Most of the potentially habitable exoplanets we’ve discovered orbit small red dwarf stars. Red dwarfs make up about 75% of the stars in our galaxy. Only about 7.5% of stars are g-type like our Sun. As we look for life on other worlds, red dwarfs would seem to be their most likely home. But red dwarfs pose a serious problem for habitable worlds.Continue reading “Even older red dwarf stars are pumping out a surprising amount of deadly radiation at their planets”
Welcome back to our Fermi Paradox series, where we take a look at possible resolutions to Enrico Fermi’s famous question, “Where Is Everybody?” Today, we examine the possibility that the reason for the Great Silence is that we are “early to the party”!
In 1950, Italian-American physicist Enrico Fermi sat down to lunch with some of his colleagues at the Los Alamos National Laboratory, where he had worked five years prior as part of the Manhattan Project. According to various accounts, the conversation turned to aliens and the recent spate of UFOs. Into this, Fermi issued a statement that would go down in the annals of history: “Where is everybody?“
This became the basis of the Fermi Paradox, which refers to the disparity between high probability estimates for the existence of extraterrestrial intelligence (ETI) and the apparent lack of evidence. Since Fermi’s time, there have been several proposed resolutions to his question, which includes the Firstborn Hypothesis that states that humanity could be the first intelligent life to emerge in our galaxy.Continue reading “Beyond “Fermi’s Paradox” X: What is the Firstborn Hypothesis?”
In the past decade, the study of exoplanets has grown by leaps and bounds. At present, a total of 4,201 planets have been confirmed beyond the Solar System and another 5,481 candidates await confirmation. In the midst of all this, M-type red dwarf stars have become a focus of exoplanet research because they appear to be the most likely place where rocky (aka. Earth-like) planets can be found orbiting within the star’s habitable zone (HZ).
However, that does not mean that red dwarf stars are good candidates for hosting habitable planets. Take GJ 887, for example, one of the brightest M stars in the sky that has a system of two (possibly three) planets. In the past, this star was believed to be calm and stable, but new research by astronomers from Arizona State University has shown that GJ 887 might not be so calm as previously thought.Continue reading “Astronomers Thought They’d Found a Red Dwarf That Wasn’t Hostile to its Habitable Zone Planets. They Were Wrong”
In 2017, an international team of astronomers announced a momentous discovery. Based on years of observations, they found that the TRAPPIST-1 system (an M-type red dwarf located 40 light-years from Earth) contained no less than seven rocky planets! Equally exciting was the fact that three of these planets were found within the star’s Habitable Zone (HZ), and that the system itself has had 8 billion years to develop the chemistry for life.
At the same time, the fact that these planets orbit tightly around a red dwarf star has given rise to doubts that these three planets could maintain an atmosphere or liquid water for very long. According to new research by an international team of astronomers, it all comes down to the composition of the debris disk that the planets formed from and whether or not comets were around to distribute water afterward.Read more
We tend to think of our Earthly circumstances as normal. A watery, temperate world orbiting a stable yellow star. A place where life has persisted for nearly 4 billion years. It’s almost inevitable that when we think of other places where life could thrive, we use our own experience as a benchmark.
But should we?Continue reading “The Perfect Stars to Search for Life On Their Planets”
NASA’s TESS (Transiting Exoplanet Survey Satellite) has found its first Earth-sized planet located in the habitable zone of its host star. The find was confirmed with the Spitzer Space Telescope. This planet is one of only a few Earth-sized worlds ever found in a habitable zone.Continue reading “TESS Finds its First Earth-Sized World in the Habitable Zone of a Star”
In 2018, scientists announced the discovery of a extrasolar planet orbiting Barnard’s star, an M-type (red dwarf) that is just 6 light years away. Using the Radial Velocity method, the research team responsible for the discovery determined that this exoplanet (Barnard’s Star b) was at least 3.2 times as massive as Earth and experienced average surface temperatures of about -170 °C (-274 °F) – making it both a “Super-Earth” and “ice planet”.
Based on these findings, it was a foregone conclusion that Barnard b would be hostile to life as we know it. But according to new study by a team of researchers from Villanova University and the Institute of Space Studies of Catalonia (IEEC), it is possible – assuming the planet has a hot iron/nickel core and experiences enhanced geothermal activity – that this giant iceball of a planet could actually support life.Continue reading “Geothermal Heating Could Make Life Possible on the Super Earth Planet at Barnard’s Star”
In recent years, the number of extra-solar planets discovered around nearby M-type (red dwarf stars) has grown considerably. In many cases, these confirmed planets have been “Earth-like“, meaning that they are terrestrial (aka. rocky) and comparable in size to Earth. These finds have been especially exciting since red dwarf stars are the most common in the Universe – accounting for 85% of stars in the Milky Way alone.
Unfortunately, numerous studies have been conducted of late that indicate that these planets may not have the necessary conditions to support life. The latest comes from Harvard University, where postdoctoral researcher Manasvi Lingam and Professor Abraham Loeb demonstrate that planets around M-type stars may not get enough radiation from their stars for photosynthesis to occur.Continue reading “Habitable Planets Around Red Dwarf Stars Might not get Enough Photons to Support Plant Life”
New research from the Hubble Space Telescope and the ESO’s Very Large Telescope is dampening some of the enthusiasm in the search for life. Observations by both ‘scopes suggest that the raw materials necessary for life may be rare in solar systems centered around red dwarfs.
And if the raw materials aren’t there, it may mean that many of the exoplanets we’ve found in the habitable zones of other stars just aren’t habitable after-all.Continue reading “Bad News. Planets Orbiting Red Dwarfs Might not have the Raw Materials for Life”
The most common type of star in the galaxy is the red dwarf star. None of these small, dim stars can be seen from Earth with the naked eye, but they can emit flares far more powerful than anything our Sun emits. Two astronomers using the Hubble space telescope saw a red dwarf star give off a powerful type of flare called a superflare. That’s bad news for any planets in these stars’ so-called habitable zones.
Red dwarfs make up about 75% of the stars in the Milky Way, so they probably host many exoplanets. In fact, scientists think most of the planets that are in habitable zones are orbiting red dwarfs. But the more astronomers observe these stars, the more they’re becoming aware of just how chaotic and energetic it can be in their neighbourhoods. That means we might have to re-think what habitable zone means.
“When I realized the sheer amount of light the superflare emitted, I sat looking at my computer screen for quite some time just thinking, ‘Whoa.'” – Parke Loyd, Arizona State University.