These Newly-Discovered Planets are Doomed

An artist’s rendition of what a planetary system similar to TOI-2337b, TOI-4329b, and TOI-2669b might look like, where a hot Jupiter-like exoplanet orbits an evolved, dying star. Image Credit: Karen Teramura/University of Hawai?i Institute for Astronomy

Astronomers have spied three more exoplanets. But the discovery might not last long. Each planet is in a separate solar system, and each orbits perilously close to its star. Even worse, all of the stars are dying.

The results?

Three doomed planets.

Continue reading “These Newly-Discovered Planets are Doomed”

Even Really Massive Stars Seem to Have Planets

This artist’s impression shows a close up of the planet b Centauri b, which orbits a binary system with mass at least six times that of the Sun. This is the most massive and hottest planet-hosting star system found to date. The planet is ten times as massive as Jupiter and orbits the two-star system at 100 times the distance Jupiter orbits the Sun. Image: ESO/L. Calçada

Can planets form around massive, hot stars? Some astronomers think they can’t. According to the evidence, planets around stars exceeding three solar masses should be rare, or maybe even non-existent. But now astronomers have found one.

A team of researchers found a binary star that’s six times the mass of the Sun. And it hosts a planet that’s about ten times more massive than Jupiter.

Continue reading “Even Really Massive Stars Seem to Have Planets”

Exoplanetary System Found With 6 Worlds in Orbital Resonance

This artist’s impression shows the view from the planet in the TOI-178 system found orbiting furthest from the star. New research by Adrien Leleu and his colleagues with several telescopes, including ESO’s Very Large Telescope, has revealed that the system boasts six exoplanets and that all but the one closest to the star are locked in a rare rhythm as they move in their orbits. Image Credit: ESO/L. Calçada/spaceengine.org

200 light-years away from Earth, there’s a K-type main-sequence star named TOI (TESS Object of Interest) 178. When Adrian Leleu, an astrophysicist at the Center for Space and Habitability of the University of Bern, observed it, it appeared to have two planets orbiting it at roughly the same distance. But that turned out to be incorrect. In fact, six exoplanets orbit the smallish star.

And five of those six are locked into an unexpected orbital configuration.

Continue reading “Exoplanetary System Found With 6 Worlds in Orbital Resonance”

Planets Don’t Wait for Their Star to Form First

The young star IRS 63 has baby planets forming around it while the star itself is still forming. Image Credit: Segura-Cox et al, 2020.

It looks like we may have to update our theories on how stars and planets form in new solar systems. A team of astronomers has discovered young planets forming in a solar system that’s only about 500,000 years old. Prior to this discovery, astronomers thought that stars are well into their adult life of fusion before planets formed from left over material in the circumstellar disk.

Now, according to a new study, it looks like planets and stars can form and grow up together.

Continue reading “Planets Don’t Wait for Their Star to Form First”

There Could Be Carbon-Rich Exoplanets Made Of Diamonds

llustration of a carbon-rich planet with diamond and silica as main minerals. Water can convert a carbide planet into a diamond-rich planet. In the interior, the main minerals would be diamond and silica (a layer with crystals in the illustration). The core (dark blue) might be iron-carbon alloy. Credit: Shim/ASU/Vecteezy

Scientists are getting better at understanding exoplanets. We now know that they’re plentiful, and that they can even orbit dead white dwarf stars. Researchers are also getting better at understanding how they form, and what they’re made of.

A new study says that some carbon-rich exoplanets could be made of silica, and even diamonds, under the right circumstances.

Continue reading “There Could Be Carbon-Rich Exoplanets Made Of Diamonds”

Europa’s entire icy shell shifted 70-degrees a few million years ago

Images from NASA's Galileo spacecraft show the intricate detail of Europa's icy surface. Image: NASA/JPL-Caltech

The mysterious world Europa, the ice-covered second moon of Jupiter, sports deep scars that cut across its face. An international team of investigators studied high-resolution maps of that surface to reveal a pattern: something shook Europa sometime within the past few million years, causing the entire shell to shift by 70 degrees.

