Hubble snaps images of a nebula within a cluster: The unique planetary nebula NGC 2818 is nested inside the open star cluster NGC 2818A. Both the cluster and the nebula reside over 10 000 light-years away, in the southern constellation Pyxis (the Compass). NGC 2818 is one of very few planetary nebulae in our galaxy located within an open cluster. Open clusters, in general, are loosely bound and they disperse over hundreds of millions of years. Stars that form planetary nebulae typically live for billions of years. Hence, it is rare that an open cluster survives long enough for one of its members to form a planetary nebula. This open cluster is particularly ancient, estimated to be nearly one billion years old. The spectacular structure of NGC 2818 (also known as PLN 261+8.1) contains the outer layers of a sun-like star that were sent off into interstellar space during the star' s final stages of life. These glowing gaseous shrouds were shed by the star after it ran out of fuel to sustain the nuclear reactions in its core. Planetary nebulae can have extremely varied structures. NGC 2818 has a complex shape that is difficult to interpret. However, because of its location within the cluster, astronomers have access to information about the nebula, such as its age and distance, that might not otherwise be known. Planetary nebulae fade away gradually over tens of thousands of years. The hot, remnant stellar core of NGC 2818 will eventually cool off for billions of years as a white dwarf. Our own Sun will undergo a similar process, but not for another 5 billion years or so. This Hubble image was taken in November 2008 with the Wide Field Planetary Camera 2. The colours in the image represent a range of emissions coming from the clouds of the nebula: red represents nitrogen, green represents hydrogen, and blue represents oxygen.

Name: NGC 2818, NGC 2818a
Type: Milky Way : Star : Grouping : Cluster : OpenMilky Way : Nebula : Type : Planetary
Category: Nebulae
Constellation: Pyxis
Distance: 7500 light years
Release date: 16 January 2009, 16:00
Credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA)

Hubble celebrates the International Year of Astronomy 2009 with the galaxy triplet Arp 274: In celebration of the International Year of Astronomy 2009, the NASA/ESA Hubble Space Telescope photographed the winning target in the Space Telescope Science Institute's "You Decide" competition. The image of the winner, a group of interacting galaxies called Arp 274, was revealed during ESO's "Around the World in 80 Telescopes" webcast. The striking object received 67,021 votes out of the nearly 140,000 votes cast for the six candidate targets. On 1-2 April Hubble's Wide Field Planetary Camera 2 captured Arp 274 (also known as NGC 5679). Arp 274 is a system of three galaxies that appear to be partially overlapping in the image, although they may be at somewhat different distances. The spiral shapes of two of these galaxies appear mostly intact. The third galaxy (far left) is more compact, but shows evidence of star formation. Two of the three galaxies are forming new stars at a high rate. This is evident in the bright blue knots of star formation that are strung along the arms of the galaxy on the right and along the small galaxy on the left. The largest component is located in the middle of the three. It appears as a spiral galaxy, which may be barred. The entire system resides at about 400 million light-years away from Earth in the constellation Virgo. Hubble's Wide Field Planetary Camera 2 was used to image Arp 274. Blue, yellow and infrared filters were combined with a filter that isolates hydrogen emission. The colours in this image reflect the intrinsic colour of the different stellar populations that make up the galaxies. Yellowish older stars can be seen in the central bulge of each galaxy. A bright central cluster of stars pinpoint each nucleus. Younger blue stars trace the spiral arms, along with pinkish nebulae that are illuminated by new star formation. Interstellar dust is silhouetted against the starry population. The pair of foreground stars on the right are inside our own Milky Way. The International Year of Astronomy 2009 is the celebration of the 400th anniversary of Galileo's first observations with a telescope. People around the world are coming together to participate in the IYA's 100 Hours of Astronomy, 2 April to 5 April. This global astronomy event is geared toward encouraging as many people as possible to experience the night sky. Credit: NASA, ESA and M. Livio and the Hubble Heritage Team (STScI/AURA) STScI is an International Year of Astronomy 2009 programme partner. The IYA2009 secretariat is located at ESO headquarters in Garching, Germany.

Name: Arp 274, NGC 5679
Type: Local Universe : Galaxy : Type : Interacting
Category: AnniversaryGalaxies
Constellation: Virgo
Release date: 3 April 2009, 19:00
Credit: NASA & ESA

Bubbles and baby stars: This image is a screen shot from Hubblecast 37 featuring a spectacular new NASA/ESA Hubble Space Telescope image — one of the largest ever released of a star-forming region. It highlights N11, part of a complex network of gas clouds and star clusters within our neighbouring galaxy, the Large Magellanic Cloud. This region of energetic star formation is one of the most active in the nearby Universe. Read more about it in the press release heic1011.

Name: LHA 120-N 11, N11
Type: Local Universe : Nebula : Type : Star Formation
Category: Nebulae
Constellation: Dorado
Distance: 170000 light years
Release date: 22 June 2010, 11:00
Credit: NASA, ESA and Jesús Maíz Apellániz (Instituto de Astrofísica de Andalucía, Spain)

Hubble pinpoints source of mysterious outburst: The NASA/ESA Hubble Space Telescope has pinpointed the source of one of the most puzzling blast of high-energy radiation ever observed. It is at the very center of a small, distant galaxy. The galaxy appears as a bright blob at the centre of the Hubble picture. Astronomers say it is likely that a supermassive black hole at the core of the galaxy has gravitationally torn apart and swallowed a bypassing star. As the star’s gas falls onto the black hole, X-ray and gamma radiation is ejected along a narrow beam towards Earth. If confirmed, this would be the first time this phenomenon has been observed.

Name: GRB 110328A
Type: Early Universe : Cosmology : Phenomenon : Gamma Ray Burst
Category: Cosmology
Constellation: Draco
Distance: 4 billion light years
Release date: 7 April 2011, 15:00
Credit: NASA, ESA and A. Fruchter (STScI)

Hubble’s cepheid in the Andromeda Galaxy: The Hubble Space Telescope has imaged the star field around the Cepheid variable V1 in M31. This image shows individually resolved stars in the outer disk of the Andromeda Galaxy. The soft, brown swirls are dust lanes are obscuring light from stars farther away from our line of sight. The blue cluster towards the upper right of the image contains massive young stars that are emitting intense ultraviolet light. The Cepheid variable, V1, the first Cepheid ever found outside of our own galaxy, is a moderate looking star in the lower left of the image.

Name: Hubble's Cepheid, V1
Type: Local Universe : Star : Type : Variable
Category: Stars
Constellation: Andromeda
Distance: 2 million light years
Release date: 23 May 2011, 20:00
Credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA)