Category: Astronomy

The Hubble Space Telescope has captured a image of a lenticular galaxy called NGC 1947. A lenticular galaxy is one that is neither a spiral galaxy, like our Milky Way, nor an elliptical galaxy, but somewhere in between the two. It has a large disk in the middle but unlike other spiral galaxies, it does not have spiral arms reaching out from its center.

This galaxy wasn’t always this way, however. At a point in its past, it did have spiral arms. You can see the evidence of these arms in the swirls of dust which still surround it, as the European Space Agency writes: “the faint remnants of the galaxy’s spiral arms can still be made out in the stretched thin threads of dark gas encircling it.”

Another difference between lenticular galaxies like NGC 1947 and other kinds of galaxy is the rate of star formation. Galaxies like the Milky Way continue to form new stars, especially in their spiral arms, as clouds of dust and gas clump together and are eventually bound by gravitational forces. In lenticular galaxies, however, there is very little star formation. These galaxies have used up most of their interstellar matter so there is not enough material for the formation of many new stars.

This means that the average age of stars in NGC 1947 is getting older, and the galaxy is fading over time. To see the galaxy for yourself, you’d need to be located in the southern hemisphere as it is further south than the celestial equator.

Source: Digital Trends

Scientists know that the atmospheres of planets change over time — Mars, for example, is gradually losing its atmosphere as it evaporates into space. The examples we know of suggested this was a one-way process, where an atmosphere developed and then was subsequently lost. But now, researchers using the Hubble Space Telescope have discovered a very odd planet that seems to be re-growing its atmosphere after having lost it in the past. This is the first time such a thing has been observed.

Planet GJ 1132 b is several times the size of Earth, making it a type called a sub-Neptune, and it started out with a thick atmosphere of hydrogen and helium. But, being close to its hot, young star, this atmosphere was quickly lost and the planet was reduced to a core around the size of Earth. So far, so typical.

Where it gets weird is recent observations from Hubble which show the planet has a secondary atmosphere of hydrogen, hydrogen cyanide, methane, and ammonia. Researchers think that hydrogen from the original atmosphere was absorbed by the planet’s mantle, and is now being released once more by volcanic activity. The atmosphere seems to be replenishing itself even as hydrogen continues to be lost into space.

“It’s super exciting because we believe the atmosphere that we see now was regenerated, so it could be a secondary atmosphere,” said study co-author Raissa Estrela of NASA’s Jet Propulsion Laboratory (JPL) in a statement. “We first thought that these highly irradiated planets could be pretty boring because we believed that they lost their atmospheres. But we looked at existing observations of this planet with Hubble and said, ‘Oh no, there is an atmosphere there.’”

Source: Digital Trends