Astrophysics

Jun 26 2020

Giant stars prevent the formation of planets

The chance for a young star to raise some planetary offspring apparently depends a great deal on the neighborhood it lives in. This, at least, is one finding that astronomers have discovered with the help of the Hubble Space Telescope. For three years, they observed the open star cluster Westerlund 2 which contains about 5,000 stars, including some real giants, within a relatively small space. Westerlund 2 is only one to two million years old. That makes it an ideal candidate to test theories on planet formation, because all the stars it contains have just started or are just…

What a rare ring galaxy reveals about cosmic history

Astrophysics

Jun 25 2020

What a rare ring galaxy reveals about cosmic history

Ring galaxies like the well-known Cartwheel Galaxy can form for two reasons: First – a spiral galaxy is involved in a collision with another galaxy, which punches through the spiral galaxy, thereby clearing away its center. Second – the bar of a barred spiral galaxy becomes unstable because its rotational velocity becomes too high. Events like these are rare, so ring galaxies themselves are also rare. (more…)

Astrophysics

Jun 24 2020

2019 LD2: the unruly comet

Asteroids and comets are generally thought to be different classes of celestial objects. But is the strict distinction really justified? The interstellar visitor ʻOumuamua, for example, was initially thought to be a comet, but didn’t develop either a coma or a tail and was then classified as an asteroid. In the meantime, its trajectory has been calculated so precisely that it must have lost mass – which means it is definitely a comet. The object 2019 LD2 discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) of the University of Hawaii also appears to be some sort of hybrid.…

Astrophysics

May 13 2020

Life in a hydrogen-rich atmosphere

The exoplanet K2-18b, about 124 light-years from Earth, is a kind of mini-Neptune, as astronomers discovered this past year. It is seven to ten times heavier than Earth and its radius is 2.7 times larger. K2-18b orbits its host star, a red dwarf, once every 33 days. Thus, it is located in its star’s habitable zone. For astronomers, however, it has one other special noteworthy feature: hydrogen, helium, and water vapor have been detected in its atmosphere. In the media, K2-18b has even been described as “Earth 2.0,” which it very definitively is not. The researchers who studied it…

Silent Sun: The phenomenon of our quiet star

Astrophysics

May 11 2020

Silent Sun: The phenomenon of our quiet star

The Sun is rather quiet. That’s the premise of my novel “Silent Sun.” But now researchers at the Max Planck Institute for Solar System Research (MPS) in Göttingen, Germany have also proved it with a systematic comparison published in Science. In such analyses, of course, it is important to make sure you are not comparing apples with oranges. Red dwarfs, for example, are considered much more active. But even among the class of yellow dwarfs like the Sun, there can be big differences. Therefore, the researchers selected candidate stars that were similar to the Sun in terms of important…

Pulsars: of black widows and redback spiders

Astrophysics

May 3 2020

Pulsars: of black widows and redback spiders

Double-star systems end like many marriages: one of the partners almost always dies before the other. When a star dies, if it was not too large, all that remains is a neutron star. This contains a big portion of the mass of the original star, but has a diameter of only about 20 kilometers (12.4 miles). So, like a figure skater who pulls in her arms to spin faster, the neutron star must rotate very quickly about its axis. In doing so, it emits radio waves like a lighthouse – for astronomers it becomes a pulsar, because the radio…

How monster galaxies feed off of their neighbors

Astrophysics

May 2 2020

How monster galaxies feed off of their neighbors

In very large, ancient galaxies, usually more than ten billion light-years away from us, many stars behave differently than in the Milky Way, where the large majority of stars obediently follow the motion of arms rotating about the center of the galaxy. Why is that? It seems galaxies have something in common with people: when there’s too much substance around their mid-sections, it’s usually a result of too much eating. Giant galaxies have swallowed up too many of their neighbors, one after the other, as researchers have now shown in the Astrophysical Journal. (more…)

Blown to dust: the first exoplanet visible in a telescope is no more

Astrophysics

May 1 2020

Blown to dust: the first exoplanet visible in a telescope is no more

In 2008, researchers looking at images from the Hubble Space Telescope found a bright spot moving around the star Fomalhaut located 25 light-years from Earth. At 400 million years old, Fomalhaut is still relatively young. The star, twice as heavy as the Sun and 17 times brighter, is also circled by a dust disk that the researchers identified as a remnant from planetary formation. Fomalhaut b was thus the first exoplanet detected through direct, optical imaging, not just indirectly through star crossings or wobbling patterns of movements by its star. In 2015, the approximately Jupiter-sized planet was even given…