Thousands of exoplanets have been discovered so far, of many different types, but they all share one thing in common: they have all been found in our own galaxy. This is not surprising however, since of course they would be easier to detect than ones even farther away. But now, astronomers have reported the discovery of the first possible exoplanets in another galaxy, an incredible accomplishment, especially considering that the galaxy is 3.8 billion light-years away!
Astronomers just announced the discovery of yet another exoplanet, just one of thousands now, but this one is quite interesting and exciting for a variety of reasons. The planet, called Ross 128 b, is an Earth-sized world orbiting a star only 11 light-years away. Not only is it nearly the same size as Earth, the observations show that it is likely quite temperate, with temperatures similar to those on our planet as well. These findings make it possibly the best exoplanet candidate yet in the search for extraterrestrial life.
Ross 128 b was discovered by astronomers using the High Accuracy Radial velocity Planet Searcher (HARPS) at the La Silla Observatory in Chile, which is operated by the European Southern Observatory (ESO).
“This discovery is based on more than a decade of HARPS intensive monitoring together with state-of-the-art data reduction and analysis techniques. Only HARPS has demonstrated such a precision and it remains the best planet hunter of its kind, 15 years after it began operations,” said Nicola Astudillo-Defru from the Geneva Observatory – University of Geneva, Switzerland), who co-authored the discovery paper.
The planet orbits the red dwarf star Ross 128 every 9.9 days. Even though it orbits so close to the star, temperatures are calculated to be temperate, since the star is a lot smaller and cooler than our Sun. There is still some debate as to whether the planet is actually inside the “habitable zone” of the star, where liquid water could most likely exist on the surface, but what astronomers have learned so far makes them optimistic that the planet could be quite potentially habitable. Since Ross 128 b receives only 1.38 times more irradiation than the Earth, its equilibrium temperature is estimated to lie between -60°C and 20°C (-76°F and 68°F). Not bad.
Ross 128 b is now the second closest known Earth-sized temperate exoplanet. The one orbiting Proxima Centauri is closer, but that red dwarf star is more active than Ross 128, sending out frequent, intense flares which could adversely affect the habitability of any planets there. Ross 128 is much quieter.
Many exoplanets are now being discovered orbiting red dwarf stars, which are the most common stars in our galaxy. There are now estimated to be billions of planets in our galaxy alone.
Another interesting fact is that while Proxima Centauri is currently the closest star to us, apart from the Sun of course, Ross 128 is gradually moving closer and in about 79,000 years will become the closest star.
The discovery of Ross 128 b is raising some eyebrows for another reason as well – its star is the same one that was in the news this past spring and summer when SETI astronomers detected unusual radio signals coming from the direction of the star, first heard in May 2017. At the time, it was tentatively concluded that they were probably from an unknown satellite and not aliens, but this new discovery may prompt astronomers to take another look.
“So sadly, we’ve already looked closely at Ross 128 and have come up empty. Nonetheless, as Ross 128b is such an exciting target, we are considering additional, deeper observations at radio and optical wavelengths. Nearby exoplanets are particularly exciting from a SETI perspective as they permit us to search for and potentially detect much weaker signals than from more distant targets.”
Ross 128 b will also be a prime target for ESO’s upcoming Extremely Large Telescope (ELT), which would be capable of detecting possible biomarkers in its atmosphere such as oxygen. Other closer exoplanets will also be able to be studied in this way in the next few years, by ELT and other telescopes, perhaps bringing us closer than ever before to finding the holy grail of exoplanetology – another inhabited world.
The new research paper is available here.
This article was first published on Futurism.
Exoplanets, planets orbiting stars other than the Sun, are being discovered by the thousands now, and there are estimated to be billions of them in our galaxy alone. So far, they have ranged from worlds smaller than Earth, to “super-Earths” and “hot Jupiters” – a wide variety of sizes, compositions and temperatures. For many people, the most interesting are the ones which could potentially support life of some kind. How many of these planets may actually be habitable, at least by earthly standards? As technology improves, astronomers are getting closer to tentatively answer some of these questions, and a few dozen or so such planets have been identified so far. Now, a large team of researchers have found 20 more exoplanets which might be capable of supporting life. The findings are based on data sent back by NASA’s Kepler Space Telescope.
