An iron and nickel-rich planetesimal is apparently all that survives of a planet following the death of its star, SDSS J122859.93+104032.9. We are talking about an object in an orbit around a white dwarf so tight that it completes a revolution every two hours. Significantly, spectroscopic methods were used to make the identification, the first time a solid body has been found around a white dwarf with spectroscopy. Variations in emitted light were used to identify the gases generated by the planetesimal, with data from the Gran Telescopio Canarias in La Palma. Lead author Christopher Manser (University of Warwick) notes the advantages of the method the team developed to study a white dwarf 400 light years away: "Our discovery is only the second solid planetesimal found in a tight orbit around a white dwarf, with the previous one found because debris passing in front of the star blocked some of its light -- that is the "transit method'' widely used to discover exoplanets around...

A method for enhanced exoplanet investigation takes center stage today as we look at the GRAVITY instrument, a near-infrared tool aided by adaptive optics that brings new precision to exoplanet imaging. In operation at the European Southern Observatory's Very Large Telescope Interferometer (VLTI) at Paranal Observatory in Chile, GRAVITY works with the combined light of multiple telescopes to produce what would otherwise take a single telescope with a mirror diameter of 100 meters to equal. The early demonstrator target is exoplanet HR 8799e. The method at work is interferometry, and here we are applying it to a ‘super Jupiter,’ more massive and much younger (at 30 million years) than any planet in our Solar System. The GRAVITY observations of this target mark the first time that optical interferometry has been used to study an exoplanet at this level of precision, producing a highly detailed spectrum. The planet is part of a 5-planet system some 130 light years away, all 5 of the...

Picking up on TESS (Transiting Exoplanet Survey Satellite), one of whose discoveries we examined yesterday, comes news of a document called the "TESS Habitable Zone Star Catalog." The work of Cornell astronomers in collaboration with colleagues at Lehigh and Vanderbilt, the paper has just been published in Astrophysical Journal Letters (citation below), where we find 1,822 stars where TESS may find rocky terrestrial planets. The listed 1,822 are nearby stars, bright, cool dwarfs, with temperatures roughly between 2,700 and 5,000 Kelvin, with a TESS magnitude brighter than 12 and reliable data from the Gaia Data Release 2 as to distance. Here TESS can detect 2 transits of planets that receive stellar irradiation similar to Earth's, during the 2-year prime mission. 408 of these stars would allow TESS to detect transiting planets down to Earth size during one transit. The catalog is fine-tuned to the TESS instrumentation and mission parameters, the stars selected because they offer...

It’s good to see TESS, the Transiting Exoplanet Survey Satellite, producing early results. We’re coming up on the one year anniversary of its launch last April 18, with the spacecraft’s four cameras doing month-long stares at 26 vertical strips of sky, beginning with the southern hemisphere. Two years of such scanning will produce coverage of 85 percent of the sky. The focus on bright, nearby stars is a shift from the Kepler strategy. While both missions have dealt with planetary transits across the face of their star as seen from the spacecraft, TESS is going to be producing plenty of data for follow-ups, planets close enough that we can consider studying their atmospheres with future missions beginning with the James Webb Space Telescope. Kepler’s long stare was of distant stars in a specific region, the idea being to gain a statistical understanding of the prevalence of planets. TESS gets us closer to home. Now we have TOI-197 (TOI stands for ‘TESS Object of Interest’), a planet...

Biosignature gases are those that can alert us to the possibility of life on a planet around another star. We're moving into the era of biosignature observation by studying the atmospheres of such planets through instruments like the James Webb Space Telescope, and the effort to catalog the combinations of atmospheric gases that point to life is intense and ongoing. One gas has turned out to be controversial. It's carbon monoxide, which in some quarters has been considered to be the opposite of a biosignature, a clear sign, if detected in sufficient abundance, that a planet is not inhabited. Edward Schwieterman (UC-Riverside) begs to disagree, and a team led by Schwieterman has produced its modeling of biosphere and atmosphere chemistry to focus on living planets that nonetheless support carbon monoxide at levels we should be able to detect. The work appears in the Astrophysical Journal. Interestingly, the paper harks back to our own planet's deep past. We don't expect to see high...

Kepler-62 is a reminder of how interesting K-class stars (like Alpha Centauri B) can be. Here we find two worlds that are conceivably in the habitable zone of their star, with Kepler 62f, imagined in the image below, orbiting the host star every 267 days. Kepler-62e, the bright object depicted to the right of the planet, may orbit within the inner edge of the habitable zone. Both planets are larger than Earth, Kepler 62f about 40 percent so, while Kepler-62e is 60 percent larger. Image: The artist's concept depicts Kepler-62f, a super-Earth-size planet in the habitable zone of a star smaller and cooler than the sun, located about 1,200 light-years from Earth in the constellation Lyra. Credit: NASA Ames/JPL-Caltech/Tim Pyle. We actually have five planets here, all known thanks to Kepler to transit their star. The two of habitable zone interest may or may not be solid planets -- their masses are not well constrained through either radial velocity or transit timing methods, so we are a...

A planet designated Kepler-1658b is, after a good deal of investigation, demonstrated to be a 'hot Jupiter,' orbiting a star that is 50 percent more massive and three times larger than the Sun. The sizzling world is close enough to its star that were you to look into its sky from near the planet, the star would be 60 times larger than the Sun as seen from Earth. And while none of this makes Kepler-1658b unique in our catalog, what does stand out is how we learned all this. For we are talking about the first planet candidate ever uncovered with the Kepler Space Telescope. Recall that for any transiting planet to be considered confirmed, we need a second kind of detection. The reason: Various astrophysical processes can mimic transit activity. Prudence dictates the backup, and in the case of Kepler-1658b, both the initial estimate of the star's size and the size of the planet were underestimated. The result was that the putative world became thought of as a false positive whose numbers...