Thu. May 19th, 2022

First ALMA animation of two young stars in a circle

Artist’s impression of the young binary system XZ Tau. The two young stars in the system each have a protoplanetary disk around them that tilts relative to the other. The two young stars orbit in a plane different from that on each disk. Credit: ALMA (ESO / NAOJ / NRAO)

Researchers analyzed the accumulated data from the Atacama Large Millimeter / Submillimeter Array (ALMA) and depicted the motion of a young twin-star system XZ Tauri over three years. This first “ALMA Animation” of twin stars sheds new light on the origin of binary stars and the planets to be formed around them.


“This achievement was made possible by ALMA’s high resolution and rich archive data,” said Takanori Ichikawa, the first author of the research article and a former graduate student at Kagoshima University, Japan. “This research utilized three years of observational data. The results demonstrate the feasibility of a new research method using radio astronomical animations instead of conventional images. I hope this method will help clarify various astronomical phenomena in the future.”

The sun is a single star, but the universe is full of binary stars, which are two stars orbiting each other. In its youth, each young star in a binary system is surrounded by a protoplanetary disk composed of molecular gas and dust. This disk is known to be the site of planet formation. Many planets associated with binary stars have actually been discovered, but how the disks are formed in binary star systems and how planets are formed in these systems is still a mystery.

“To study the formation of planets in binary star systems, it is important to accurately determine the orbital motion of the two stars and the inclination of each protoplanetary disk,” explains Shigehisa Takakuwa, a professor at Kagoshima University.

First ALMA animation of two young stars in a circle

Orbital motion of the young binary XZ Tau system. The location of the XZ Tau A (bottom left) is fixed in the image and the relative motion of the XZ Tau B is displayed. The distributions of the radio waves from the protoplanetary disks are shown in grayscale (2015), red contours (2016) and blue contours (2017). The position of each star is shown as a plus sign. Credit: ALMA (ESO / NAOJ / NRAO), T. Ichikawa et al.

Researchers have proposed two mechanisms of formation for binary systems; one is a division of a single large gaseous disk, and the other is fragmentation of the larger molecular cloud due to violent turbulence. In the former case, astronomers assume that the orbit of the binary stars and the individual disks should be in the same plane. On the other hand, in the latter case, the orbital plane of the binary stars and the plane of the disks are expected to be different. This is a major problem that will affect the last lanes of plants in binary systems.

The research team dug into the ALMA data archive and collected the data for the young XZ Tau system taken in 2015, 2016 and 2017. They carefully analyzed the data and for the first time made an animation of the binary stars’ orbit, showing that XZ Tau B moved 3.4 astronomical units (3.4 times the radius of the Earth’s orbit) around XZ Tau A during these three years.

The team found out the three-dimensional structure of the circuit. Furthermore, by analyzing the Doppler effect and the distribution of the radio waves from the disk around each star in the XZ Tau system, they found that these disks are markedly incorrectly aligned with each other and not in the same plane as the binary circuit.

First ALMA animation of two young stars in a circle

Animated orbital motion of the young binary XZ Tau system. The location of the XZ Tau A (bottom left) is fixed in the image and the relative motion of the XZ Tau B is displayed. The distributions of the radio waves from the protoplanetary disks are shown in gray scale and contours. The position of each star is shown as a plus sign. Credit: ALMA (ESO / NAOJ / NRAO), T. Ichikawa et al.

Previous observations with ALMA had found examples of young binary stars with protoplanetary disks tilted relative to each other. However, this is the first time that the orbital motion of a binary system has been clarified, showing that the slope is different from those on the star disk. These results support the idea that the XZ Tau system was formed via molecular cloud fragmentation.

“This is a beautiful example of leveraging the rich ALMA archive,” says Takakuwa. “The archive paves the way for young researchers to start doing groundbreaking research right away.” That is true for this study. “I am very honored to be able to contribute to such interesting research as a bachelor’s student,” said Miyu Kido of Kagoshima University, co-author of the research article. “I hope to be able to use this experience in my own future research.”

These studies, “Misaligned Circumstellar Disks and Orbital Motion of the Young Binary XZ Tau,” are published in Astrophysical Journal on September 23, 2021.


The strange orbits on ‘Tatooine’ planetary disks


More information:
Takanori Ichikawa et al., Misaligned Circumstellar Disks and Orbital Motion of the Young Binary XZ Tau, The Astrophysical Journal (2021). DOI: 10.3847 / 1538-4357 / ac0dc3

Provided by the National Astronomical Observatory of Japan

Citation: First ALMA animation of circulating young young stars (2021, October 7) retrieved October 8, 2021 from https://phys.org/news/2021-10-alma-animation-circling-twin-young.html

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