Red Dwarf Stars Archives

November 18, 2023November 18, 2023 by Matt Williams

Under Some Conditions, Comets Could Deliver Organic Molecules to Planets

This artwork shows a rocky planet being bombarded by comets. Image credit: NASA/JPL-Caltech

Approximately 4.1 to 3.8 billion years ago, the planets of the inner Solar System experienced many impacts from comets and asteroids that originated in the outer Solar System. This is known as the Late Heavy Bombardment (LHB) period when (according to theory) the migration of the giant planets kicked asteroids and comets out of their regular orbits, sending them hurtling towards Mercury, Venus, Earth, and Mars. This bombardment is believed to have distributed water to the inner Solar System and maybe the building blocks of life itself.

According to new research from the University of Cambridge, comets must travel slowly – below 15 km/s (9.32 mi/s) – to deliver organic material onto other planets. Otherwise, the essential molecules would not survive the high speed and temperatures generated by atmospheric entry and impact. As the researchers found, such comets are only likely to occur in tightly bound systems where planets orbit closely to each other. Their results show that these systems would be a good place to look for evidence of life (biosignatures) beyond the Solar System.

May 31, 2023May 31, 2023 by Laurence Tognetti

A Third of Planets Orbiting Red Dwarf Stars Could be in the Habitable Zone

A recent study published in the Proceedings of the National Academy of Sciences, a pair of researchers from the University of Florida (UF) examine orbital eccentricities for exoplanets orbiting red dwarf (M dwarf) stars and determined that one-third of them—which encompass hundreds of millions throughout the Milky Way—could exist within their star’s habitable zone (HZ), which is that approximate distance from their star where liquid water can exist on the surface. The researchers determined the remaining two-thirds of exoplanets orbiting red dwarfs are too hot for liquid water to exist on their surfaces due to tidal extremes, resulting in a sterilization of the planetary surface.

March 14, 2023March 14, 2023 by Evan Gough

Even the Calmest Red Dwarfs are Wilder than the Sun

An artist's conception of a violent flare erupting from the red dwarf star Proxima Centauri. Such flares can obliterate atmospheres of nearby planets. Credit: NRAO/S. Dagnello.

There’s something menacing about red dwarfs. Human eyes are accustomed to our benevolent yellow Sun and the warm light it shines on our glorious, life-covered planet. But red dwarfs can seem moody, ill-tempered, and even foreboding.

For long periods of time, they can be calm, but then they can flare violently, flashing a warning to any life that might be gaining a foothold on a nearby planet.

February 28, 2023March 1, 2023 by Matt Williams

Do Red Dwarfs Provide Enough Sunlight for Plants to Grow?

This artist’s impression shows the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image between the planet and Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface. Credit: ESO/M. Kornmesser

To date, 5,250 extrasolar planets have been confirmed in 3,921 systems, with another 9,208 candidates awaiting confirmation. Of these, 195 planets have been identified as “terrestrial” (or “Earth-like“), meaning that they are similar in size, mass, and composition to Earth. Interestingly, many of these planets have been found orbiting within the circumsolar habitable zones (aka. “Goldilocks zone”) of M-type red dwarf stars. Examples include the closest exoplanet to the Solar System (Proxima b) and the seven-planet system of TRAPPIST-1.

These discoveries have further fueled the debate of whether or not these planets could be “potentially-habitable,” with arguments emphasizing everything from tidal locking, flare activity, the presence of water, too much water (i.e., “water worlds“), and more. In a new study from the University of Padua, a team of astrobiologists simulated how photosynthetic organisms (cyanobacteria) would fare on a planet orbiting a red dwarf. Their results experimentally demonstrated that oxygen photosynthesis could occur under red suns, which is good news for those looking for life beyond Earth!

