Astronomers Thought They’d Found a Red Dwarf That Wasn’t Hostile to its Habitable Zone Planets. They Were Wrong

Artistic design of the super-Earth GJ 625 b and its star, GJ625 (Gliese 625). Credit: Gabriel Pérez/SMM (IAC)

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.

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There’s No Chemical Difference Between Stars With or Without Planets

Orion Nebula - Closest Star Forming Region to Earth c Cimone - Trottier Observatory

Strange New Worlds

Imagine if a star could tell you it had planets. That would be really helpful because finding planets orbiting distant stars – exoplanets – is hard. We found Neptune, the most distant planet in our own solar system, in 1846. But we didn’t have direct evidence of a planet around ANOTHER star until….1995.…149 years later. Think about that. Any science fiction you watched or read that was written before 1995 which depicted travel to exoplanets assumed that other planets even existed. Star Trek: The Next Generation aired its last season in 1994. We didn’t even know if Vulcan was out there. (Now we do!…sortof)

Jupiter (right bright point) and Saturn (left bright point) seen here against the Milky Way were the most distant planets we could see before inventing telescopes – C. Matthew Cimone
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Saturn-sized Planet Found in the Habitable Zone of Another Star. The First Planet Completely Discovered by Amateur Astronomers

Exoplanets have been a particularly hot topic of late.  More than 4000 of them have been discovered since the first in 1995.  Now one more can potentially be added to the list. This one is orbiting Gliese 3470, a red dwarf star located in the constellation Cancer.  What makes this discovery particularly interesting is that this planet wasn’t discovered by any professional astronomers using high tech equipment like the Kepler Space Telescope.  It was found entirely by amateurs.

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Wow! An Actual Picture of Multiple Planets Orbiting a Sunlike Star

This image, captured by the SPHERE instrument on ESO’s Very Large Telescope, shows the star TYC 8998-760-1 accompanied by two giant exoplanets. This is the first time astronomers have directly observed more than one planet orbiting a star similar to the Sun. The image was captured by blocking the light from the young, Sun-like star (on the top left corner) using a coronagraph, which allows for the fainter planets to be detected. The bright and dark rings we see on the star’s image are optical artefacts. The two planets are visible as two bright dots in the centre and bottom right of the frame. Image Credit: ESO/Bohn et al, 2020

We’ve detected thousands of exoplanets, but for the most part, nobody’s ever seen them. They’re really just data, and graphs of light curves. The exoplanet images you see here at Universe Today and other space websites are the creations of very skilled illustrators, equal parts data and creative license. But that’s starting to change.

The European Southern Observatory’s Very Large Telescope (VLT) has captured images of two exoplanets orbiting a young, Sun-like star.

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Astronomers are Starting to Find Planets in Much Longer Orbits. Cooler, More Habitable Planets

This artist’s view shows the planet orbiting the young star Beta Pictoris. This exoplanet is the first to have its rotation rate measured. Its eight-hour day corresponds to an equatorial rotation speed of 100 000 kilometres/hour — much faster than any planet in the Solar System.

We’re getting better and better at detecting exoplanets. Using the transit method of detection, the Kepler Space Telescope examined over 530,000 stars and discovered over 2,600 explanets in nine years. TESS, the successor to Kepler, is still active, and has so far identified over 1800 candidate exoplanets, with 46 confirmed.

But what if, hidden in all that data, there were even more planets? Astronomers at Warwick University said they’ve found one of these “lost” planets, and that they think they’ll find even more.

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A Neptune-class exoplanet has been found with its atmosphere stripped away

Voyager 2 captured this image of Neptune in 1982, when it was over 7 million km (4.4 million miles) away from the planet. The Great Dark Spot in the middle of the image was the first storm ever seen on Neptune. Image: By NASA (JPL image) [Public domain], via Wikimedia Commons

What happens when a giant planet gets stripped of its atmosphere? It leaves behind a giant core, rich in iron and other metals. A team using NASA’s TESS mission recently found such a remnant core, orbiting a star just 730 light-years away.

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Do the TRAPPIST-1 Planets Have Atmospheres?

Most exoplanets orbit red dwarf stars because they're the most plentiful stars. This is an artist's illustration of what the TRAPPIST-1 system might look like from a vantage point near planet TRAPPIST-1f (at right). Credits: NASA/JPL-Caltech
Most exoplanets orbit red dwarf stars because they're the most plentiful stars. This is an artist's illustration of what the TRAPPIST-1 system might look like from a vantage point near planet TRAPPIST-1f (at right). Credits: NASA/JPL-Caltech

In February of 2017, the scientific community rejoiced as NASA announced that a nearby star (TRAPPIST-1) had a system of no less than seven rocky planets! Since that time, astronomers have conducted all kinds of follow-up observations and studies in the hopes of learning more about these exoplanets. In particular, they have been attempting to learn if any of the planets located in the stars Habitable Zone (HZ) could actually be habitable.

Many of these studies have been concerned with whether or not the TRAPPIST-1 planets have sufficient water on their surfaces. But just as important is the question of whether or not any have viable atmospheres. In a recent study that provides an overview of all observations to date on TRAPPIST-1 planets, a team found that depending on the planet in question, they are likely to have good atmospheres, if any at all.

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Do Hot Jupiters Form Close in, or Do They Migrate? A Newly-Discovered Planet Might Help Answer This

Credit: NASA/JPL

The discovery of over 4000 planets (4,171 confirmed and counting!) beyond our Solar System has revolutionized the field of astronomy. Unfortunately, one of the downsides of all these discoveries is how it has shaken up theories about how our Solar System formed. In the past, astronomers thought that the eight planets (or nine, or over one hundred, depending on your point of view) formed where they are currently located.

However, the discovery of gas giants that orbit close to their stars (aka. “Hot Jupiters”) has confounded this thinking. But according to a recent NASA-supported study, the recent discovery of a young gas giant could offer clues as to how Jupiter-like planets form and whether or not they migrate. This discovery was made possible thanks to the Spitzer Space Telescope, which continues to reveal things about our Universe even in retirement.

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Deep Down in Ocean Worlds, it’s Difficult to Tell Where the Oceans End and the Rock Begins

This artist’s concept shows a hypothetical planet covered in water around the binary star system of Kepler-35A and B. The composition of such water worlds has fascinated astronomers and astrophysicists for years. (Image by NASA/JPL-Caltech.)

We all know what water is. And what rock is. The difference is crystal clear. Well, here on Earth it is.

But on other worlds? The difference might not be so clear.

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