APOD and General Astronomy Discussion Forum
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[c][attachment=0]potw1550a[1].jpg[/attachment][/c][hr][/hr]This fetching cloud of gas was imaged by the ESO Faint Object Spectrograph and Camera (EFOSC2) at ESO's La Silla Observatory. It can be found nestled in the busy constellation of Centaurus in the skies of the southern hemisphere. The cloud of gas — named NGC 3699 — is a planetary nebula, It is distinguished by an irregular mottled appearance and a dark rift, which roughly bisects it.
These objects, despite the name, have nothing to do with planets and are created in the final stages of the evolution of stars similar in mass to the Sun. The name "planetary nebula" arises from the time of their discovery by William Herschel, when they appeared in the telescopes of the time as rounded objects similar in looks to the planets.
Towards the end of their lives, stars like the Sun exhaust the supply of hydrogen in their cores, putting a stop to nuclear reactions. This causes the star's core to contract under the force of gravity and heat up, while the cooler outer layers expand tremendously — the surface of the Sun, for example, will likely engulf the orbit of Earth when it reaches this stage in its evolution. Unusually strong stellar winds push the gaseous outer layers of the star out into space, eventually exposing the core of the star, which begins to emit ultraviolet radiation, ionising the expelled gas, causing the nebula's ethereal glow, and producing beautiful and varied sights, such as the one in this image.
[c][attachment=0]potw1550a[1].jpg[/attachment][/c][hr][/hr]This image, taken with the Wide Field Planetary Camera 2 (WFPC2) on board the NASA/ESA Hubble Space Telescope, shows the globular cluster Terzan 1. Lying around 20 000 light-years from us in the constellation of Scorpius (The Scorpion), it is one of about 150 globular clusters belonging to our galaxy, the Milky Way.
Typical globular clusters are collections of around a hundred thousand stars, held together by their mutual gravitational attraction in a spherical shape a few hundred light-years across. It is thought that every galaxy has a population of globular clusters. Some, like the Milky Way, have a few hundred, while giant elliptical galaxies can have several thousand.
They contain some of the oldest stars in a galaxy, hence the reddish colours of the stars in this image — the bright blue ones are foreground stars, not part of the cluster. The ages of the stars in the globular cluster tell us that they were formed during the early stages of galaxy formation! Studying them can also help us to understand how galaxies formed.
Terzan 1, like many globular clusters, is a source of X-rays. It is likely that these X-rays come from binary star systems that contain a dense neutron star and a normal star. The neutron star drags material from the companion star, causing a burst of X-ray emission. The system then enters a quiescent phase in which the neutron star cools, giving off X-ray emission with different characteristics, before enough material from the companion builds up to trigger another outburst.
Seeing this great image makes me want to say, Halo, Halo!starsurfer wrote:Ring Nebula (M57)
http://www.capella-observatory.com/Imag ... 7Field.htm
Copyright: Volker Wendel, Josef Pöpsel, Bernd Koch, Stefan Binnewies and Rainer Sparenberg
You're so funny, for some reason I imagine you wearing a giant sombrero whilst saying that!Ann wrote:Seeing this great image makes me want to say, Halo, Halo!starsurfer wrote:Ring Nebula (M57)
http://www.capella-observatory.com/Imag ... 7Field.htm
Copyright: Volker Wendel, Josef Pöpsel, Bernd Koch, Stefan Binnewies and Rainer Sparenberg
Ann
)[img3="Credit: ESA/Hubble & NASA"]http://cdn.spacetelescope.org/archives/ ... w1551a.jpg[/img3][hr][/hr]The artistic outburst of an extremely young star, in the earliest phase of formation, is captured in this spectacular image from the NASA/ESA Hubble Space Telescope. The colourful wisps, found in the lower left of the image, are painted onto the sky by a young star cocooned in the partially illuminated cloud of obscuring dust seen to the upper right.
Pictured punching through the enshrouding dust is an extremely hot, blue jet of gas released by the young star. As this jet speeds through space, it collides with cooler surrounding material. The result is the colourful object to the lower left, produced as the cooler material is heated by the jet (opo9524a, potw1307a).
This wispy object is known as HH 34 and it is an example of a Herbig–Haro (HH) object. It resides approximately 1400 light-years away near the Orion Nebula, a large star formation region within the Milky Way. HH objects exist for a cosmically brief time — typically thousands of years — with changes seen in observations taken only a few years apart (heic1113).
Although the jet extends the entire length between the infant star and HH34, only a fraction of it appears visible. This part of the jet possesses an intricate structure of knots and ripples, thought to be caused by the different outbursts catching up and ramming into each other over time.
That is lovely, it should hang in an art gallery! I find it amusing the desciption mentions that it is near the Orion Nebula but it is one of many Herbig Haro objects that are part of the NGC 1999 complex. A wider image by Tony Hallas can be seen here.bystander wrote:Infant Star’s Artistic Outburst (HH 34)
ESA Hubble Picture of the Week | 2015 Dec 21[img3="Credit: ESA/Hubble & NASA"]http://cdn.spacetelescope.org/archives/ ... w1551a.jpg[/img3][hr][/hr]The artistic outburst of an extremely young star, in the earliest phase of formation, is captured in this spectacular image from the NASA/ESA Hubble Space Telescope. The colourful wisps, found in the lower left of the image, are painted onto the sky by a young star cocooned in the partially illuminated cloud of obscuring dust seen to the upper right.
Pictured punching through the enshrouding dust is an extremely hot, blue jet of gas released by the young star. As this jet speeds through space, it collides with cooler surrounding material. The result is the colourful object to the lower left, produced as the cooler material is heated by the jet (opo9524a, potw1307a).
This wispy object is known as HH 34 and it is an example of a Herbig–Haro (HH) object. It resides approximately 1400 light-years away near the Orion Nebula, a large star formation region within the Milky Way. HH objects exist for a cosmically brief time — typically thousands of years — with changes seen in observations taken only a few years apart (heic1113).
Although the jet extends the entire length between the infant star and HH34, only a fraction of it appears visible. This part of the jet possesses an intricate structure of knots and ripples, thought to be caused by the different outbursts catching up and ramming into each other over time.
