by Nola Taylor Redd
March 27, 2015
concept of the four-star system
shows a gas giant
orbiting its primary star (yellow),
while the newfound
red dwarf star (upper left) circles nearby.
In the distance lie
another pair of stars (upper right).
Credit: Karen Teramura, UH IfA
Planets with four suns in their sky may be more common than
previously thought, a new study suggests. Astronomers have spotted a
fourth star in a planetary system
called 30 Ari, bringing the number
of known planet-harboring quadruple-sun systems to two.
Numerous two- and three-star exoplanets
have been identified.
"Star systems come in myriad forms.
There can be single stars, binary stars, triple stars, even
quintuple star systems," study lead author Lewis Roberts, of
NASA's Jet Propulsion Laboratory in Pasadena, California, said
in a statement.
"Itís amazing the way nature puts
these things together."
30 Ari lies 136 light-years from the sun
in the constellation Aries.
Astronomers discovered a giant planet in
the system in 2009; the world is about 10 times more massive than
Jupiter and orbits its primary star every 335 days.
A second pair of stars lies
approximately 1,670 astronomical units (AU) away. (1 AU is the
distance between Earth and the sun - about 93 million miles, or 150
Lewis Roberts and his colleagues used the new "Robo-AO"
adaptive optics system at the
Palomar Observatory in California
to sweep the sky, examining hundreds of stars each evening for signs
This search identified a fourth star in
close proximity to 30 Ari's primary star.
A diagram of the
show the two pairs of
stars in orbit together,
while a planet
circles one of them.
The newfound star circles its companion once every 80 years, at a
distance of just 22 AU, but it does not appear to affect the
exoplanet's orbit despite such proximity.
This is a surprising result that will
require further observations to understand, researchers said.
To a hypothetical observer cruising through the giant planet's
atmosphere, the sky would appear to host one small sun and two
bright stars visible in daylight. With a large enough telescope, one
of the bright stars could be resolved into a binary pair.
The discovery marks just the second time a planet has been
identified in a four-star system. The first four-star planet, PH1b
or Kepler-64b, was spotted in 2012 by citizen scientists using
publicly available data from NASAís
Planets with multiple suns have become less of a novelty in recent
years, as astronomers have found a number of real worlds that
resemble Tatooine, Luke Skywalker's home planet in the Star Wars
Indeed, binary stars are more common than their singleton
And the new study suggests that more
planetary systems with two pairs of binary stars may be discovered
down the road.
"About four percent of solar-type
stars are in quadruple systems, which is up from previous
estimates because observational techniques are steadily
improving," co-author Andrei Tokovinin, of the
Cerro Tololo Inter-American Observatory
in Chile, said in the same statement.
Astronomers have confirmed
more than 800 planets beyond our own solar
system, and the discoveries keep rolling in.
In addition to finding a fourth star around 30 Ari, the team also
found a third star in a planetary system previously thought to
have only two suns.
This system, known as
HD 2638, was already known to host
a planet with half the mass of Jupiter rushing around its primary
star once every 3.4 days, while a second star lies about 44,000 AU,
or 0.7 light-years, away.
The newly discovered third star sits
just 28 AU from the primary star, and it appears to have influenced
the orbit of the gaseous planet, researchers said.
The research (A
Survey of the High Order Multiplicity of Nearby Solar-type Binary
Stars with Robo-AO) was published online this month in
the Astronomical Journal.