Gliese 581 g

from Wikipedia, the free encyclopedia

Gliese 581 g is the name of a proposed exoplanet around Gliese 581 , which, according to recent analyzes, probably does not exist.

history

Announcement

The discovery of Gliese 581 g was announced in September 2010. The analysis was based on 122 observations of the radial velocity of the star Gliese 581 over a period of 11 years with the HIRES spectrometer from the Keck Observatory on Mauna Kea , Hawaii , which were combined with observations from the HARPS spectrograph from the La Silla Observatory . Doubts about the alleged existence arose early on. Finally it could be shown that the statistical analysis in the publication of the discovery shows inadequacies.

Claimed properties

The claimed mass of the exoplanet was at least 3.1  Earth masses with an assumed upper limit of approximately 4.3 Earth masses; the orbit should have a major semi-axis of about 0.15  AU and an orbit period of just under 37 days. This would mean that it would be in the habitable zone and could potentially dispose of liquid water, although a bound rotation would be likely. It has also been called possibly the most Earth-like exoplanet known to date.

Reanalysis of the data

A further analysis of the data by other scientists, published on January 5, 2011, could not confirm the existence of an exoplanet with the claimed properties. For this purpose, models for a theoretical planetary model of one to six planets were simulated. The analysis of the HARPS data shows that five planets can be detected with relative certainty. The data for Gliese 581 b – e are plausible, those for Gliese f are still uncertain. No clue could be found for a sixth planet. The HARPS data thus exclude Gliese 581 g with the originally published values.

Since shifts in the light spectrum can also be caused by processes on the star itself, such as magnetic eruptions or large sunspots , Paul Robertson and colleagues from the Pennsylvania State University in University Park analyzed the spectral data of Gliese 581 again in 2014 , and also analyzed shifts out of the signal due to stellar activity. As a result, the signals for the previously suspected two Earth-like planets Gliese 581 g and Gliese 581 d disappeared and could no longer be distinguished from the background noise. For the red dwarf Gliese 581, based on these findings, only three planets can be considered as proven instead of six, none of which is a life-friendly earth twin.

Individual evidence

  1. ↑ The Lick-Carnegie Exoplanet Survey: A 3.1 M ⊕ Planet in the Habitable Zone of the Nearby M3V Star Gliese 581. (PDF (1.5 MB)) University of California , accessed on October 15, 2010 (English).
  2. ↑ Markus Becker: Controversy: Doubts about the existence of life-friendly planets. Spiegel Online , October 14, 2010, accessed October 15, 2010 .
  3. ^ Andrae et al .: Dos and donts of reduced chi-squared . December 16, 2010, arxiv : 1012.3754 .
  4. ^ Keck Observatory discovers the first Goldilocks exoplanet. WM Keck Observatory , September 29, 2010, accessed October 15, 2010 .
  5. ↑ Cornell University (Ed.): Bayesian Re-analysis of the Gliese 581 Exoplanet System . arxiv : 1101.0800 .
  6. ↑ Earth twins exposed as a deception. Magnetic turbulence on the red dwarf simulated the signal from two super-earths . On: scinexx.de from July 4, 2014.
  7. ↑ Paul Robertson, Suvrath Mahadevan, Michael Endl, Arpita Roy: Stellar activity masquerading as planets in the habitable zone of the M dwarf Gliese 581 . In: Science . July 2014. doi : 10.1126 / science.1253253 . Retrieved July 4, 2014.