not my area of expertise but sounds interesting:
http://news.discovery.com/space/alien-life-exoplanets/forget-tatooine-this-exoplanet-has-three-stars-160401.htm?fb_action_ids=10156771770385425&fb_action_types=og.likes said:Forget Tatooine, This Exoplanet Has THREE Suns
Apr 1, 2016 06:06 PM ET // by Ian O'Neill
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An artist's impression of a triple-star system, including a "hot-Jupiter" in a stable orbit around one of the stars.
UH Institute for Astronomy/Karen Teramura/Wei-Hao Wang, edit by Ian O'Neill
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As Luke Skywalker gazed longingly across the plains surrounding his aunt and uncle’s desert dwelling as the binary stars of Tatoo set over the horizon, imagine how much better that classic “Star Wars” scene would have looked if there were three suns!
Whether or not a stellar addition would have impacted this iconic space opera scene is debatable, but astronomers have just announced the discovery of just that: an exoplanet in a stable orbit around a star that occupies a triple star system.
ANALYSIS: ‘Baby Earth 2.0′ Found in Young Star’s Crib
But don’t go having fantasies of standing on that planet’s surface admiring some complex stellar dynamics at dusk, this particular world doesn’t have a solid surface. And it would be a really bad place to hang out if you didn’t want to be burned to a crisp.
Introducing KELT-4Ab: a gas giant world that orbits its parent star once every 3 days, but occupies a very rare multi-star system nearly 700 light-years from Earth.
The exoplanet was discovered by the wonderfully-named Kilodegree Extremely Little Telescope (KELT), a system of two small telescopes located in Arizona (KELT-North) and South Africa (KELT-South). Although the KELT-4 system has been known of for some time, it’s only recently that their triple-star nature has been realized. The system consists of a main bright star called KELT-4A and a binary pair of stars — called KELT-4B and KELT-4C, collectively known as KELT-4BC. KELT 4BC orbit one another every 30 years at a distance of only 10 AU (the approximate distance Saturn orbits the sun).
ANALYSIS: Massive Exoplanet Evolved in Extreme 4-Star System
This binary pair then orbits KELT-4A once every 4,000 years or so at a distance of approximately 330 AU (over 8 times the distance Pluto orbits the sun). It is around KELT-4A that a transiting exoplanet, designated KELT-4Ab, a world around 50 percent bigger than Jupiter, has been discovered.
As if this triple star system wasn’t bizarre enough, KELT-4Ab speeds around its host star in only 3 days, making this a “hot-Jupiter”. Its close proximity to KELT-4A has caused the exoplanet’s atmosphere to dramatically inflate. According to the planet’s discoverers in a study published in The Astrophysical Journal, its host star is the brightest host of any inflated hot-Jupiter discovered to date, so it could prove to be an invaluable astronomical target for further studies into the nature of these extreme worlds.
KELT-4Ab is only the fourth such exoplanet to be found in a stable orbit within a multi-star system, so this will be a great scientific opportunity to understand how exoplanets can form in multiple star systems when logic suggests they shouldn’t be gravitationally stable. But what would the sky of a planet in a 3-star system look like? Well, young Skywalker would be in for a shock.
ANALYSIS: Weirdly Wonky Binary Star System Discovered
If you were able to float in the upper layers of KELT-4Ab’s bloated atmosphere, you’d see the blindingly-bright main star, KELT-4A, take up a huge portion of the sky, 40 times wider than our sun appears to us on a clear day. The more distant KELT-4BC binary would appear much, much smaller as they are orbiting much further away, appearing no brighter than a full moon. They would, however, appear to be constantly hugging one another in their eternal orbital dance.
Source: The Astrophysical Journal via Physorg.com
http://www.astronomy.com/news/2016/04/andromedas-first-spinning-neutron-star-has-been-found#.VwLSP1z76vM.twitter said:
Andromeda’s first spinning neutron star has been found
While the precise nature of the system remains unclear, the data imply that it is unusual and exotic.
By ESA, Noordwijk, Netherlands | Published: Monday, April 04, 2016
RELATED TOPICS: MILKY WAY | NEUTRON STARS | ANDROMEDA GALAXY | PULSARS
Andromeda Galaxy
Andromeda's pulsing neutron star.
Andromeda: ESA/Herschel/PACS/SPIRE/J. Fritz, U. Gent/XMM-Newton/EPIC/W. Pietsch, MPE; data: P. Esposito et al. (2016)
Andromeda (M31) is a popular target among astronomers. Under clear dark skies, it is even visible to the naked eye. Its proximity and similarity in structure to our spiral galaxy, the Milky Way, make it an important natural laboratory for astronomers. It has been extensively studied for decades by telescopes covering the whole electromagnetic spectrum.
Despite the galaxy being extremely well studied, one particular class of object had never been detected — spinning neutron stars.
Neutron stars are the small and extraordinarily dense remains of a once-massive star that exploded as a powerful supernova at the end of its natural life. They often spin rapidly and can sweep regular pulses of radiation towards Earth, like a lighthouse beacon appearing to flash on and off as it rotates.
These “pulsars” can be found in stellar couples, with the neutron star cannibalizing its neighbor. This can lead to the neutron star spinning faster and to pulses of high-energy X-rays from hot gas being funneled down magnetic fields onto the neutron star.
Binary systems hosting a neutron star like this are quite common in our galaxy, but regular signals from such a pairing had never before been seen in Andromeda.
Now, astronomers systematically searching through the archives of data from XMM-Newton X-ray telescope have uncovered the signal of an unusual source fitting the bill of a fast-spinning neutron star.
It spins every 1.2 seconds, and appears to be feeding on a neighboring star that orbits it every 1.3 days.
“We were expecting to detect periodic signals among the brightest X-ray objects in Andromeda, in line with what we already found during the 1960s and 1970s in our galaxy,” said Gian Luca Israel from INAF-Osservatorio Astronomica di Roma, Italy. “But persistent bright X-ray pulsars like this are still somewhat peculiar, so it was not completely a sure thing we would find one in Andromeda.
“We looked through archival data of Andromeda spanning 2000–2013, but it wasn’t until 2015 that we were finally able to identify this object in the galaxy’s outer spiral in just two of the 35 measurements.”
While the precise nature of the system remains unclear, the data imply that it is unusual and exotic.
“It could be what we call a ‘peculiar low-mass X-ray binary pulsar’ — in which the companion star is less massive than our Sun — or alternatively an intermediate-mass binary system with a companion of about two solar masses,” said Paolo Esposito of INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan, Italy.
“We need to acquire more observations of the pulsar and its companion to help determine which scenario is more likely.”
“The well-known Andromeda galaxy has long been a source of exciting discoveries, and now an intriguing periodic signal has been detected by our flagship X-ray mission,” added Norbert Schartel from the European Space Agency (ESA).
“We’re in a better position now to uncover more objects like this in Andromeda, both with XMM-Newton and with future missions such as ESA’s next-generation high-energy observatory, ATHENA.”
