Making Planets

ALMA image of the protoplanetary disc around HL TauriThis image from the Atacama Large Millimeter/submillimeter Array at the European Souther Observatory in Chile reveals extraordinarily fine detail that has never been seen before in the planet-forming disc around a young star, in this case, HL Tauri. This is one of the sharpest pictures ever made at submillimetre wavelengths. It’s an enormous step forward in the observation of how protoplanetary discs develop and how planets form.

HL Tauri’s disc appears much more developed than would be expected from the age of the system, suggesting that the planet-formation process may be faster than previously thought. Young stars are born in clouds of gas and fine dust which have collapsed under the effects of gravitation. The dense hot cores eventually ignite to become young stars. These young stars are initially cocooned in the remaining gas and dust, which eventually settles into a protoplanetary disc.

Image Credit: ESO

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

Stellar Explosions in Orion

Stellar explosions are usually associated with supernovae, the spectacular deaths of stars. New ALMA observations of the Orion Nebula provide insights into explosions at the other end of the stellar life cycle, star birth. This image shows the remains of a 500-year-old explosion from the birth of a group of massive stars; star formation can be a violent and explosive process too.

The colors in the ALMA data represent the relative Doppler shifting of the millimetre-wavelength light emitted by carbon monoxide gas. Blue data represents gas approaching at the highest speeds; the red data is from gas moving toward us more slowly.

The millimetre wave data is superimposed over optical and near-infrared images from the Gemini South and the ESO Very Large Telescope. The famous Trapezium Cluster of hot young stars appears towards the bottom of this image. The ALMA data only covers the central portion of the picture.

Image Credit: ESO