From European Southern Observatory via Discover: “Three New Exoplanets Have Been Discovered Around a Nearby Star”

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From European Southern Observatory

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DiscoverMag

Discover Magazine

August 21, 2019
Mara Johnson-Groh

There is a triplet of Earth-sized planet candidates orbiting a star just 12 light-years away, a new study has found. And one appears to be in the habitable zone.

All three candidates are thought to be at least 1.4 to 1.8 times the mass of Earth, and orbit the star every three to 13 days, which would put the entire system well within Mercury’s 88 day orbit of the Sun. The planet orbiting the star every 13 days, dubbed planet d, is most interesting to scientists — it falls within the star’s habitable zone where liquid water could exist on the surface.

Exploring Our Neighborhood

“We are now one step closer [to] getting a census of rocky planets in the solar neighborhood,” said Ignasi Ribas, co-author on the new paper [MNRAS] and researcher at the Institute of Space Sciences in Barcelona, Spain.

The planets’ host is GJ 1061, a type of low-mass star called an M dwarf that is the 20th nearest star to the Sun. The star is similar to Proxima Centauri, the star closest to Earth, which was discovered to host a planet in 2016. GJ 1061, however, shows less violent stellar activity, suggesting that it might currently provide a safer environment for life than Proxima Centauri.

But to assess habitability, a star’s whole history needs to be accounted for and M dwarf stars could have had stronger activity levels in the past and also have much longer lifetimes than Sun-like stars. This means that a close-orbit planet, like planet d, may have spent many millions of years being blasted by intense radiation from its star, so it may not retain a life-sustaining atmosphere.

The new planets were discovered with the radial velocity method — a technique that uses tiny wobbles in a star’s orbit to revel the gravitational presence of exoplanets.

Radial Velocity Method-Las Cumbres Observatory

Radial velocity Image via SuperWasp http:// http://www.superwasp.org/exoplanets.htm

This technique typically reveals giant exoplanets close to their host star, but increasingly, this method is being used in long-term campaigns to reveal smaller exoplanets.

Using the HARPS instrument on the 3.6-meter telescope at the European Southern Observatory in La Silla, Chile [below], astronomers observed the star over 54 nights from July to September in 2018.

ESO/HARPS at La Silla


ESO 3.6m telescope & HARPS at Cerro LaSilla, Chile, 600 km north of Santiago de Chile at an altitude of 2400 metres.

The star was one target of a larger campaign called the Red Dot project, which since 2017 has surveyed small nearby stars to look for terrestrial planets like Earth.

ESO Pale Red Dot project

The data showed the signatures of three, and possibly four, candidate planets. The scientists suspect the fourth signal is just stellar activity — not a real planet. But after calculating the remaining three planets’ orbits, the scientists could not rule out an additional, unseen fourth planet. This undiscovered planet would have a much longer orbit, so further observations would be need to determine if there really is a fourth planet farther out.

See the full article here .


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ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre EEuropean Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

ESO/Cerro LaSilla, 600 km north of Santiago de Chile at an altitude of 2400 metres.

ESO VLT at Cerro Paranal in the Atacama Desert

ESO VLT 4 lasers on Yepun

Glistening against the awesome backdrop of the night sky above ESO_s Paranal Observatory, four laser beams project out into the darkness from Unit Telescope 4 UT4 of the VLT.

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

ESO/E-ELT,to be on top of Cerro Armazones in the Atacama Desert of northern Chile. located at the summit of the mountain at an altitude of 3,060 metres (10,040 ft).

A novel gamma ray telescope under construction on Mount Hopkins, Arizona. a large project known as the Cherenkov Telescope Array, composed of hundreds of similar telescopes to be situated in the Canary Islands and Chile. The telescope on Mount Hopkins will be fitted with a prototype high-speed camera, assembled at the University of Wisconsin–Madison, and capable of taking pictures at a billion frames per second. Credit: Vladimir Vassiliev