SCI Mystery signals in space suggests Earth-like planet exists (GJ 581d)

[Housecarl]

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http://www.dnaindia.com/scitech/rep...ace-suggests-earth-like-planet-exists-2066947

Mystery signals in space suggests Earth-like planet exists
Sunday, 8 March 2015 - 12:56pm IST Updated: Sunday, 8 March 2015 - 12:40pm IST | Place: London | Agency: ANI

Astronomers now believe that the mysterious signals, previously dismissed as stellar bursts, are indeed coming from an Earth-like planet.

Astronomers now believe that the mysterious signals, previously dismissed as stellar bursts, are indeed coming from an Earth-like planet.

Discovery of the planet known as GJ 581d was heralded in 2007, but new research in 2014 cast doubt on the claims, saying data used to find it was probably just misinterpreted signals from stars, the Independent reported.

Astronomers used a spectrometer to spot the planet, which measures "wobbles" in the wavelength of light emitted by a star caused as a planet orbits it. GJ 581d was said to be a super-Earth with a mass seven times that of our own planet orbiting a red dwarf star that could also support up to four other planets. The Habitable Exoplanets Catalogue currently records 23 objects of interest.

It was believed to be in the habitable "Goldilocks zone" in its solar system, where it is neither too hot nor too cold for liquid water to exist and support life on the surface.

Researchers revisiting the evidence claimed the body was actually just "stellar activity masquerading as planets" and its existence was widely dismissed without further questioning. However, now astronomers from Queen Mary University, in London, and the University of Hertfordshire have claimed the statistical techniques used to discount GJ 581d was "inadequate" for planets of its small size.

If GJ 581d does exist, it could be the most Earth-like planet yet discovered as ranked by the Earth Similarity Index but that does not mean its surface is the same. Some studies have suggested Gliese 581d's denser air and dim red light from its host star would make for a murky environment that would be toxic to humans.

The Index incorporates a number of factors including surface temperature and planet density to rank extrasolar planets in a scale from 0 to 1. The most Earth-like planet yet confirmed was Gliese 581g, orbiting the same star, which ranks at 0.89. For astronomers, the most exciting aspect is its relative proximity, 20 light years away in a galaxy that was 100,000 light years wide.

The study is published in Science.

 

[Housecarl]

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http://marketbusinessnews.com/earth...years-away-does-exist-say-uk-scientists/51564

Earth-like planet 20m light years away does exist, say UK scientists
March 8, 2015, 4:32 AM CST | Written by Christian Nordqvist

In 2014, scientists discarded mysterious signals pointing to an Earth-like planet 20 million light years away as just noise in the data caused by starspots and ignored it. British scientists say the planet, known as GJ 581d, does exist and that the previous method was no good at finding smaller exoplanets.

The planet orbits a red dwarf called Gliese 581 in the constellation Libra. A red dwarf is a small and relatively cool star. The planet is in the Habitable Zone, known informally as the Goldilocks Zone, because given its distance from its sun and the likelihood of having an atmosphere and liquid water, conditions could be “just right” for there being life there.

In this latest study, carried out by scientists from Queen Mary University of London and the University of Hertfordshire, and published in the academic journal Science, the methods previously used to detect the planet and then rule it out are challenged.

The planet candidate was initially detected using a spectrometer which gauges the tiny changes in the wavelength of light emitted by a star. This is caused when orbiting planets move in front of it (the “wobble”).

In 2014, planet scientists who revisited the data collected in 2007 concluded that there was nothing there and what they were looking at was simply noise in the data caused by starspots (sunspots located on other stars). They were certain their conclusion was right and the matter seemed settled…, until now.

Old method cannot detect smaller planets

The statistical technique used in 2014 to account for stellar activity was “simply inadequate for identifying small planets like GJ 581d,” the researchers say.

The old method is fine when you are seeking out larger planets, because their wobble effect is so great than all other possible errors are negated. However, it is no good for finding small planets that are close to or within the noise caused by the star’s own variability.

