Caltech
Matters of the heart can be puzzling and mysterious — so too with unusual astronomical objects called heartbeat stars.

Heartbeat stars, discovered in large numbers by NASA’s Kepler space telescope, are binary stars (systems of two stars orbiting each other) that got their name because if you were to map out their brightness over time, the result would look like an electrocardiogram, a graph of the electrical activity of the heart. Scientists are interested in them because they are binary systems in elongated elliptical orbits. This makes them natural laboratories for studying the gravitational effects of stars on each other.

In a heartbeat star system, the distance between the two stars varies drastically as they orbit each other. Heartbeat stars can get as close as a few stellar radii to each other, and as far as 10 times that distance during the course of one orbit.

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Kepler Team Validates 41 New Exoplanets with Keck

W. M. Keck Observatory press release

The Kepler team today reports on four years of observations from the W. M. Keck Observatory targeting Kepler’s exoplanet systems, announcing results this week at the American Astronomical Society meeting in Washington. These observations, from Keck Observatory on the summit of Mauna Kea, confirm that numerous Kepler discoveries are indeed planets and yield mass measurements of these enigmatic worlds that vary between Earth and Neptune in size.

Kepler Planets
Chart of Kepler planet candidates as of January 2014., credit NASA Ames
More than three-quarters of the planet candidates discovered by NASA’s Kepler spacecraft have sizes ranging from that of Earth to that of Neptune, which is nearly four times as big as Earth. Such planets dominate the galactic census but are not represented in our own solar system. Astronomers don’t know how they form or if they are made of rock, water or gas.

Using one of the two world’s largest telescopes at Keck Observatory in Hawaii, scientists confirmed 41 of the exoplanets discovered by Kepler and determined the masses of 16. With the mass and diameter in-hand, scientists could immediately determine the density of the planets, characterizing them as rocky or gaseous, or mixtures of the two.

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First Earth-Sized, Rocky Exoplanet Found

W. M. Keck Observatory press release

A team of astronomers has found the first Earth-sized planet outside the solar system that has a rocky composition like that of Earth. This exoplanet, known as Kepler-78b, orbits its star very closely every 8.5 hours, making it much too hot to support life. The results are being published in the journal Nature.

Artist impression of the planet Kepler-78b and its host star. Credit: Karen Teramura (UH/IfA)
This Earth-sized planet was discovered using data from NASA’s Kepler Space Telescope, and confirmed and characterized with the W. M. Keck Observatory.

Every 8.5 hours the planet passes in front of its host star, blocking a small fraction of the starlight. These telltale dimmings were picked up by researchers analyzing the Kepler data.

The team led by Dr. Andrew Howard (Institute for Astronomy, University of Hawaii at Manoa) then measured the mass of the planet with the Keck Observatory on Mauna Kea, in Hawaii. Using the ten-meter Keck I telescope fitted with the HIRES instrument, the team employed the radial velocity method to measure how much an orbiting planet causes its star to wobble, to determine the planet’s mass. This is another excellent example of the synergy between the Kepler survey, which has identified more than 3,000 potential exoplanet candidates, and Keck Observatory, which plays a leading role in conducting precise Doppler measurements of the exoplanet candidates.

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Scientists Discover System with Three Planets in Habitable Zone

W. M. Keck Observatory press release

A team of scientists recently confirmed six, and possibly seven, planets orbiting a star system a mere 22 light-years from Earth. More importantly, three of those planets are super-Earths, lying in the Goldilocks Zone where liquid water could exist, making them possible candidates for the presence of life. This is the first system found with a fully-packed habitable zone. The findings will be published in the journal Astronomy & Astrophysics on June 26.

Previous studies of the triple star system called Gliese 667C showed the star hosts three planets with one of them in the habitable zone. Now, a team of astronomers has reexamined the system by re-mining existing European Southern Observatory’s HARPS data and combining it with data collected from the W. M. Keck Observatory and the Magellan Telescope to find evidence for up to seven planets around the star. These planets orbit the third faintest star of a triple star system. The two other suns would look like a pair of very bright stars visible in the daytime and at night they would provide as much illumination as the full Moon.
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Kepler Gets a Little Help From Its Friends

JPL press release

Kepler’s follow-up observers confirm new discoveries

More than 2,300 exoplanet candidate discoveries have made it the most prolific planet hunter in history. But even NASA’s Kepler mission needs a little help from its friends.

KIC 4862625
An artist’s illustration of an exoplanet system. Credit: Haven Giguere/Yale
Enter the Kepler follow-up observation program, a consortium of astronomers dedicated to getting in-depth with the mission’s findings and verifying them to an extremely high degree of confidence.

A single Kepler observation alone is often not enough to prove that the telescope has found an exoplanet, said Nick Gautier, the mission’s deputy project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., who coordinated and continues to help run Kepler’s robust follow-up program.

Kepler finds exoplanets by watching for worlds that move directly between the telescope and their host stars. As they do this, they block a tiny fraction of the star’s light, an event astronomers call a “transit.”

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