Astronomers detect a circumbinary disk around the system Oph-IRS67AB

An international team of astronomers has discovered a circumbinary disk around the system Oph-IRS67AB and analyzed its chemistry as well as physical properties. The finding is detailed in a paper published February 26 on the arXiv pre-print repository.

Circumbinary disks are accretions of matter composed mainly of gas, dust, planetesimals and asteroids that orbit both the primary and secondary stars in binary systems. Given that astronomers have recently started detecting extrasolar worlds around binary systems, finding and studying such disks could improve the understanding of planetary formation scenarios.

Now, a group of researchers led by Elizabeth Artur de la Villarmois of the University of Copenhagen, Denmark, reports the finding of a circumbinary disk around the binary named Oph-IRS67AB. The system, located some 500 light years away in the Ophiuchus constellation, is composed of Oph-IRS67A and Oph-IRS67B, separated from each other by about 90 AU.

Using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, the team observed Oph-IRS67AB in mid-2015. The observations allowed the astronomers to detect the presence of a circumbinary disk around this system and to reveal its properties.

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Credit: De la Villarmois et al., 2018.

Continuum emission above 4σ in color scale and specific values of 7 and 15σ in white contours. The synthesised beam is represented by the black filled ellipse. The grey solid and dashed arrows cross at the geometric centre and they represent the direction of and perpendicular to the disk-like structure, respectively. The green and white stars show the positions of Oph-IRS67A and OphIRS67B, respectively. The red diamond denotes the location of the offset region.

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This artist's movie illustrates Kepler-47, the first transiting circumbinary system -- a system with more than one planet orbiting a pair of stars -- 4,900 light-years from Earth, in the constellation Cygnus.

 

Using data from NASA's Fermi Gamma-ray Space Telescope and other facilities, scientists have found the first gamma-ray binary in another galaxy and the most luminous one ever seen. The dual-star system, dubbed LMC P3, contains a massive star and a crushed stellar core that interact to produce a cyclic flood of gamma rays, the highest-energy form of light.

Gamma-ray binaries are rare -- only six are known in our own galaxy, and one remains undetected by Fermi. The systems are prized because their gamma-ray output changes significantly during each orbit and sometimes over longer time scales. This variation lets astronomers study many of the emission processes common to other gamma-ray sources in unique detail.

The systems contain either a neutron star or a black hole and radiate most of their energy in the form of gamma rays. Remarkably, LMC P3 is the most luminous such system known in gamma rays, X-rays, radio waves and visible light, and it's only the second one discovered with Fermi.