Wednesday, October 27, 2021

What is the Kilonova?

Kilonova occurs in a compact binary system when two neutron stars or a neutron star and a black hole merge. Kilonovae are thought to emit short gamma-ray bursts and strong electromagnetic radiation due to the radioactive decay of heavy r-process nuclei that are produced and ejected fairly isotropically during the merger process.

What is deep learning?

Deep learning is a class of machine learning algorithms that uses multiple layers to progressively extract higher-level features from the raw input. For example, in image processing, lower layers may identify edges, while higher layers may identify the concepts relevant to a human such as digits or letters or faces.

Tuesday, October 26, 2021

This spooky looking asteroid attended the Halloween party six years ago!

On October 31, 2015, asteroid 2015 TB145 transited 486,000 km from the Earth's surface, about 1.27 times the distance that separates the Moon from our planet.

What attracted the attention of the mass media was the appearance of the asteroid, so much so that it earned the name of Halloween Asteroid. In the first radar images, the asteroid seemed to have a skull shape, with two eyes and nasal passages clearly visible. This is an excellent example of pareidolia, the phenomenon according to which the human mind tends to trace causal forms to everyday objects.

What the giant James Webb telescope will see that Hubble can't

The $10 billion instrument, half the size of a 737 airplane and replete with gold-coated mirrors, will orbit 1 million miles from Earth and peer into places humanity hasn't seen before. This includes some of the first stars ever born, the most distant galaxies, and curious planets in the cosmos.

"It's really cool," marveled Chen, an astronomer at the Space Telescope Science Institute, an organization that will run the James Webb Space Telescope, or JWST.

What are the Borromean rings?

Borromean rings are three simple closed curves in three-dimensional space that are topologically linked and cannot be separated from each other, but that break apart into two unknotted and unlinked loops when any one of the three is cut or removed.

Most commonly, these rings are drawn as three circles in the plane, in the pattern of a Venn diagram, alternatingly crossing over and under each other at the points where they cross. Other triples of curves are said to form the Borromean rings as long as they are topologically equivalent to the curves depicted.

Monday, October 25, 2021

G11.2-0.3, a circularly symmetric supernova remnant containing a dense, rotating dead star at its center

When a massive star collapses, the outer layers of the star are destroyed in an extremely energetic explosion. Depending on the mass of the original star, a dense object, such as a neutron star or black hole, can form and fall behind at the center of the explosion. Such a neutron star, known as a "pulsar" when spinning rapidly, can be kicked out by the thermonuclear shock wave created when the star exploded, causing it to race through space at millions of miles per hour.

The Gum nebula

Among the various celestial objects visible from Earth, the Gum Nebula plays a very particular role.

Located about 1500 light years from Earth, the nebula can be described as an immense sphere of gas with a diameter of a thousand light years!

Observed from our planet, the nebula has an apparent diameter greater than 30 degrees: for comparison the apparent diameter of the full Moon is only half a degree!

In the sky ghosts exist, but they are not scary!

Mirach's Ghost is in fact very little scary and due its name solely to its hazy appearance when viewed through a telescope.

Mirach's Ghost is in fact a galaxy (NGC 404) that is almost exactly on the same line of sight of Mirach, the second brightest star in the constellation Andromeda (in the photo NGC 404 is that blue-white spot in the upper left). Observing NGC 404 is made incredibly difficult by the star's presence, as its glow almost entirely obscures the light emitted by the galaxy.