Main sequence stars such as the Sun wind up as red giants. Studying red giant stars tells astronomers about the future of the Sun (in a few billion years). It also tells us about how previous generations of stars spread the elements needed for life across the Universe. One of the most famous red giants in the sky is called Mira A, part of the binary system Mira about 400 light-years from Earth.
Mira A is an old star, already spewing out the products of its life’s work into space for recycling. Mira B, Mira A’s companion, orbits A at twice the distance from the Sun to Neptune.
Mira A is known to have a slow stellar wind which gently moulds the surrounding material. Mira B is a hot, dense white dwarf with a fierce and fast stellar wind. Recent observations at millimeter wavelengths show how the interaction of the stellar winds from the two stars have created a complex nebula. The bubble at the centre is created by Mira B’s energetic wind inside Mira A’s more relaxed outflow. The heart-shaped bubble, formed some time in the last 400 years or so, is a relatively young object in astronomical terms.
Image Credit: ESO / S. Ramstedt (Uppsala University, Sweden) & W. Vlemmings (Chalmers University of Technology, Sweden)
This picture was assembled from combined observations from NASA’s Spitzer Space Telescope and ESO’s Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. It reveals the throes of stellar birth in an object known as HH 46/47.
HH or Herbig-Haro objects form when particle jets shot out by newborn stars collide with surrounding matter, producing small, bright, nebulous regions. The dynamics within many HH objects are obscured from observation with visible light by the enveloping gas and dust, but the infrared and submillimeter light seen by Spitzer and ALMA, respectively, cuts through the cloud around HH 46/47. (Infrared light has longer wavelengths than what we see with our eyes, and submillimeter wavelengths are longer still.)
In this false-color image the shorter-wavelength light appears blue and longer-wavelength light, red. Blue shows gas energized by the outflowing jets. Green traces a combination of hydrogen gas molecules and dust that follows the boundary of the gas cloud surrounding the young star. The red areas are excited carbon monoxide gas.
Image Credit: NASA / ESO
This image resembles red ink filtering through water or a crackling stream of electricity, but it is actually a view of our cosmic home. It’s the central plane of the Milky Way as seen by ESA’s Planck satellite and the Atacama Pathfinder Experiment (APEX) operated at an altitude of around 5100m in the Chilean Andes by the European Southern Observatory. While APEX is best at viewing small patches of sky in great detail, Planck data is ideal for studying areas of sky at the largest scales. The two data sets complement each other and offer a unique perspective on the sky.
The bright pockets scattered along the galactic plane this view are compact sources of submillimetre radiation: very cold, clumpy, dusty regions that may are being studied for information on multiple questions ranging from how individual stars form to how the entire Universe is structured. From right to left, notable sources include NGC 6334 (the rightmost bright patch), NGC 6357 (just to the left of NGC 6334), the galactic core itself (the central, most extended, and brightest patch in this image), M8 (the bright lane branching from the plane to the bottom left), and M20 (visible to the upper left of M8).
Image Credit: ESA / ESO