(ORDO NEWS) — To date, 5,084 extrasolar planets have been confirmed in 3,811 planetary systems, with 8,912 more candidates awaiting confirmation.
These discoveries provided astronomers with a detailed sample of the types of planets that exist in our universe. , ranging from gas giants several times the size of Jupiter to smaller rocky bodies like Earth.
To date, the vast majority of them have been detected using indirect methods such as the transit method (transit photometry) and the radial velocity method (Doppler spectroscopy), while the rest have been detected using various other means.
In a recent study, an international team of astronomers used the National Science Foundation’s (NSF) Very Long Baseline Array (VLBA) to detect a Jupiter-like planet orbiting in a binary system (GJ 896AB) located about 20 light-years from Earth.
Using a technique known as astrometry, the team was able to detect this planet from the “wobble” it makes as it orbits the larger system. two stars. What’s more, this method allowed the team to create the first 3D architecture of a binary system and a planet that orbits one of its stars.
The research team was led by Salvador Curiel Ramírez, a researcher at the Institute of Astronomy at the National Autonomous University of Mexico (UNAM).
He was joined by colleagues from UNAM and researchers from the Radio Astronomy Institute. Max Planck (MPIFR) and the National Radio Astronomy Observatory (NRAO).
The paper describing their research, titled “3D Orbital Architecture of a Dwarf Binary and Its Planetary Companion,” was published Sept. 1 in The Astronomical Journal .
The system under study, GJ 896AB, consists of two red dwarfs orbiting each other. The larger of the two, the one orbiting the Jupiter-like exoplanet (GJ 896 Ab), has about 44% more mass than our Sun, while the smaller has about 17%.
They are separated by a distance close to that between Neptune and the Sun (~30 AU) and have an orbital period of 229 years. As Curiel explained in the NRAO press release, the 3D mapping they have done cannot be achieved with other exoplanet detection methods.
“Because most stars are in binary or multiple systems, being able to understand systems like this one will help us understand planetary formation in general,” he said.
In addition, M-type stars (red dwarfs) are the most common in the universe, making up about 75 percent of the stars in the Milky One alone.
These low-mass, dimmer stars can remain in their main sequence stage for up to 10 trillion years and are notable for supporting smaller rocky planets such as Proxima b and d and a seven-planet planet. TRAPPIST-1 system.
For their study, Curiel and colleagues combined VLBA data from 2006 to 2011 (and new data from 2020) with observations of the system from 1941 to 2017.
The resolution provided by ten VLBA telescopes in the US has produced extremely accurate measurements of p stars. changes over time.
They then performed an extensive analysis of the data, which revealed the orbital motions of the stars and their normal motions through space. This process, in which the positions and proper motions of stars are measured, is known as astrometry.
Their detailed assessment of the motion of the larger star showed a slight wobble as a result of the gravitational pull on the star, which revealed the existence of a planet orbiting it. Based on the level of gravitational influence, the team calculated that this planet is a gas giant with a mass about twice that of Jupiter.
They also determined that it orbits its parent star at a distance slightly less than that of Venus from the Sun, has an orbital period of 284 days, and is about 148 degrees from the orbits of the two stars.
“This means that the planet is moving around the main star in the opposite direction. relative to a secondary star around the primary star,” said co-author Gisela Ortiz-Leon, a researcher at UNAM and MPIA.
“Such a dynamic structure is observed for the first time. on a planet associated with a compact binary system, which, presumably, formed in the same protoplanetary disk.
The astrometric method will become a valuable tool for characterizing more planetary systems that will benefit from observatories like the planned Next Very Large Array (ngVLA).
This massive network will consist of t 244 18-meter (59 ft) dishes spaced 8,860 km (5,505 miles) apart, with an additional set of 19 6-meter (20 ft) dishes at the center of the telescope. /p>
The improved sensitivity will allow astronomers to detect smaller rocky planets that orbit closer to their stars – where “Earth-like” planets are most likely to be. Co-author Joel Sanchez-Bermudez of UNAM said:
“Additional detailed studies of this and similar systems could help us gain important insights into how planets form in binary systems.
There are alternative theories for the mechanism of formation, and additional data may indicate which is most likely.
In particular, current models indicate that such a large planet is unlikely to be the companion of such a small star, so these models may need to be adjusted.”
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