Continue reading “Europa’s entire icy shell shifted 70-degrees a few million years ago”

Another Collection of Newly Forming Planetary Systems. This Time from the Gemini Planet Imager

This figure shows the dust rings around young stars captured by the Gemini Planet Imager Exoplanet Survey, or GPIES. The rings show a diversity of shapes and sizes, made more extreme by the different projections of the rings on the sky. (UC Berkeley image by Thomas Esposito)

Over the next decade, several very powerful telescopes will come online. Observing time on these ‘scopes will be in high demand, and their range of targets will span a whole host of topics in astronomy, astrophysics, and cosomology.

One of the topics near the top of the list is exoplanets.

But how will astronomers know where to spend their precious exoplanet observing time?

Continue reading “Another Collection of Newly Forming Planetary Systems. This Time from the Gemini Planet Imager”

Planets Form in Just a Few Hundred Thousand Years

Artist's conceptualization of the dusty TYC 8241 2652 system as it might have appeared several years ago when it was emitting large amounts of excess infrared radiation. Credit: Gemini Observatory/AURA artwork by Lynette Cook. https://www.gemini.edu/node/11836

Astronomers like to observe young planets forming in circumstellar debris disks, the rotating rings of material around young stars. But when they measure the amount of material in those disks, they don’t contain enough material to form large planets. That discrepancy has puzzled astronomers.

The answer might come down to timing.

A new study suggests that planets form much quicker than astronomers think.

Continue reading “Planets Form in Just a Few Hundred Thousand Years”

The Orbit of Uranus. How Long is a Year on Uranus?

Uranus as seen by NASA's Voyager 2. Credit: NASA/JPL

Uranus is a most unusual planet. Aside from being the seventh planet of our Solar System and the third gas giant, it is also classified sometimes as an “ice giant” (along with Neptune). This is because of its peculiar chemical composition, where water and other volatiles (i.e. ammonia, methane, and other hydrocarbons) in its atmosphere are compressed to the point where they become solid.

In addition to that, it also has a very long orbital period. Basically, it takes Uranus a little over 84 Earth years to complete a single orbit of the Sun. What this means is that a single year on Uranus lasts almost as long as a century here on Earth. On top of that, because of it axial tilt, the planet also experiences extremes of night and day during the course of a year, and some pretty interesting seasonal changes.

Orbital Period:

Uranus orbits the Sun at an average distance (semi-major axis) of 2.875 billion km (1.786 billion mi), ranging from 2.742 billion km (1.7 mi) at perihelion to 3 billion km (1.86 billion mi) at aphelion. Another way to look at it would be to say that it orbits the Sun at an average distance of 19.2184 AU (over 19 times the distance between the Earth and the Sun), and ranges from 18.33 AU to 20.11 AU.

Images of Uranus taken over a four year period using the Hubble Space Telescope. Credit: NASA/ESA/HST

The difference between its minimum and maximum distance from the Sun is 269.3 million km (167.335 mi) or 1.8 AU, which is the most pronounced of any of the Solar Planets (with the possible exception of Pluto). And with an average orbital speed of 6.8 km/s (4.225 mi/s), Uranus has an orbital period equivalent to 84.0205 Earth years. This means that a single year on Uranus lasts as long as 30,688.5 Earth days.

However, since it takes 17 hours 14 minutes 24 seconds for Uranus to rotate once on its axis (a sidereal day). And because of its immense distance from the Sun, a single solar day on Uranus is about the same. This means that a single year on Uranus lasts 42,718 Uranian solar days. And like Venus, Uranus’ rotates in the direction opposite of its orbit around the Sun (a phenomena known as retrograde rotation).

Axial Tilt:

Another interesting thing about Uranus is the extreme inclination of its axis (97.7°). Whereas all of the Solar Planets are tilted on their axes to some degree, Uranus’s extreme tilt means that the planet’s axis of rotation is approximately parallel with the plane of the Solar System. The reason for this is unknown, but it has been theorized that during the formation of the Solar System, an Earth-sized protoplanet collided with Uranus and tilted it onto its side.

