Astronomers observe cloud changes above the northern polar lakes of Titan

Changes seen in Titan's atmosphere
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Using data from both ground- and space-based telescopes, astronomers have now observed clouds rising in the thick atmosphere of the Saturn moon Titan.

The team observed Titan in November 2022 and July 2023 using both Keck Observatory and the James Webb Space Telescope. Those observations not only showed clouds in the mid and high northern latitudes on Titan — the hemisphere where it is currently summer — but also showed those clouds apparently rising to higher altitudes over time. While previous studies have observed cloud convection at southern latitudes, this is the first time evidence for such convection has been seen in the north. This is significant because most of Titan’s lakes and seas are located in its northern hemisphere and evaporation from lakes is a major potential methane source. Their total area is similar to that of the Great Lakes in North America.

The image to the right shows these methane clouds, indicated by the arrows, as seen by Webb on July 11, 2023 and then three days later by Keck. The clouds appear to have shifted downward during these observations.

The data suggests we are seeing one small aspect of Titan’s atmospheric methane cycle, where the liquid methane in the lakes evaporates to form clouds, which later than condense to rain back down. Though superficially similar to the water cycle here on Earth, the details suggest it will be very different on Titan.

Astronomers find galaxy with nine rings

The Bullseye Galaxy
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Using both the Hubble Space Telescope as well as the Keck telescope in Hawaii, astronomers have discovered a galaxy with nine rings, something never seen before.

The gargantuan galaxy LEDA 1313424 is rippling with nine star-filled rings after an “arrow” — a far smaller blue dwarf galaxy — shot through its heart. Astronomers using Hubble identified eight visible rings, more than previously detected by any telescope in any galaxy, and confirmed a ninth using data from the W. M. Keck Observatory in Hawaii. Previous observations of other galaxies show a maximum of two or three rings.

More information from Keck can be found here.

Keck Observatory and Hubble’s follow-up observations helped the researchers prove which galaxy plunged through the center of the Bullseye — a blue dwarf galaxy to its center-left. This relatively tiny interloper traveled like a dart through the core of the Bullseye about 50 million years ago, leaving rings in its wake like ripples in a pond. A thin trail of gas now links the pair, though they are currently separated by 130,000 light-years.

The Hubble picture is to the right, cropped, reduced, and sharpened to post here. The small blue dwarf galaxy to the left is believed to be the galaxy that plowed through LEDA 1313424 to create the rings. LEDA is itself thought to be two and a half times the size of the Milky Way, making one of the larger known galaxies.

Astronomers discover dwarf binary star system invisible to the human eye

Using the infrared instrument on the Keck telescope in Hawaii, astronomers have discovered a dwarf binary star system invisible to the human eye, with the tightest orbit ever seen.

The two stars are so close that it takes them less than one Earth day to revolve around each other; each star’s “year” lasts just 17 hours.

The newly discovered system, named LP 413-53AB, is composed of a pair of ultracool dwarfs, a class of very low-mass stars that are so cool that they emit their light primarily in the infrared, making them completely invisible to the human eye. They are nonetheless one of the most common types of stars in the universe.

Previously, astronomers had only detected three short-period ultracool dwarf binary systems, all of which are relatively young — up to 40 million years old. LP 413-53AB is estimated to be billions of years old — similar in age to our Sun — but has an orbital period that is about four times shorter than all the ultracool dwarf binaries discovered so far.

The two stars’ mutual orbit generally places them only about 600,000 miles apart. For comparison, the Moon orbits the Earth at a distance of 240,000 miles.