Massive Exoplanet Evolved in Extreme 4-Star System

According to a team of astronomers headed by Dr Lewis Roberts from NASA’s Jet Propulsion Laboratory in Pasadena, an extrasolar gas giant called 30 Arietis Bb (30 Ari Bb) is the second known example of a planet residing in a system with four stars.



Artists conception of the 30 Ari star system. In the foreground is the primary star about which the massive exoplanet orbits. The primary's newly-found binary partner, a red dwarf, can be seen in the upper left and the secondary binary system can be seen to the upper right.

While 30 Ari Bb was known before, it was thought to reside in a system of three stars, not four.

The system, called 30 Ari, is located in the constellation Aries, approximately 136 light-years away.

“Star systems come in myriad forms. There can be single stars, binary stars, triple stars, even quintuple star systems. It’s amazing the way nature puts these things together,” Dr Roberts said.

The planet itself is enormous, with 9.88 times the mass of Jupiter. It orbits its primary star, 30 Ari B, every 335 days. This star has a relatively close partner star, which the planet does not orbit.

The pair, in turn, is locked in a long-distance orbit with another pair of stars about 1,670 AU away.

“It’s highly unlikely that this planet, or any moons that might circle it, could sustain life,” Dr Roberts and his colleagues said.

The first four-star planet, Ph1b, was discovered in the star system Kepler-64 (KIC 4862625) in 2013 by astronomers using data from NASA’s Kepler mission.

The latest discovery, reported in the Astronomical Journal (arXiv.org preprint), suggests that exoplanets in quadruple star systems might be less rare than once thought.

The similarity between Kepler-64 and 30 Ari is that both systems are quadruples consisting of two relatively close pairs that are widely separated.

In fact, recent studies have shown that this type of star systems is itself more common than previously believed.

“About 4% of Sun-like stars are in quadruple systems, which is up from previous estimates because observational techniques are steadily improving,” said team member Dr Andrei Tokovinin of the Cerro Tololo Inter-American Observatory in Chile.

The scientists also reported on a triple-star planetary system, HD 2638, which hosts a so-called hot-Jupiter.

This giant planet, named HD 2638b, orbits its primary star tightly, completing one lap every 3 days.

Source : sci-news.com

Planets orbiting Kepler 444 suggest there’s ancient life in the Milky Way

NASA’s exoplanet hunting Kepler space telescope has encountered a few problems as of late, but there’s still a mountain of data for astronomers to dig through from the last four years. Astronomers analyzing Kepler data recently uncovered something unusual — a solar system about 117 light years away in the direction of Lyra called Kepler-444 with at least five Earth-sized planets. That would be unusual enough, but this planetary system is also extraordinarily ancient at roughly 11.2 billion years.

Astronomers are intrigued by this discovery for several reasons. First, that’s a lot of small rocky planets. Kepler detects alien worlds by the transit method. It watches distant suns for slight dips in brightness that indicate a planet has passed between it and the telescope. These events can be used to calculate the characteristics of the planet, but it works best for larger worlds (super Earths and gas giants). Spotting five planets between the size of Mercury and Venus (basically a little smaller than Earth) is unusual.

 
Artistic Depiction of Kepler 444 with its Star
 The age of Kepler-444 is also something to note. At 11.2 billion years old, the planets orbiting this star were already older than Earth is now when our sun ignited 4.5 billion years ago. The universe itself is only 13.8 billion or so years old, making Kepler-444 one of the oldest stars in the Milky Way. It would have been from the first generation of stars that dotted the sky. Kepler-444 is still very sun-like because it’s 25% smaller and cooler. That means it burns through its nuclear fuel more slowly.

Finding small rocky planets that are billions of years older than Earth suggests that advanced life may have existed in the universe for a very long time. Life on Earth might be very new by comparison. Just think, planets similar to Earth were forming more than 7 billion years before Earth formed, and some of them could have supported life. If other first-generation stars like Kepler-444 have planets, uncountable civilizations could have come into being eons before the first single-cell life appeared on Earth.

The planets orbiting Kepler-444 themselves are not able to support life as we know it. All five planets are packed very close to the parent star with orbits closer than that of Mercury in our solar system. With solar years less than 10 Earth days, they definitely stood out in the Kepler data. The surfaces of these worlds have been baked by the intense heat, reducing any organic material to cinders.

Kepler-444 isn’t a bastion of alien life, but it improves our understanding of planetary formation and points us in a new direction. Astronomers are anxious to find other ancient stars with rocky planets in hopes they might prove more hospitable to life. What if there was still something alive on one of these ancient worlds? That might sound like science fiction right now, but maybe it won’t always be — there’s still a lot of data from Kepler, and future telescopes will improve our ability to spy distant exoplanets.

 Source: Geek.com