Goettingen: Super-Earths Discovered Orbiting Nearby Red Dwarf

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Goettingen: Super-Earths Discovered Orbiting Nearby Red Dwarf

Post by bystander » Fri Jun 26, 2020 2:56 pm

Super-Earths Discovered Orbiting Nearby Red Dwarf
Georg August University of Göttingen | 2020 Jun 25

International researchers led by University of Göttingen find multiple planet system orbiting Gliese 887

The nearest exoplanets to us provide the best opportunities for detailed study, including searching for evidence of life outside the Solar System. In research led by the University of Göttingen, the RedDots team of astronomers has detected a system of super-Earth planets orbiting the nearby star Gliese 887, the brightest red dwarf star in the sky. Super-Earths are planets which have a mass higher than the Earth’s but substantially below those of our local ice giants, Uranus and Neptune. The newly discovered super-Earths lie close to the red dwarf’s habitable zone, where water can exist in liquid form, and could be rocky worlds. ...

The RedDots team of astronomers monitored the red dwarf, using the HARPS spectrograph at the European Southern Observatory in Chile. They used a technique known as “Doppler wobble”, which enables them to measure the tiny back and forth wobbles of the star caused by the gravitational pull of the planets. The regular signals correspond to orbits of just 9.3 and 21.8 days, indicating two super-Earths – Gliese 887b and Gliese 887c – both larger than the Earth yet moving rapidly, much faster even than Mercury. Scientists estimate the temperature of Gliese 887c to be around 70°C.

A Multiple Planet System of Super-Earths Orbiting
the Brightest Red Dwarf Star GJ 887
~ Sandra Jeffers et al
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

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ASU: Planets Not as Safe from Stellar Flares as First Thought

Post by bystander » Tue Aug 25, 2020 3:35 pm

Recently Discovered Planets Not as Safe
from Stellar Flares as First Thought

Arizona State University, Tempe | 2020 Aug 25
A nearby star, the host of two (and possibly three) planets, was initially thought to be quiet and boring. These attributes are sought-after as they create a safe environment for their planets, especially those that may be in what scientists call “the habitable zone” where liquid water could exist on their surfaces and life might be possible. But astronomers at Arizona State University have announced that this nearby star turns out to be not so tame after all.

This star, named GJ 887, is one of the brightest M stars in the sky. M stars are low-mass red stars that outnumber stars like our sun more than tenfold, and the vast majority of planets in our galaxy orbit them.

GJ 887 had initially been spotlighted for the apparently gentle space environment it provides to its recently discovered planets. In monitoring by NASA’s Transiting Exoplanet Survey Satellite (TESS), a mission to search for planets outside our solar system, the star oddly exhibited no detectable flares over 27 days of continuous observations.

And an absence of flares is a quality that favors the survival of atmospheres on planets orbiting the star, and therefore potential life on those planets. ...

Because there are so many of them, M stars like GJ 887 are a key player in humanity's quest to understand where Earth fits into the grand menagerie of planets in the universe and in the search for life on other planets. ...

But there is a catch. M stars are prone to peppering their planets with flares. They can also be two-faced, appearing calm in visible light, like that observed by the TESS mission. In reality, they can be rife with flares that are clearly apparent in ultraviolet light, which has photons (particles of light) of much greater energy than visible light. And each flare has the potential to bombard the star's planets with a magnetic storm and a shower of fast-moving particles, increasing the chances that the atmospheres of GJ 887's planets were eroded away long ago. ...

When "Boring" Stars Flare: The Ultraviolet Activity of GJ 887,
a Bright M Star Hosting Newly Discovered Planets
~ R. O. Parke Loyd et al
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor