The progressive discovery of earth-like exo-planets

[shunyadragon]

I believe this star was previously considered as a candidate for earth-like exoplanets, but this research confirms that there are two earth-like planets,

International “RedDots” Team Has Detected a System of Super-Earth Planets Orbiting Nearby Red Dwarf Star

International “RedDots” Team Has Detected a System of Super-Earth Planets Orbiting Nearby Red Dwarf Star
TOPICS:AstronomyAstrophysicsExoplanetPopularUniversity Of New South Wales

By UNIVERSITY OF NEW SOUTH WALES JUNE 29, 2020


Artist’s impression of the multiplanetary system of newly discovered super-Earths orbiting nearby red dwarf Gliese 887. Credit: Mark Garlick

An international team of researchers has found multiple planet systems orbiting red dwarf star Gliese 887.

The international “RedDots” team – joined by Australian astronomers at UNSW Sydney, Macquarie University and University of Southern Queensland for this work – has detected a system of super-Earth planets orbiting the brightest red dwarf star in the sky, Gliese 887. The results were published in the journal Science on June 25, 2020.

Super-Earths are planets more massive than the Earth, but substantially less massive than our local ice giants, Uranus and Neptune. The newly discovered super-Earths could be rocky worlds, and lie close to the “habitable zone” of this red dwarf star – i.e. the zone where water could exist in liquid form on a planetary surface.

“The exciting thing about these planets are that they orbit a star so close to the Sun, and so very bright,” said UNSW-based planet hunter Prof Chris Tinney, who is a co-author on the paper. “We now know of thousands planets of Super-Earth-mass, or smaller. But most of those planets orbit distant and faint stars. Planets orbiting nearby stars are key for searches with future telescopes for both exoplanetary atmospheres, and eventually evidence for 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 finder Spectrograph (on Cerro Las Campanas in Chile) and the HIRES instrument on the Keck telescopes on Maunakea, Hawaii.

Using a technique known as “Doppler wobble,” they measured the tiny back and forth motion of Gliese 887 due to the gravitational pull of its planets. The regular signals correspond to orbital periods of 9.3 and 21.8 days, which indicates the presence of two super-Earths – known as Gliese 887b and Gliese 887c. The team estimates the surface temperature of the outer planet (Gliese 887c) to be around 70oC.

Gliese 887 is around 11 light years away, making it one of the closest stars to the Sun. It is much dimmer than, and about half the size of, our Sun. This means its habitable zone is closer to Gliese 887, than Sun’s habitable zone (in which the Earth orbits).

Dr. Sandra Jeffers, from the University of Göttingen and lead author of the study, said: “These planets will provide the best possibilities for more detailed studies, including the search for life outside our Solar System.”

Read Super-Earths Discovered Orbiting Nearby Red Dwarf Gliese 887 for more on this discovery.

Reference: “A multiple planet system of super-Earths orbiting the brightest red dwarf star GJ887” by S. V. Jeffers, S. Dreizler, J. R. Barnes, C. A. Haswell, R. P. Nelson, E. Rodríguez, M. J. López-Gonz’lez, N. Morales, R. Luque, M. Zechmeister, S. S. Vogt, J. S. Jenkins, E. Palle, Z. M. Berdi ñas, G. A. L. Coleman, M. R. Díaz, I. Ribas, H. R. A. Jones, R. P. Butler, C. G. Tinney, J. Bailey, B. D. Carter, S. O’Toole, R. A. Wittenmyer, J. D. Crane, F. Feng, S. A. Shectman, J. Teske, A. Reiners, P. J. Amado and G. Anglada-Escudé, 25 June 2020, Science.
DOI: 10.1126/science.aaz0795

 

[shunyadragon]

Another goldilocks planet found closer an earth like than ever before. . . but there is a problem. There are likely many earth-like planets everywhere, but at what stage are they in their development of their solar system. It depends on how mature the sun is. In our solar system both Venus and Mars were potentially living earth-like planets but no more. Earth-like planets have a life span as the sun matures, and eventually earth will no longer be a habitable earth-like planet.

Source: "Mirror Image" of the Earth and Sun Discovered 3000 Light-Years Away

“Mirror Image” of the Earth and Sun Discovered 3000 Light-Years Away
TOPICS:AstrobiologyAstronomyAstrophysicsExoplanetM ax Planck Institute
By MAX PLANCK SOCIETY JUNE 7, 2020

The star Kepler-160 and its companion KOI-456.04 are more reminiscent of the Sun-Earth system than any previously known exoplanet-star pair.

Among the more than 4,000 known exoplanets, KOI-456.04 is something special: less than twice the size of Earth, it orbits a Sun-like star. And it does so with a star-planet distance that could permit planetary surface temperatures conducive to life.

The object was discovered by a team led by the Max Planck Institute for Solar System Research in Göttingen. Its host star, called Kepler-160, actually emits visible light; the central stars of almost all other exoplanets, on the other hand, emit infrared radiation, are smaller and fainter than the Sun and therefore belong to the class of red dwarf stars.

Typical Exoplanets

Distant worlds: typical exoplanets orbiting around a Sun-like star are about the size of Neptune and are in close orbit (third picture from above). Almost all of the Earth-sized planets known to have potentially Earth-like surface temperatures are in orbit around red dwarf stars, which do not emit visible light but infrared radiation instead (bottom panel). The Earth is in the right distance from the Sun to have surface temperatures required for the existence of liquid water. The newly discovered planet candidate KOI-456.04 and its star Kepler-160 (second panel from above) have great similarities to Earth and Sun (top panel). Credit: MPS / René Heller

. . . .

“The full picture of habitability, however, involves a look at the qualities of the star too,” explains MPS scientist and lead author of the new study Dr. René Heller. So far, almost all exoplanets less than twice the size of Earth that have a potential for clement surface temperatures are in orbit around a red dwarf.

Red dwarf stars are known for their extremely long lifetimes. Life on an exoplanet in orbit around an old red dwarf star could potentially have had twice as much time than life on Earth to form and evolve. But the radiation from a red dwarf star is mostly infrared rather than visible light as we know it. Many red dwarfs are also notorious for emitting high-energy flares and for frying their planets, which would later become habitable, with enhanced stellar luminosities as long as these stars are young. Moreover, their faintness requires any habitable planet to be so close to the star that the stellar gravity starts to deform the planet substantially. The resulting tidal heating in the planet could trigger fatal global volcanism. All things combined, the habitability of planets around red dwarf stars is heavily debated in the scientific community.

In their new research article, the team of scientists from MPS, the Sonneberg Observatory, the University of Göttingen, the University of California in Santa Cruz, and from NASA now reports the discovery of a planet candidate less than twice the size of the Earth and with moderate illumination from a Sun-like star

At a distance of just over 3000 light-years from the solar system, the star Kepler-160 was located in the field of view of the Kepler primary mission and was continuously observed from 2009 to 2013. Its radius of 1.1 solar radii, its surface temperature of 5200 degrees Celsius (300 degrees less than the Sun), and its very Sun-like stellar luminosity make it an astrophysical portrayal of our own parent star.

Kepler-160 has been known for about six years to be a host star of two exoplanets, called Kepler-160b and Kepler-160c. Both of these planets are substantially bigger than Earth and in relatively close orbits around their star. Their surface temperatures would certainly make them hotter than a baking oven and everything but hospitable for life as we know it. But tiny variations in the orbital period of planet Kepler-160c gave scientists a signature of a third planet that had yet to be confirmed.

. . .

When searching for exoplanets, scientists usually look for repeating brightness variations of stars. These temporary dimmings, usually just one percent or less of the apparent stellar brightness, can be caused by planets transiting the disks of their host stars as seen from Earth. The key idea of Michael Hippke, co-author of the new work, and Heller was to use a detailed physical model of the stellar brightness variation instead of searching for a step-like jump-to-dimming and then jump-back-to-normal brightness pattern in stellar light curves.

This box-like approximation used to be the standard search technique for almost two decades. “Our improvement is particularly important in the search for small, Earth-sized planets,” Heller explains. “The planetary signal is so faint that it’s almost entirely hidden in the noise of the data. Our new search mask is slightly better in separating a true exoplanetary signal from the noise in the critical cases,” Heller adds.

Their new search algorithm was crucial for the discovery of the new transiting planet candidate KOI-456.04. “Our analysis suggests that Kepler-160 is orbited not by two but by a total of four planets,” Heller summarizes the new study. One of the two planets that Heller and his colleagues found is Kepler-160d, the previously suspected planet responsible for the distorted orbit of Kepler-160c. Kepler-160d does not show any transits in the light curve of the star and so it has been confirmed indirectly.

The other planet, formally a planet candidate, is KOI-456.04, probably a transiting planet with a radius of 1.9 Earth radii and an orbital period of 378 days. Given its Sun-like host star, the very Earth-like orbital period results in a very Earth-like insolation from the star – both in terms of the amount of the light received and in terms of the light color. Light from Kepler-160 is visible light very much like sunlight. All things considered, KOI-456.04 sits in a region of the stellar habitable zone – the distance range around a star admitting liquid surface water on an Earth-like planet – that is comparable to the Earth’s position around the Sun.