The planets were found by using a tool called a Robovetter to sift through the data and narrow down the the most interesting candidates.
It should also be noted that these are still planetary candidates, and further observations will be needed to fully confirm them. The great majority of exoplanet candidates do end up being confirmed, with relatively few being false positives.
Out of the candidates, two are in multi-planet systems and ten are near-Earth size, in the habitable zones of their stars.
One of the planets in particular stood out, KOI-7923.01, which was found to have an orbit of 395 days and was close to Earth in size. The planet is a little cooler than Earth due to its distance from its star, relative to Earth’s orbit, and the star being cooler than the Sun. Initial studies suggest that the planet is likely covered by a frozen tundra, but may not be too cold for life.
Many of the other planets have long orbits as well. To date, most of the exoplanets discovered so far have had shorter orbits closer to their stars, since they are the easiest to detect.
These new likely exoplanets were found in photometry data sent back by Kepler over four years, before the problems with the telescope’s reactor wheels which ended the primary mission in 2013. They were part of a catalogue of 8,054 “Kepler Objects of Interest” that were pared down to 4,034 exoplanets believed to have orbits between .25 and 632 days. Kepler, although hobbled, is currently in its K2 mission phase, observing different regions of stars than before.
Most of the exoplanets discovered so far have been ones about the size of Neptune or smaller. Many of those are rocky “super-Earths” which are smaller than Neptune, but larger than Earth. Others have been about the size of Earth or smaller, while others are gas giants like Jupiter. To date, 3,497 have been confirmed altogether according to the Open Exoplanet Catalogue with another 4,496 candidates and 2,337 confirmed from Kepler alone.
Kepler also discovered the enigmatic dips in brightness of the now-famous star called Boyajian’s Star, which astronomers have been trying to explain for a few years now. It’s weird behaviour of suddenly dimming by up to 22%, as well as more subtle long-term variations in brightness, have produced theories ranging from giant planets with giant ring systems to disintegrating planets or massive comets to alien mega-structures.
The Habitable Exoplanets Catalog currently lists 52 other potentially habitable exoplanets, apart from these new ones. 30 are super-Earth or mini-Neptune size, 21 are Earth-size and 1 is Mars-size. That number will surely continue to grow in the months and years ahead.
The new exoplanet paper is available here.
This article was first published on Futurism.
Exoplanets have been found in all different types and sizes, showing how much diversity there is among planets outside of our own Solar System. Now another one, a “monster exoplanet,” is of interest to astronomers because according to current models of planetary formation, it shouldn’t exist – but does.
The giant planet, called NGTS-1b, is known as a “hot Jupiter,” a gas giant similar to Jupiter but scorching hot due to orbiting close to its star. That’s not so unusual, but what is odd is that the planet orbits a very small red dwarf star. Current understanding of planetary formation says that such a large planet shouldn’t be able to form easily around such small stars.
It should be noted that although this is actually the third hot Jupiter found orbiting a red dwarf star, it is also the largest planet compared to the size of its companion star ever discovered so far, making it a bit more unique. From the new paper:
“NGTS-1b is the third transiting giant planet found around an M-dwarf, reinforcing the notion that close-in gas giants can form and migrate similar to the known population of hot Jupiters around solar type stars.”
NGTS-1b, about 600 light years away, orbits its star in only 2.6 days and its orbit is only 3 percent of the distance between Earth and the Sun.
According to Professor Peter Wheatley from the University of Warwick, “Despite being a monster of a planet, NGTS-1b was difficult to find because its parent star is so small and faint. Small stars like this red M-dwarf are actually the most common in the Universe, so it is possible that there are many of these giant planets waiting to found.”
The planet was discovered by monitoring patches of the night sky over many months, and detecting the red light from the star with innovative red-sensitive cameras.
Hot Jupiters have been found to be quite common in our galaxy, but mostly orbiting larger stars.
As Dr. Daniel Bayliss, lead author of the study and also from the University of Warwick, noted, “The discovery of NGTS-1b was a complete surprise to us – such massive planets were not thought to exist around such small stars – importantly, our challenge now is to find out how common these types of planets are in the Galaxy, and with the new Next-Generation Transit Survey (NGTS) facility we are well-placed to do just that.”
