VLBA revolves around small, quiet stars


The illustration shows how the motion of the stars around the center of mass between the planet and it causes it to “waver” in its motion through space. The ability of VLBA to detect this negative effect led to the presence of the planet. Sincerely: Bill Saxon, NRAO / AUI / NSF

Using the superspar radio “vision” of the National Science Foundation’s continent-wide Very Long Baseline Array (VLBA), astronomers have discovered a planet the size of Saturn, a small, cool star on Earth 35 light-years away. Is revolving This is the first discovery of an extrasolar planet with a radio telescope, using a technique that requires extremely accurate measurement of the position of a star in the sky, and that technique requires only the discovery of another planet and For radio telescopes.


The technique has been known for a long time, but has proved difficult to use. This involves tracking the actual motion of the star in space, then detecting a molecular “wobble” at that speed due to the gravitational effect of the planet. The star and the planet revolve around a space that represents the center of mass for both. The planet appears indirectly if that space, called biarsent, is sufficient to cause a double detachable by the telescope from the center of the star.

This technique, called astrometric technique, is expected to be good for detecting planets such as Jupiter, especially in orbits far from the star. The reason for this is that when a giant planet orbits a star, the wobble that originates in the star increases with a greater separation between the planet and the star, and at a given distance from the star, the larger the planet Is, the larger the wobble is produced.

Starting in June of 2018 and continuing for a year and a half, astronomers tracked down a star called TVLM 513-46546, a cool dwarf with less than a tenth the mass of our Sun. In addition, they used data from nine previous VLBA observations of the star between March 2010 and August 2011.


Comprehensive analysis of those time period data revealed a telltale wobble in the motion of the star, indicating the presence of a comparable planet in the mass of Saturn, which orbits the star once every 221 days. This planet is closer to Mercury than the Sun.

Small, cool stars like TVLM 513-46546 are among the most numerous types in our Milky Way Galaxy, and many of them have small planets, comparable to Earth and Mars.

“Huge planets such as Jupiter and Saturn are expected to be rare around such small stars, and astrological techniques are best for finding planets like Jupiter in wide orbits, so we were surprised to see a low mass, Saturn-like Planets in a relatively compact orbit. We found a more massive planet, similar to Jupiter, in a wider orbit, said Salvador Curiel of the National Autonomous University of Mexico. He said, “This orbital orbit of the larger planetary companion of this sub-Jupiter. Orbiting around was a big challenge. ”

More than 4,200 planets have been discovered orbiting stars other than the Sun, but the planet around TVLM 513-46546 is the second to be found using astrometric technology only. Another, very successful method, called the radial velocity technique, also relies on the planet’s gravitational effect on the star. That technique detects the slight acceleration of the star, either toward or away from Earth, caused by the motion around the star.


Animation of stars and planets as they move through space, orbiting each other. Sincerely: Bill Saxon, NRAO / AUI / NSF

“Our method follows the method of radial velocity, which is more sensitive to planets orbiting in close orbits, while we have large-scale planets orbiting away from the star,” at the Max Planck Institute for Radio Astronomy Gisela Ortiz-Leon said Germany. “In fact, in these other techniques only a few planets have been found such as planetary mass, orbital shape and host star mass, such as the planet we found. We believe that VLBAs and astronomy techniques in general, may reveal many. Is. More equal planets. ”

A third technique, also known as the transit method, is very successful when the planet passes in front of the Earth, detecting a slight wetness of the starlight.

The astrometric method has been successful for detecting adjacent binary star systems, and was recognized as a possible means of exploring extrasolar planets in the early 19th century. Over the years, many such discoveries were announced, then failed to survive further investigation. The difficulty has been that the stellar doublet generated by a planet is so small when viewed from Earth that it requires exceptional accuracy in position measurement.

Amy Modiszewski of the National Radio Astronomy Observatory said, “The VLBA, with antennas separated with a range of 5,000 miles, provides us with very resolving power and extremely high precision for this discovery.” “In addition, improvements made to the sensitivity of VLBAs have given us data quality that has now made it possible to do this work,” she said.

Curiel, Ortiz-Leon, Modisujevski and Rosa Torres of the University of Guadalajara in Mexico reported their findings Astronomical Journal.


The newly discovered exoplanet detron of the former king of the Kepler-88 planetary system


more information:
Salvador Curiel et al. An astrometric planetary companion candidate for the M9 dwarf TVLM 513–46546, The Astronomical Journal (2020). DOI: 10.3847 / 1538-3881 / ab9e6e

Provided by the National Radio Astronomy Observatory

Quotes: VLBA orbited the planet with small, cool stars (2020, 4 August) from 5 August 2020 https://phys.org/news/2020-08-vlba-planet-orbiting-small-cool.html.

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