Acquisitions and Mergers

This video starts with data from a survey of galaxies (blue and green) done by ESA’s Herschel Space Observatory and zooms in on a source that astronomers found interesting. The zooming in continues using observations performed with the Atacama Pathfinder Experiment (APEX; red). Finally, the video shows further observations obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) at higher resolution. Those observations revealed that the interesting source isn’t an ancient, massive galaxy, but of a pair of distinct massive galaxies about to merge. These two galaxies, each roughly as massive as our Milky Way, were informally dubbed the ‘Horse’ and the ‘Dragon’.

Video Credit: ESA

V838 Monocerotis

V838 Monocerotis (V838 Mon) is a red variable star in the constellation Monoceros about 20,000 light years from the Earth. It was first observed in early 2002 experiencing a major outburst, and it was one of the largest known stars for a short period following the outburst. At first, V838 Mon was thought to be a typical nova eruption, but it is now known to be something completely different. Just what is still uncertain, but a couple of the possibilities are an eruption related to stellar death processes or a merger of a binary star or planets.

The remnant is evolving rapidly. This animation is a morphing sequence between the five individual Hubble images that were taken between 20 May, 2002, and 8 February, 2004.

Video Credit: ESA

Hubble’s Variable Nebula

NGC 2261 is an odd nebula is named for Edwin Hubble, who studied it early last century. It’s appearance can change over short periods of time. Hubble’s Variable Nebula is a reflection nebula made of gas and fine dust moving out from the star R Monocerotis. The faint nebula is about one light-year across and lies about 2500 light-years away in the constellation of Monocerotis (the Unicorn). The leading explanation for the nebula’s rapid changes suggests that dense knots of opaque dust is passing close to R Mon and cast moving shadows onto the reflecting dust seen in the rest of the nebula.

Image Credit: NASA / ESA
Data: Mark Clampin (GSFC)
Processing & License: Judy Schmidt, CC BY 2.0

Messier 5

Messier 5 (aka M5) is a globular star cluster of over 100,000 stars bound by gravity and packed into a region about 165 light-years across. It’s about 25,000 light-years away. Globular star clusters are ancient members of the Milky Way, and M5 is one of the oldest. Its stars are nearly 13 billion years old.

Image Credit: NASA / ESA

Galactic Thinness

ngc 4762This is a disk galaxy seen almost perfectly edge on. The image from the Hubble Space Telescope shows us just how thin disk galaxies can be. NGC 4762, a galaxy in the nearby Virgo Cluster of Galaxies, is so thin that it is actually difficult to determine what type of disk galaxy it is. Its lack of a visible dust lane suggests that it is probably a low-dust lenticular galaxy, but it is still possible that a view from another angle would reveal spiral structure. The galaxy spans about 100,000 light years from end to end, with its center showing a slight bulge of stars. Most galaxies don’t appear this thin because our point of view from Earth doesn’t line up well enough with the planes of their thin galactic disks. However, galaxies this thin are common. Indeed, our own Milky Way Galaxy is thought to have roughly the same overall dimensions as NGC 4762.

Image Credit: NASA / ESA

Asteroid Photobombing

This Hubble image of a random patch of sky is part of a survey called Frontier Fields and was assembled from multiple exposures. It contains thousands of distant galaxies and the trails of asteroids moving through the field of view. The asteroid trails appear as curved or streaks. The combined image show 20 sighting of 7 different asteroids.

Image Credit: NASA / ESA / STScI