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In astronomy this week, TESS finds its first exoplanet – a super-Earth around the nearby star Pi Mensae – and astronomers have seen an asteroid hiding a galaxy to get details on size, shape and shape. orbit of the asteroid.
TESS Satellite spots its first planet
A team of scientists working with new data from the Transiting Exoplanet Survey (TESS) satellite has announced the discovery of a super-Earth in orbit around the star Pi Mensae.
The star, located 60 light-years from the constellation Mensa, is visible to the naked eye under a clear, dark sky of magnitude 5.7. The star was already known to host a planet 10 times the mass of Jupiter in an oval-shaped orbit of 5.7 years. Now Chelsea Huang (MIT) and his colleagues have found another planet in the same system that is twice the size of the Earth.
As TESS was monitoring star-type Sun Pi Mensae, it experienced a drop in brightness every 6.27 days, indicating a second planet in the system. (A distant planet ten times the mass of Jupiter had been discovered more than ten years earlier.)
Huang et al. / arXiv.org
With the detection of TESS in hand, the team took over the archival data collected by the Anglo-Australian telescope and the HARPS instrument at the La Silla Observatory in Chile, confirming the existence of the planet and reducing its mass between 4 and 5.7 times that of Earth. Based on its average density, this super-Earth probably has a rocky core or iron surrounded by an atmosphere of light molecules, such as hydrogen, helium, water or methane.
The atmosphere of the planet is probably too close to the surface of the planet for a lot of starlight to pass through, so study it further via transit spectroscopy will be difficult at best. But the proximity of the planet and the brightness of the star make the system a promising target for other studies. TESS has just started its mission – its all-sky survey began on July 25 and has only released its first image this week – so expect many more results.
Learn more about Pi Mensae c in the journal that the team posted on Sept. 16 on the preprint server arXiv.org.
An asteroid hides a galaxy
On May 15, 2017, an asteroid in the main belt blocked the radio waves of a distant galaxy. However, in a process called diffraction, the waves bent around the asteroid and interacted to form a pattern of light and dark circles. Astronomers have analyzed this model to learn new details about the asteroid. size, shape and orbit.
Bill Saxton / NRAO / AUI / NSF
When the asteroid of the main belt 372 Palma crossed a galaxy on May 15, 2017, astronomers were ready and waiting. The supermassive black hole in the center of the galaxy, known as the TXS 0141 + 268, emits a radio jet almost directly to Earth. As the next asteroid passed in front of the jet, it was blocking the radio signal – mainly. Radio waves jumping from the edge of the asteroid produced a diffraction pattern allowing Jorma Harju (University of Helsinki, Finland) and her colleagues to measure the size, shape, and orbit of l & # 39; asteroid.
The measurement was made by comparing observations when the shadow of the radio crossed the United States at 51 kilometers per second (120,000 mph). Shadow has passed through a radio antenna in Brewster, Washington, which is part of the VLBA (Very Long Baseline Array) chart, but has avoided other VLBA dishes in California, Texas , Arizona and New Mexico. The analysis of the different observations confirmed the size and shape of Palma (192 kilometers wide and oblate) and an orbit calculation 10 times more accurate than the previous observations allowed.
To find out more in the VLBA press release and in the document to be published in the Astronomical Journal.
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