“KOI-456.01 is relatively large compared to many other planets that are considered potentially habitable. But it’s the combination of this less-than-double the size of the Earth planet and its solar type host star that make it so special and familiar,” Heller clarifies. As a consequence, the surface conditions on KOI-456.04 could be similar to those known on Earth, provided its atmosphere is not too massive and non-Earth-like. The amount of light received from its host star is about 93 percent of the sunlight received on Earth. If KOI-456.04 has a mostly inert atmosphere with a mild Earth-like greenhouse effect, then its surface temperature would be +5 degrees Celsius on average, which is about ten degrees lower than the Earth’s mean global temperature.

It cannot currently be ruled out completely that KOI-456.04 is in fact a statistical fluke or a systematic measurement error instead of a genuine planet. The team estimates the chances of a planetary nature of KOI-456.04 to be about 85% pro planet. Obtaining a formal planetary status requires 99%. While some of the Earth’s most powerful ground-based telescopes might be able to validate this candidate with observations of one of its upcoming transits, there is also a good chance that the PLATO space mission of ESA will be capable of a confirmation. PLATO is scheduled for launch in 2026 and one of its major science goals is the discovery of Earth-sized planets around Sun-like stars. The MPS is currently building the PLATO Data Center and deeply involved in the PLATO mission. If PLATO will be oriented in such a way as to re-observe the field of view of the Kepler primary mission, then KOI-456.04 will have a chance of being confirmed and studied in even more detail with PLATO.

Reference: “Transit least-squares survey: III. A 1.9 R⊕ transit candidate in the habitable zone of Kepler-160 and a nontransiting planet characterized by transit-timing variations” by René Heller, Michael Hippke, Jantje Freudenthal, Kai Rodenbeck, Natalie M. Batalha and Steve Bryson, 4 June 2020, Astronomy & Astrophysics.
DOI: 10.1051/0004-6361/201936929.

© Copyright Original Source

 

[sun rise]

The rate at which we're learning about the universe is fascinating.

 

[epronovost]

I can't wait for the James-Webb telescope to finally be deployed. It has been delayed so long.

 

[danieldemol]

using the 3.9m Anglo-Australian Telescope

Great article. It’s weird that we named the telescope after a race though.

 

[shunyadragon]

Multiplanet system around sunlike star photographed for 1st time ever | Space

Multiplanet system around sunlike star photographed for 1st time ever
By Mike Wall 3 hours ago

The two newly imaged planets are huge — 14 and 6 times more massive than Jupiter.

For the first time ever, astronomers have directly imaged multiple planets orbiting a sunlike star.

The European Southern Observatory's Very Large Telescope (VLT) in Chile photographed two giant planets circling TYC 8998-760-1, a very young analogue of our own sun that lies about 300 light-years from Earth, a new study reports.

our solar system, but at a much earlier stage of its evolution," study lead author Alexander Bohn, a doctoral student at Leiden University in the Netherlands, said in a statement.

Related: The strangest alien planets (gallery)

The two giant planets in the TYC 8998-760-1 system are visible as two bright dots in the center (TYC 8998-760-1b) and bottom right (TYC 8998-760-1c) of the frame, noted by arrows. Other bright dots, which are background stars, are visible in the image as well. By taking different images at different times, the team was able to distinguish the planets from the background stars. The image was captured by blocking the light from the young, sunlike star (top-left of center) using a coronagraph, which allows for the fainter planets to be detected. The bright and dark seen on the star’s image are optical artifacts. (Image credit: ESO/Bohn et al.)
Before this historic cosmic portrait, only two multiplanet systems had ever been directly imaged, and neither of them features a sunlike star, study team members said. And snapping a photo of even a single exoplanet remains a rare achievement.

The newly reported SPHERE imagery revealed two planets in the system, TYC 8998-760-1b and TYC 8998-760-1c. Astronomers already knew about TYC 8998-760-1b — a team led by Bohn announced its discovery late last year — but TYC 8998-760-1c is a newfound world.

"Even though astronomers have indirectly detected thousands of planets in our galaxy, only a tiny fraction of these exoplanets have been directly imaged," study co-author Matthew Kenworthy, an associate professor at Leiden University, said in the same statement.

Bohn, Kenworthy and their colleagues studied the 17-million-year-old star TYC 8998-760-1 with the VLT's Spectro-Polarimetric High-contrast Exoplanet Research instrument, or SPHERE for short. SPHERE uses a device called a coronagraph to block a star's blinding light, allowing astronomers to see and study orbiting planets that would otherwise be lost in the glare.

Neat pictures.