February 25, 2023February 25, 2023 by Matt Williams

59 New Planets Discovered in Our Neighborhood

An artist’s concept of a high-resolution image of an Earth-size planet in the cool range of the habitable zone of a nearby M dwarf. © José A. Caballero (CAB, CSIC-INTA), Javier Bollaín (Render Area)

The hunt for habitable extrasolar planets continues! Thanks to dedicated missions like Kepler, TESS, and Hubble, the number of confirmed extrasolar planets has exploded in the past fifteen years (with 5,272 confirmed and counting!). At the same time, next-generation telescopes, spectrometers, and advanced imaging techniques are allowing astronomers to study exoplanet atmospheres more closely. In short, the field is shifting from the process of discovery to characterization, allowing astronomers to more tightly constraint habitability.

Finding potentially-habitable “Earth-like” planets around these fainter stars is the purpose of the Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Echelle Spectrographs (CARMENES), located at the Calar Alto Observatory in Spain. In a study that appeared in Astronomy & Astrophysics today, the CARMENES Consortium published data (Data Release 1) data from about 20,000 observations taken between 2016 and 2020. Among the measurements obtained from 362 nearby cool stars, the DR1 contained data on 59 new planets.

February 6, 2023February 6, 2023 by Evan Gough

Earth-Sized Planet Found At One of the Lightest Red Dwarfs

Artist’s conception of a rocky Earth-mass exoplanet like Wolf 1069 b orbiting a red dwarf star. If the planet has retained its atmosphere, chances are high that it would feature liquid water and habitable conditions over a wide area of its dayside. Image Credit: NASA/Ames Research Center/Daniel Rutter

Astronomers have found another Earth-sized planet. It’s about 31 light-years away and orbits in the habitable zone of a red dwarf star. It’s probably tidally locked, which can be a problem around red dwarf stars. But the team that found it is optimistic about its potential habitability.

December 14, 2022December 14, 2022 by Evan Gough

Could Life Survive on Frigid Exo-Earths? Maybe Under Ice Sheets

This artist's illustration shows what an icy exo-Earth might look like. A new study says liquid water could persist under ice sheets on planets outside of their habitable zones. Image Credit: NASA

Our understanding of habitability relies entirely on the availability of liquid water. All life on Earth needs it, and there’s every indication that life elsewhere needs it, too.

Can planets with frozen surfaces somehow have enough water to sustain life?

October 29, 2022October 30, 2022 by Laurence Tognetti

Another Reason Red Dwarfs Might Be Bad for Life: No Asteroid Belts

In a recent study accepted to The Astrophysical Journal Letters, a team of researchers at the University of Nevada, Las Vegas (UNLV) investigated the potential for life on exoplanets orbiting M-dwarf stars, also known as red dwarfs, which are both smaller and cooler than our own Sun and is currently open for debate for their potential for life on their orbiting planetary bodies. The study examines how a lack of an asteroid belt might indicate a less likelihood for life on terrestrial worlds.

October 1, 2022October 1, 2022 by Andy Tomaswick

Earthlike Worlds With Oceans and Continents Could be Orbiting red Dwarfs, Detectable by James Webb

“Go then, there are other worlds than these.” Or so Stephen King said in his famous Dark Tower series. As of yet, none of those worlds are known to be like Earth. But, according to some new simulations by researchers at the National Astronomical Observatory of Japan (NAOJ), finding a genuinely Earth-like world might be in the cards by the decade’s end.

August 31, 2022August 31, 2022 by Nancy Atkinson

A Planet has Been Found That Shifts In and Out of the Habitable Zone

Schematic diagram of the newly discovered Ross 508 planetary system. The green region represents the habitable zone where liquid water can exist on the planetary surface. The planetary orbit is shown as a blue line. Credit: Astrobiology Center.

A super-Earth planet has been found orbiting a red dwarf star, only 37 light-years from the Earth. Named Ross 508 b, the newly found world has an unusual elliptical orbit that causes it to shift in and out of the habitable zone. Therefore, part of the time conditions would be conducive for liquid water to exist on the planet’s surface, but other times it wouldn’t.