Post by Andrei Tchentchik on Apr 5, 2019 12:43:27 GMT 2
(.#164).- KIC 8462852, the strange star, becomes ... even stranger.
KIC 8462852, the strange star, becomes ... even stranger.
Xavier Demeersman
Journalist.
The strange and erratic variations of brightness of the star KIC 8462852, which had ignited wild speculations about extraterrestrials, are still far from having found an explanation. The hypothesis of a gigantic comet ballet no longer holds, says a new study that looks back on 100 years of observation. For a long time, this star has been behaving strangely. So what ? A mystery.
The hypothesis of giant comets passing KIC 8462852 does not seem to resist the arguments of a new study. © Nasa, JPL-Caltech
Star KIC 8462852 has not finished talking about her. In previous episodes of this thriller series that began publicly in September 2015, we saw that the team of Tabetha Boyajian, Yale University, investigated the strange case of this star distant a little over 1,400 years -light, nicknamed since Tabby in reference to the young astrophysicist, very intrigued by the erratic variations of its brightness.
Indeed, the star that was in the nets of Kepler, famous satellite hunter of exoplanets by the method of transit (when one or more planets pass in front of their star, it slightly bends its intrinsic luminosity), shows significant decreases and aperiodic of its brightness, sometimes up to 22% for several days, without it being possible, for the moment, to determine the cause (s).
The various scenarios proposed
In an attempt to explain this behavior naturally, several possible causes have been considered. Would it be an exoplanet? The hypothesis does not hold water as the measurements indicate. Even though it was bigger than Jupiter, it could not bend the light of KIC 8462852 beyond 1%. Perhaps they are disturbances on the surface of the star? There is no more, say the astronomers. Belonging to the main sequence of spectral class F3 (a little bigger and warmer than our Sun), its luminosity is considered very stable and it should not know of a change of regime before tens of millions of years.
Star KIC 8462852 photographed in October 2015. © Efraín Morales, Astronomical Society of the Caribbean (SAC)
Could there have been a technical problem with the satellite? No more, everything has been checked. Finally, the scenario of vast cold clouds of gas and dust, asteroid debris after violent collisions or the presence of a protoplanetary disk were in turn discarded due to the lack of signatures in the infrared at later observations. with Spitzer and Wise. "[This absence] two years after the events behind the unusual light curve observed with Kepler further disrupts scenarios that involve a catastrophic collision within an asteroid belt, a giant impact disrupting a planet's system. or a population of dust-covered planetesimals, "said Massimo Marengo, associate professor at Iowa State University.
Finally, the team concluded that the only natural explanation that resists and matches what was observed is that of a procession of giant comets in transit. An alternative was however issued by some colleagues, not without sparking a tsunami of comments throughout the world: and if these anomalies of luminosity were rather produced by the activities of a possible extraterrestrial civilization? For example, a sphere of Dyson under construction, aiming to collect the energy of the star, or possibly a Matryoshka brain.
In this perspective, the Seti institute listened several times to KIC 8462852, without being able to say that there is no emission of artificial origin from this region of the Milky Way.
The hypothesis of comets is in turn rejected
The drama is far from over. The investigation continues and this time, the astronomers searched in the past of the star, to see if these variations of light are exceptional - after all, Kepler could have looked just at the moment when the comets passed in front ... - or if they are frequent and regular.
Since Kepler only observed in this direction between 2009 and 2013, Bradley E. Schaefer (University of Louisiana), who submitted his study to The Astrophysical Journal Letters (available on Arxiv), had to find another way to question the past of the offending star. To do this, he has scanned the digitized photographic plates of this region of the constellation Cygnus testifying to a century of observation, from 1890 to 1989. He discovered that Tabby had its brightness that has several times declined. around 20 %. The author writes, "The light curve of KIC 8462852 shows a very strong secular trend in its brightness drop over more than 100 years, which is quite unprecedented for any type F star in the sequence principal ". These anomalies are therefore not only the preserve of Kepler. We can therefore exclude any artefacts from the satellite, given the continuity of the phenomenon.
This finding is not without problem in the scenario of a flotilla of comets. "With 36 giant comets in an orbit that would cause a single 20% drop in brightness as seen with Kepler, it would take 648,000 giant comets to create comparable declines throughout a century," says Bradley E. Schaefer. Their mass would be equivalent to that, total, of the Kuiper belt. "I do not see how it is possible for something like 648,000 giant comets [about 200 km in diameter each, Ed] to exist around a star, while having their orbits orchestrated so that they all pass in front of the star in the last century, "argues the researcher who concludes that this secular variation goes against the hypothesis of a family of comets.
The discoverers of this strange case admit that these results are disturbing and that the problem is not solved, which does not exclude obviously a natural explanation. Remember pulsars at first confused with a signal of an extraterrestrial civilization (the famous signal Wow!). In short, the suspense continues and, in any case, KIC 8462852 has great surprises!