NGTS-1b is also the first exoplanet to be discovered by NGTS.
“Having worked for almost a decade to develop the NGTS telescope array, it is thrilling to see it picking out new and unexpected types of planets,” said Wheatley. “I’m looking forward to seeing what other kinds of exciting new planets we can turn up.”
So far, about 3,500 exoplanets have been found in our galaxy by the Kepler Space Telescope and other observatories. The total number is estimated to be in the billions for our galaxy alone, and some studies have even suggested that there are more planets than stars. Many are hot-Jupiters, but the most common appear to be smaller planets, including “super-Earths” which are rocky planets larger than Earth but smaller then Neptune. That is good news as far as the search for extraterrestrial life is concerned. In the next few years, telescopes will also be better at analyzing the atmospheres of some of these planets, looking for possible biosignature gasses such as oxygen or methane.
The largest exoplanet discovered so far is DENIS-P J082303.1-491201 b, which has a mass 28.5 times that of Jupiter; it is so massive that it may actually be a brown dwarf, a “failed star,” rather than a planet.
The new paper, “NGTS-1b: A hot Jupiter transiting an M-dwarf,” is available here.
This article was first published on Futurism.
Space telescopes and ground-based telescopes have been discovering a wide variety of exoplanets in the last few decades – several thousand have been found so far and the estimated total number is in the billions in our galaxy alone. Now, astronomers have found the first exoplanet with titanium oxide in its atmosphere. The chemical compound is rare on Earth but can be found in the atmosphere of some cooler stars.
The planet, a hot-Jupiter called WASP-19b, was observed with the FORS2 instrument on the Very Large Telescope at the European Southern Observatory (ESO) for over one year. It has a similar mass to Jupiter, but orbits its star in only 19 hours. By analyzing the composition of the planet’s atmosphere, estimated to be 2,000 degrees Celsius, astronomers discovered small amounts of titanium oxide, water and traces of sodium, along with a strongly scattering global haze. The team studied variations in the radius of the planet at different light wavelengths. They then compared those to known atmospheric models, in order to examine different properties of the planet’s atmosphere.
“Detecting such molecules is, however, no simple feat,” said Elyar Sedaghati of ESO. “Not only do we need data of exceptional quality, but we also need to perform a sophisticated analysis. We used an algorithm that explores many millions of spectra spanning a wide range of chemical compositions, temperatures, and cloud or haze properties in order to draw our conclusions.”
As noted by Ryan MacDonald, team member and astronomer at Cambridge University, United Kingdom, “The presence of titanium oxide in the atmosphere of WASP-19b can have substantial effects on the atmospheric temperature structure and circulation.”
“To be able to examine exoplanets at this level of detail is promising and very exciting.” said Nikku Madhusudhan, also from Cambridge University.
Titanium oxide is very rare on Earth, but can be found in the atmospheres of cool stars. On such planets it is thought that it could create thermal inversions, where the temperature is higher in the upper atmosphere and lower further down near the surface. This is of course opposite from what we are familiar with on Earth, although ozone creates a similar effect high up in the stratosphere.
Although this is only the first exoplanet where titanium oxide has been found so far, the results will aid astronomers in the study of other exoplanets, hot-Jupiters in particular. Our own Solar System does not have any similar hot-Jupiter type planets, but they have been discovered orbiting a growing number of other stars. They are gas giant planets, orbiting very close to their stars and are searingly hot, hence the name. Many are also larger than Jupiter. Jupiter and Saturn, the two gas giants in our Solar System, are much farther out and much colder. The ice giants, Uranus and Neptune, are colder still. Since hot-Jupiters now seem to be fairly common, scientists are curious as to why there are none in our Solar System. Figuring this out would also provide more clues as to how our own planetary system formed and evolved.
In the near future, astronomers will also be able to better analyze the atmospheres of smaller rocky exoplanets like Earth, in the search for evidence of alien life. While hot-Jupiters are certainly not life-friendly, the improving ability to study their atmospheres is a big step in that direction.
“This important discovery is the outcome of a refurbishment of the FORS2 instrument that was done exactly for this purpose,” said team member Henri Boffin from ESO. “Since then, FORS2 has become the best instrument to perform this kind of study from the ground.”
The new study has been published in the journal Nature.
This article was first published on Futurism.