Artist’s impression of the newly discovered multiplanetary system of super-Earths orbiting the red dwarf Gliese 887. Credit: Mark Garlick
An international team of researchers has found multiple planetary systems orbiting the red dwarf star Gliese 887.
The international team “RedDots”, along with Australian astronomers from UNSW Sydney, Macquarie University and the University of South Queensland for this work, have detected a system of super-Earth planets orbiting the brightest red dwarf star in the Heaven, Gliese 887. The results were published in the journal Science on June 25, 2020.
The super-Earths are planets more massive than Earth, but substantially less massive than our local ice giants, Uranus and Neptune. The newly discovered super-Earths could be rocky worlds and be close to the “habitable zone” of this red dwarf star, that is, the zone where water could exist in liquid form on a planetary surface.
“The exciting thing about these planets is that they orbit a star that is so close to the Sun and so bright,” said UNSW-based planet hunter Professor Chris Tinney, co-author of the article. “We now know of thousands of Super-Earth-mass planets, or smaller ones. But most of those planets orbit faint, distant stars. Planets that orbit around nearby stars are key to future telescope searches for both exoplanet atmospheres, and eventually evidence of life. “
The team of astronomers monitored the red dwarf, using the Harps spectrograph at the European Southern Observatory in Chile, and then combined that data with data from the Anglo-Australian Planet Search (using the 3.9m Anglo-Australian Telescope near Coonabarabran), the planet-searching Spectrograph (at Cerro Las Campanas in Chile) and the Instruments contracted at the Keck telescopes in Maunakea, Hawaii.
Using a technique known as “Doppler wobble,” they measured Gliese 887’s small round-trip motion due to the gravitational pull of their planets. Regular signals correspond to orbital periods of 9.3 and 21.8 days, indicating the presence of two super-Earths, known as Gliese 887b and Gliese 887c. The team estimates that the surface temperature of the outer planet (Gliese 887c) is around 70orC.
Gliese 887 is about 11 light years away, making it one of the closest stars to the Sun. It is much dimmer and about half the size of our Sun. This means that its habitable zone is closer to Gliese 887, that the habitable zone of the Sun (in which the Earth orbits).
The team discovered some more interesting facts about Gliese 887 that turn out to be good news for both the newly discovered planets and the astronomers studying them.
“The red dwarf has little in the way of stars from other magnetic activities,” said Professor Brad Carter of the University of South Queensland. “If Gliese 887 were as active as many other red dwarf stars, its stellar winds and activity would likely significantly erode any planetary atmosphere. So since the star is relatively dormant, the newly discovered planets could be expected to retain their atmospheres. ”
“The star Gliese 887 is also very stable,” said Professor Rob Wittenmyer, also from the University of South Queensland. “The brightness of the Gliese 887 is really very constant. This will make it much easier to detect the atmospheres of these super-Earths using upcoming space facilities like the James Webb Space Telescope – The successor to the Hubble telescope, to be launched soon. “
“In the space age exoplanethunting telescopes like POTKepler and TESS“This result shows that astronomy from the ground continues to play a crucial role in our understanding of the planets in our local neighborhood,” said Dr. Simon O’Toole, co-author of the Macquarie University study.
Dr. Sandra Jeffers of the University of Göttingen and lead author of the study said, “These planets will provide the best possibilities for more detailed studies, including searching for life outside our Solar System.”
Read Super Earths Discovered In Orbit Near Red Dwarf Gliese 887 To Learn More About This Discovery.
Reference: “A system of multiple super-Earth planets orbiting the brightest red dwarf star GJ887” by SV Jeffers, S. Dreizler, JR Barnes, CA Haswell, RP Nelson, E. Rodríguez, MJ López-González, N. Morales, R. Luque, M. Zechmeister, SS Vogt, JS Jenkins, E. Palle, ZM Berdi ñas, GAL Coleman, MR Díaz, I. Ribas, HRA Jones, RP Butler, CG Tinney, J. Bailey, BD Carter, S O’Toole, RA Wittenmyer, JD Crane, F. Feng, SA Shectman, J. Teske, A. Reiners, PJ Amado and G. Anglada-Escudé, June 25, 2020, Science.
DOI: 10.1126 / science.aaz0795
