The start of the birth of planets in a binary star system observed

The Institute of Astrophysics of Andalusia (IAA-CSIC) leads the study of the binary star SVS 13, still in its embryonic phase. Astronomers have observed primordial material that may be giving birth to three planetary systems around a binary star.

Astronomers have observed primordial material that may be giving birth to three planetary systems around a binary star in unprecedented detail. 

Bringing together three decades of study, an international group of scientists have observed a pair of stars orbiting each other, to reveal that these stars are surrounded by disks of gas and dust. Research published today in The Astrophysical Journal, shows the material within the newly discovered disks could be the beginnings of new planet systems which in the future orbit the binary stars.

The Institute of Astrophysics of Andalusia (IAA-CSIC) leads a study based on data from Calar Alto Observatory (CAHA), showing the variability of the planetary nebula IC4997.

An international team of astronomers used two of the most powerful radio telescopes in the world to create more than three hundred images deal new details about the birthplaces of planets and the earliest stages of star formation.

Astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) have found new evidence suggesting that a jet of fast-moving material ejected from one young star may have triggered the formation of another, younger protostar.

The ALMA Observatory in Chile has detected dust around the closest star to the Solar System, Proxima Centauri. These new observations reveal the glow coming from cold dust in a region between one to four times as far from Proxima Centauri as the Earth is from the Sun. The data also hint at the presence of an even cooler outer dust belt and may indicate the presence of an elaborate planetary system. These structures are similar to the much larger belts in the Solar System and are also expected to be made from particles of rock and ice that failed to form planets.

Osorio et al. (2016) present the discovery of a miniature protoplanetary disk around the star XZ Tau B. This discovery was made from observations using the Atacama Large Millimeter/Submillimeter Array (ALMA). XZ Tau B is a young red dwarf star estimated to be only ~4.6 million years old. It is located ~450 light years away, and it has ~1.2 times the radius and ~0.37 times the mass of the Sun. The large radius of the star indicates that it is still in the process of contracting to its final radius. The estimated effective temperature of XZ Tau B is 3550 K.

In late 2014, a team of astronomers led by Mayra Osorio of the Institute of Astrophysics of Andalusia in Granada, Spain, has used a set of 42 antennas at the Atacama Large Millimeter Array (ALMA) in Chile, to conduct observations of XZ Tau B. The scientists noticed that this star is a source of a dust emission, forming what appears to be a transitional protoplanetary disk.

In the course of the last few decades, the discovery of thousands of planets around other stars has unveiled a wide variety of planetary systems whose architecture defies our understanding of planet formation. The search for disks of gas and dust around young stars, from which planetary systems stem, is fundamental to explain newly observed worlds, and a recent finding confirms that miniature systems can exist. 
The discovery, made by an international team led by researchers from the Institute of Astrophysics of Andalusia  (IAA-CSIC), was made in the vicinity of XZ Tau B star which, with less than five million years of existence (the Sun, for comparison, is five billion years old), is so young that it has not yet completed its contraction process.

Astronomers using the Karl G. Jansky Very Large Array (VLA) have mapped the structure of a disk of dust surrounding a young star, revealing a pair of gaps in the disk where new planets are likely forming. “We’re looking at the very early stages of planetary formation in this system,” said Mayra Osorio, of the Astrophysical Institute of Andalucía (IAA-CSIC) in Spain. The international team of scientists studied a young star designated HD 169142, nearly 500 light-years from Earth. They used the VLA to observe the star at radio frequencies of 42-48 GHz, or wavelengths of about 7 mm, a technique well-suited to detecting grains of dust surrounding the star. What they found was that the star is surrounded by a dusty disk with a radius about 240 times the Earth-Sun distance. The disk has two gaps — an inner gap ranging from just less than the Sun-Venus distance out to just under the Sun-Neptune distance, and another ranging from roughly the Sun-Pluto distance out to 67 times the Earth-Sun distance.

Observations using the VLA radio telescope array in New Mexico show the innermost portion of a planetary birthplace around the young star HL Tauri in unprecedented detail. Clearly visible is a lump of dust with 3 to 8 times the mass of the Earth, which represents the ideal conditions for the formation of a planet: a planetary nursery with sufficient building material for a planet somewhere between the mass of our own Earth and that of Neptune. The presence of a lump points towards a solution for a fundamental problem of planet formation: how planets can form on the limited time scale available for such processes.

HD169142 is a young star with twice the mass of the Sun and whose disk extends up to two hundred and fifty astronomical units (an astronomical unit, or AU, is a unit equivalent to the distance between the Sun and the Earth: one hundred and fifty million kilometers). The system is in an optimal orientation for the study of planet formation because the disk is seen face-on.

The first article explores the disk of HD169142 with the Very Large Array radio telescope, which can detect centimeter-sized dust grains. The results, combined with which trace the presence of microscopic dust, reveal two gaps in the disk, one in the inner region (between 0.7 and 20 AU) and another, farther out and less developed, between 30 and 70 AU.

Most stars form binary systems, in which two stars revolve around a common center. However, models of planet formation, which suggest that planets are born by the slow aggregation of ice and dust particles in protoplanetary disks around forming stars, usually consider only single stars, such as the Sun. Thus, it is still unknown how planets are born around double stars, in which the gravitational interaction between the two plays an essential role. Using the Very Large Array (radio astronomical observatory in New Mexico) and the Atacama Large Millimeter/Submillimeter Array (the largest radio telescope in the world), a scientific group led by CSIC researchers has studied the binary star SVS 13, still in its embryonic phase, and has provided the best description available so far of a binary system in formation.