A consequence of this is that when Uranus is nearing its solstice, one pole faces the Sun continuously while the other faces away – leading to a very unusual day-night cycle across the planet. At the poles, one will experience 42 Earth years of day followed by 42 years of night.

This is similar to what is experienced in the Arctic Circle and Antarctica. During the winter season near the poles, a single night will last for more than 24 hours (aka. a “Polar Night”) while during the summer, a single day will last longer than 24 hours (a “Polar Day”, or “Midnight Sun”).

Meanwhile, near the time of the equinoxes, the Sun faces Uranus’ equator and gives it a period of day-night cycles that are similar to those seen on most of the other planets. Uranus reached its most recent equinox on December 7th, 2007. During the Voyager 2 probe’s historic flyby in 1986, Uranus’s south pole was pointed almost directly at the Sun.

Seasonal Change:

Uranus’ long orbital period and extreme axial tilt also lead to some extreme seasonal variations in terms of its weather. Determining the full extent of these changes is difficult because astronomers have yet to observe Uranus for a full Uranian year. However, data obtained from the mid-20th century onward has showed regular changes in terms of brightness, temperature and microwave radiation between the solstices and equinoxes.

These changes are believed to be related to visibility in the atmosphere, where the sunlit hemisphere is thought to experience a local thickening of methane clouds which produce strong hazes. Increases in cloud formation have also been observed, with very bright cloud features being spotted in 1999, 2004, and 2005. Changes in wind speed have also been noted that appeared to be related to seasonal increases in temperature.

Uranus Dark Spot
Close up of Uranus Dark Spot, taken by the Hubble Telescope. Credit: NASA/ESA/HST

Uranus’ “Great Dark Spot” and its smaller dark spot are also thought to be related to seasonal changes. Much like Jupiter’s Great Red Spot, this feature is a giant cloud vortex that is created by winds – which in this case are estimated to reach speeds of up to 900 km/h (560 mph). In 2006, researchers at the Space Science Institute and the University of Wisconsin observed a storm that measured 1,700 by 3,000 kilometers (1,100 miles by 1,900 miles).

Interestingly enough, while Uranus’ polar regions receive more energy on average over the course of a year than the equatorial regions, the equatorial regions have been found to be hotter than the poles. The exact cause of this remains unknown, but is certainly believed to be due to something endogenic.

Yep, Uranus is a pretty weird place! On this planet, a single year lasts almost a century, and the seasons are characterized by extreme versions of Polar Nights and Midnight Suns. And of course, an average year brings all kinds of seasonal changes, complete with extreme winds, massive storms, and thickening methane clouds.

We have written many articles about the length of a year on other planets here at Universe Today. Here’s How Long is a Year on the Other Planets?, How Long is a Year on Mercury?, How Long is a Year on Venus?, How Long is a Year on Earth?, How Long is a Year on Mars?, How Long is a Year on Jupiter?, How Long is a Year on Saturn?, How Long is a Year on Neptune? and How Long is a Year on Pluto?

If you’d like more info on Uranus, check out Hubblesite’s News Releases about Uranus. And here’s a link to the NASA’s Solar System Exploration Guide to Uranus.

We have recorded an episode of Astronomy Cast just about Uranus. You can access it here: Episode 62: Uranus.

Sources:

Weekly Space Hangout – Jan. 29, 2016: Largest Solar System, Future Missions, and Remembering Our Lost Astronauts

Host: Fraser Cain (@fcain)

Guests:
Carolyn Collins Petersen (thespacewriter.com / space.about.com / @spacewriter )
Morgan Rehnberg (cosmicchatter.org / @MorganRehnberg )
Kimberly Cartier (@AstroKimCartier )
Dave Dickinson (www.astroguyz.com / @astroguyz)
Jolene Creighton (fromquarkstoquasars.com / @futurism)
Paul Sutter (pmsutter.com / @PaulMattSutter)

Continue reading “Weekly Space Hangout – Jan. 29, 2016: Largest Solar System, Future Missions, and Remembering Our Lost Astronauts”