After looking at the data again using a more accurate model, lead author Dr. Guillem Anglada-Escudé and colleagues say they are “highly confident” that GJ 581d is a real planet, despite starspot noise.

Dr. Anglada-Escudé, said:

“The existence, or not, of GJ 581d is significant because it was the first Earth-like planet discovered in the ‘Goldilocks’-zone around another star and it is a benchmark case for the Doppler technique.”

“There are always discussions among scientists about the ways we interpret data but I’m confident that GJ 581d has been in orbit around Gliese 581 all along. In any case, the strength of their statement was way too strong. If they way to treat the data had been right, then some planet search projects at several ground-based observatories would need to be significantly revised as they are all aiming to detect even smaller planets. One needs to be more careful with these kind of claims.”

GJ 581d might be very Earth-like

If the latest study proves true and GJ 581d really does exist, it might be one of the most Earth-like planets discovered so far, as ranked by the Earth Similarity Index. However, its surface may be quite different.

http://marketbusinessnews.com/wp-content/uploads/2015/03/Keplers-habitable-planets.jpg
NASA’s Kepler Space Telescope has detected more than 1,000 planets. Eight of them are less than twice Earth-size and within their stars’ habitable zone. (Image: NASA Kepler’s Hall of Fame)

According to some studies, the atmosphere in GJ 581d is much denser than ours, while the dim light of its dwarf star would make for a gloomy environment that would be toxic for humans.

The Earth Similarity Index incorporates several factors, such as surface temperature, planet density, and the possibility of there being liquid water, in a scale of 0 to 1 (Earth is 1). GJ 581d is the most Earth-like planet yet detected, with an estimated Index of 0.89.

Citation: Guillem Anglada-Escudé and Mikko Tuomi. “Comment on ‘Stellar activity masquerading as planets in the habitable zone of the M dwarf Gliese 581′,” Science. Published on 6th March, 2015. DOI:10.1126/science.1260796.

Video – GJ 581d

 

[Housecarl]

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http://www.piercepioneer.com/astronomers-just-discover-not-new-habitable-planet/38617

Did Astronomers Just Discover A [Not-So] New, Habitable Planet?
by Deborah Grace
March 8, 2015

Astronomers have “rediscovered” a “new” planet that they used to believe was not capable of hosting life but perhaps technology has changed—or our understanding of the universe—because now they say that it may be in that coveted “Goldilocks zone” within its solar system.

And just fyi, Earth is in the Solar System’s “Goldilocks zone.”

But back to the new evidence regarding the old discovery.

The planet has been dubbed GJ 581d. It is not too hot and not too cold in its solar system, which means that liquid water could exist there and, furthermore, life as we know it.

“The existence (or not) of GJ 581d is significant because it was the first Earth-like planet discovered in the ‘Goldilocks’-zone around another star and it is a benchmark case for the Doppler technique,” explains lead author Dr Guillem Anglada-Escud. “There are always discussions among scientists about the ways we interpret data but I’m confident that GJ 581d has been in orbit around Gliese 581 all along.”

However, the Penn State University scientists who originally discovered the planet argue: “Our work clearly established the rotation period of GJ 581 to be 130 days—twice the period of ‘planet d’—independently of the statistical arguments raised in the Comment. Without compelling evidence otherwise, a periodic RV signal at the stellar rotation period or its integer fractions should be assumed to be associated with stellar activity instead of a planet.”

Researcher Amy R. Connolly continues, “As recently noted by the High Accuracy Radial Velocity Planet Searcher (HARPS) team — who originally discovered “planet d” — had the rotation period of GJ 581 been previously known, it is unlikely that the 66-day RV signal would ever have been ascribed to an exoplanet.”

 

[The Mountain]

Just so everyone's clear: The planet is not EMITTING signals. The signals talked about in the OP are the fluctuations in light wavelengths used to DETECT the planet.

 

[Steel Chips]

"In 2014, scientists discarded mysterious signals pointing to an Earth-like planet 20 million light years away as just noise in the data caused by starspots and ignored it."

Christian Nordqvist is not a very bright reporter, is he?