Stellar fireworks and tornados

These Cambridge terms absolutely fly by, so here is another astronomical post to mark the start of the holiday and the ushering in of spring at last! I got an exciting physics-themed job offer yesterday and a quick tour of some pretty stars is my idea of a celebration.

Cosmic Tornado and its outflows

Protostar outflow Herbig-Haro 49/50 (L), to be found in the Chameleon nebula star forming region (R). Credit: NASA/ESA/CSA/STScI

The left image snapped by the Webb telescope captures a rare and chance alignment of a nearby protostellar outflow (ejection of gas from a young, forming star) in orange, and a distant spiral galaxy in blue in the background (blob in the top left corner). The jets launched from the young star slam into denser surrounding gas at 100-300 km/s, creating shockwaves and heat. The surrounding material then cools by emitting light at infrared and visible wavelengths for Webb to see. Observations have found dust grains, glowing molecules of hydrogen, and carbon monoxide, shown above in orange and red on the left. The source of this jet is thought to a young protostar a few million years old, the prime age in which stars gain mass from their surrounding whirling gas that feeds the star's growth and eventually flattens into a disc from which planets may form.

The outflow, Herbig-Haro 49/50, is in the Chameleon constellation, home to the stunning star forming nursery in the Chameleon nebula shown on the right. Here, low mass stars like our Sun are forming, and it is likely the Sun formed in a similar environment.

Star formation fireworks

Protostar jet system Lynds 483. Credit: NASA/ESA/CSA/STScI

Another classic hourglass figure (for me the first thing I think of on hearing that phrase is protostar jets rather than ladies modelling on a catwalk, but maybe it's just an astrophysicist thing) this snapshot of star formation in Lynds 483 was snapped by the Webb telescope recently. At the heart of this hourglass will be the core of a young star accreting mass from its surrounding material, slightly obscured by a disc of dust rotating around it. In addition to the wonderful colours, the background stars twinkling like pinpricks add a certain celestial beauty to the spectacle unfolding in the foreground. A similarly beautiful protostar image was mentioned in an earlier post on Webb's images here.

Veil of a supernova remnant

Veil Nebula, supernova remnant. Credit: ESA/Hubble & NASA, R. Sankrit

About 10,000 years ago, a star ~20 times more massive than the Sun exploded, and this magnificent photo shows the remnants of the supernova (explosion) taken by the Hubble telescope. The Veil Nebula features a range of elements including hydrogen, sulphur and oxygen, and the motion of gas filaments has been studied over decades by combining snapshots taken years apart. Massive stars are able to reach higher temperatures than smaller ones, and as such can burn heavier elements, which are then scattered throughout the interstellar medium when the stars eventually explode. These elements (such as oxygen) enrich the surrounding gas from which subsequent generations of stars are made millions of years later, essentially recycling on a cosmic scale. Later generations of stars formed from enriched gas evolve differently to the first generation of stars, which were formed almost purely from hydrogen with smatterings of helium, and were able to reach sizes and temperatures not possible for the later generations of stars that we see in the present day. The Sun is thought to be a 3rd generation star, meaning some of the material in it has already been recycled from two previous stars, similar to a parent and grandparent, but where far less than half of the material is passed on. Stars which are enriched with heavy elements leftover from previous stellar generations evolve somewhat differently to their predecessors, as chemical makeup is one of the key factors influencing how a star will live.

Zooming out into a galaxy

NGC 5048, a spiral galaxy in the Hydra constellation ('water snake’). Credit: ESA/Hubble & NASA, D. Thilker

48 million light years away, this striking galaxy resides in the Hydra constellation, meaning 'water snake' when translated from Greek. The Hubble telescope observed this galaxy (named NGC 5042) in sixth wavelength bands, from ultraviolet to infrared, meaning some of the light captured was beyond the range human eyes can see. As such, this portrait has been artificially constructed with the different colours assigned to different chemical substances observed in the galaxy (for those who are shocked by this revelation, I should point out this is the norm in astronomy and Hubble takes photos in black and white, with the pixel intensity values only later converted into human visible colours by astronomers on computers). Nevertheless, this pretty picture shows ancient stars crammed into the cream coloured centre, and young blue stars in the spiral arms, where there is more fresh gas for stars to form from, and generally more activity. The pink gas clouds studded throughout the arms are H II regions, something I studied on a fascinating internship in Sweden. Their distinctive colours are caused by hydrogen atoms that have been ionised by UV radiation. On closer inspection, it can be seen these pink regions often surround the blue clumps of young stars. This is because only the most massive (usually young) stars reach temperatures high enough to create such a region. However, massive stars have a 'live fast, die young' lifestyle caused by the high rate of chemical reactions in their core required to sustain their huge sizes, and so they only live a few million years, which may sound like a long time, but is a mere blink of an eye on cosmic scale spanning billions of years. As such, these pink regions may not exist in a few million years once their nearby stars have died out, so this photo can be thought of as a fleeting snapshot of a constantly evolving galaxy.