Category Archives: Exoplanets
Using ground-based telescopes, an international team of astronomers has identified an atmosphere around the exoplanet GJ 1132b. Orbiting a red dwarf star a mere 39 light-years away this world is only about half again as large and massive as Earth, making it the smallest exoplanet to be discovered thus far with an atmosphere.
Unfortunately that likely means that although GJ 1132b is Earth-sized it’s not Earth-like. In order to even be detected in the manner that it was the atmosphere must be extremely thick, making this exoplanet more similar to Venus than Earth.
“An atmosphere that we would think of as Earth-like would be completely invisible to these observations, and to all other currently existing telescopes,” said Tom Louden, a physicist at the University of Warwick in Coventry, England (who wasn’t involved in the study.)
In what’s being called a “record-breaking exoplanet discovery” NASA announced today the detection of not one, not two, not three or four but seven exoplanets orbiting the ultra-cool dwarf star TRAPPIST-1, located just under 40 light-years away in the constellation Aquarius. (That’s astronomically very close, although still 235 trillion miles distant.) What’s more, these exoplanets aren’t bloated hot Jupiters or frigid Neptune-like worlds but rather dense, rocky planets similar in size to Earth…and at least three of them are well-positioned around their dim red star to permit liquid water to exist on their surfaces.
TRAPPIST-1 and its planets are like a miniature version of our inner Solar System; the star itself is only slightly larger than Jupiter with a mass about 8% of our Sun, and the planets B through H all have orbits smaller than the diameter of Mercury’s. Still, even an ultra-cool dwarf star has a habitable zone, and three of these planets lie within it. The others may very well also possess habitable regions on or inside them too.
“This discovery could be a significant piece in the puzzle of finding habitable environments, places that are conducive to life,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate in Washington, D.C. “Answering the question ‘are we alone’ is a top science priority and finding so many planets like these for the first time in the habitable zone is a remarkable step forward toward that goal.”
The seven-planet system was confirmed through (and named for) the ground-based TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) telescope as well as observations from NASA’s Spitzer Space Telescope.
“This is the most exciting result I have seen in the 14 years of Spitzer operations,” said Sean Carey, manager of NASA’s Spitzer Science Center at Caltech/IPAC in Pasadena. “Spitzer will follow up in the fall to further refine our understanding of these planets so that the James Webb Space Telescope can follow up. More observations of the system are sure to reveal more secrets.”
For the past couple of years the astronomy world has been abuzz with news of the strange and randomly-occurring dimming of the star KIC 8462852—aka Tabby’s Star—located 1,276 light-years away in the constellation Cygnus and recently observed by NASA’s Kepler spacecraft. Hypotheses about the cause range from conservative (a transiting cloud of comets) to quite speculative (an “alien megastructure” constructed around the star) but to date nothing seems to perfectly fit the observations. Now, researchers from Columbia University and UC Berkeley are proposing a new idea: the dimming of Tabby’s Star is being caused by debris left over from a planet that was consumed by the star thousands of years ago, the orbiting scraps from a case of stellar infanticide.
Read more in a Universe Today article by Matt Williams: Finally, An Explanation for the Alien Megastructure?
When searching nearby stars for exoplanets, astronomers typically either look for the dimming of the stars’ light as planets pass in front of them or try to see if the stars themselves exhibit a slight wobble due to the gravitational tug of orbiting worlds. But recently scientists using the Hubble Space Telescope have found a curious clue in the disk of gas and dust surrounding a star 192 light-years away: a long, darkened swath that orbits the star every 16 years and may indicate the presence of an orbiting planet.
“The fact that I saw the same motion over 10 billion miles from the star was pretty significant, and told me that I was seeing something that was imprinted on the outer disk rather than something that was happening directly in the disk itself,” said John Debes of the Space Telescope Science Institute (STScI) in Baltimore, Maryland, leader of the research team. “The best explanation is that the feature is a shadow moving across the surface of the disk.”
Read the full story from NASA at Hubble Captures ‘Shadow Play’ Caused by Possible Planet
It hasn’t even been found yet (they’re still working on that) but the recently-announced Planet Nine is already spurring discussion amongst the world’s astronomers. One of the recent topics surrounding this alleged new planet is (again, besides where it’s hiding) how it formed and how it got into the incredibly distant orbit it’s thought to be in. Estimated to be nearly as massive as Neptune, and possibly similarly gaseous as well, Planet Nine would be an anomaly among the small frozen balls of ice that typically haunt the outer Solar System. Recently, a team of scientists decided to investigate the possibility that Planet Nine did not originate in our Solar System at all but rather was captured from another star, back when the Sun’s stellar family was much closer together… and apparently much more trusting. (That’ll teach ’em.)