F I N .
KIC 8462852, the strange star, becomes ... even stranger.
Xavier Demeersman
Journalist.
The strange and erratic variations of brightness of the star KIC 8462852, which had ignited wild speculations about extraterrestrials, are still far from having found an explanation. The hypothesis of a gigantic comet ballet no longer holds, says a new study that looks back on 100 years of observation. For a long time, this star has been behaving strangely. So what ? A mystery.
The hypothesis of giant comets passing KIC 8462852 does not seem to resist the arguments of a new study. © Nasa, JPL-Caltech
Star KIC 8462852 has not finished talking about her. In previous episodes of this thriller series that began publicly in September 2015, we saw that the team of Tabetha Boyajian, Yale University, investigated the strange case of this star distant a little over 1,400 years -light, nicknamed since Tabby in reference to the young astrophysicist, very intrigued by the erratic variations of its brightness.
Indeed, the star that was in the nets of Kepler, famous satellite hunter of exoplanets by the method of transit (when one or more planets pass in front of their star, it slightly bends its intrinsic luminosity), shows significant decreases and aperiodic of its brightness, sometimes up to 22% for several days, without it being possible, for the moment, to determine the cause (s).
The various scenarios proposed
In an attempt to explain this behavior naturally, several possible causes have been considered. Would it be an exoplanet? The hypothesis does not hold water as the measurements indicate. Even though it was bigger than Jupiter, it could not bend the light of KIC 8462852 beyond 1%. Perhaps they are disturbances on the surface of the star? There is no more, say the astronomers. Belonging to the main sequence of spectral class F3 (a little bigger and warmer than our Sun), its luminosity is considered very stable and it should not know of a change of regime before tens of millions of years.
Star KIC 8462852 photographed in October 2015. © Efraín Morales, Astronomical Society of the Caribbean (SAC)
Could there have been a technical problem with the satellite? No more, everything has been checked. Finally, the scenario of vast cold clouds of gas and dust, asteroid debris after violent collisions or the presence of a protoplanetary disk were in turn discarded due to the lack of signatures in the infrared at later observations. with Spitzer and Wise. "[This absence] two years after the events behind the unusual light curve observed with Kepler further disrupts scenarios that involve a catastrophic collision within an asteroid belt, a giant impact disrupting a planet's system. or a population of dust-covered planetesimals, "said Massimo Marengo, associate professor at Iowa State University.
Finally, the team concluded that the only natural explanation that resists and matches what was observed is that of a procession of giant comets in transit. An alternative was however issued by some colleagues, not without sparking a tsunami of comments throughout the world: and if these anomalies of luminosity were rather produced by the activities of a possible extraterrestrial civilization? For example, a sphere of Dyson under construction, aiming to collect the energy of the star, or possibly a Matryoshka brain.
In this perspective, the Seti institute listened several times to KIC 8462852, without being able to say that there is no emission of artificial origin from this region of the Milky Way.
The hypothesis of comets is in turn rejected
The drama is far from over. The investigation continues and this time, the astronomers searched in the past of the star, to see if these variations of light are exceptional - after all, Kepler could have looked just at the moment when the comets passed in front ... - or if they are frequent and regular.
Since Kepler only observed in this direction between 2009 and 2013, Bradley E. Schaefer (University of Louisiana), who submitted his study to The Astrophysical Journal Letters (available on Arxiv), had to find another way to question the past of the offending star. To do this, he has scanned the digitized photographic plates of this region of the constellation Cygnus testifying to a century of observation, from 1890 to 1989. He discovered that Tabby had its brightness that has several times declined. around 20 %. The author writes, "The light curve of KIC 8462852 shows a very strong secular trend in its brightness drop over more than 100 years, which is quite unprecedented for any type F star in the sequence principal ". These anomalies are therefore not only the preserve of Kepler. We can therefore exclude any artefacts from the satellite, given the continuity of the phenomenon.
This finding is not without problem in the scenario of a flotilla of comets. "With 36 giant comets in an orbit that would cause a single 20% drop in brightness as seen with Kepler, it would take 648,000 giant comets to create comparable declines throughout a century," says Bradley E. Schaefer. Their mass would be equivalent to that, total, of the Kuiper belt. "I do not see how it is possible for something like 648,000 giant comets [about 200 km in diameter each, Ed] to exist around a star, while having their orbits orchestrated so that they all pass in front of the star in the last century, "argues the researcher who concludes that this secular variation goes against the hypothesis of a family of comets.
The discoverers of this strange case admit that these results are disturbing and that the problem is not solved, which does not exclude obviously a natural explanation. Remember pulsars at first confused with a signal of an extraterrestrial civilization (the famous signal Wow!). In short, the suspense continues and, in any case, KIC 8462852 has great surprises!
F I N .
