Universe and astronomy

Spiral Galaxy NGC 4622 Spins "Backwards"

Astronomers have found a spiral galaxy that may be spinning to the beat of a different cosmic drummer. To the surprise of astronomers, the galaxy, called NGC 4622, appears to be rotating in the opposite direction to what they expected. Pictures from the NASA/ESA Hubble Space Telescope helped astronomers determine that the galaxy may be spinning clockwise by showing which side of the galaxy is closer to Earth. This Hubble telescope photo of the oddball galaxy is presented by the Hubble Heritage team. The image shows NGC 4622 and its outer pair of winding arms full of new stars [shown in blue].

Credit:    Z. Levay (STScI)

Hubble Serves Up a Holiday Snow Angel

Hubble Space Telescope's high resolution combines with the Subaru Telescope's wide field-of-view to reveal a depiction of star-forming region S106 that is not possible from either telescope alone. The bipolar S106 shows bright gas in two distinct lobes. The faint stars located near the nebulosity are brown dwarf candidates associated with the region of star formation.

This composite image combines optical and near-infrared astronomical data from the Hubble Space Telescope with mid-infrared data from the ground-based Subaru Telescope, located on Mauna Kea in Hawaii. The Hubble data (H-alpha, J, and H) were taken as part of Hubble Heritage observations of S106 in Feburary 2011. The Subaru data (J, H, and K) were obtained in May 1999.


Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), and the Subaru Telescope (National Astronomical Observatory of Japan)

Hubble Spies Cosmic Dust Bunnies

Like dust bunnies that lurk in corners and under beds, surprisingly complex loops and blobs of cosmic dust lie hidden in the giant elliptical galaxy NGC 1316. This image made from data obtained with the NASA Hubble Space Telescope reveals the dust lanes and star clusters of this giant galaxy that give evidence that it was formed from a past merger of two gas-rich galaxies.

The combination of Hubble's superb spatial resolution and the sensitivity of the Advanced Camera for Surveys (ACS), installed onboard Hubble in 2002 and used for these images, enabled uniquely accurate measurements of a class of red star clusters in NGC 1316. Astronomers conclude that these star clusters constitute clear evidence of the occurrence of a major collision of two spiral galaxies that merged together a few billion years ago to shape NGC 1316 as it appears today.

NGC 1316 is on the outskirts of a nearby cluster of galaxies in the southern constellation of Fornax, at a distance of about 75 million light-years. It is one of the brightest ellipticals in the Fornax galaxy cluster. NGC 1316, also known as Fornax A, is one of the strongest and largest radio sources in the sky, with radio lobes extending over several degrees of sky (well off the Hubble image).

NGC 1316's violent history is evident in various ways. Wide-field imagery from Cerro Tololo Interamerican Observatory in Chile shows a bewildering variety of ripples, loops and plumes immersed in the galaxy's outer envelope. Amongst these so-called "tidal" features, the narrow ones are believed to be the stellar remains of other spiral galaxies that merged with NGC 1316 some time during the last few billion years. The inner regions of the galaxy shown in the Hubble image reveal a complicated system of dust lanes and patches. These are thought to be the remains of the interstellar medium associated with one or more of the spiral galaxies swallowed by NGC 1316.

The U.S. team of scientists, led by Dr. Paul Goudfrooij of the Space Telescope Science Institute in Baltimore, Maryland, used the ACS onboard Hubble to study star clusters in several nearby giant elliptical galaxies. Their study of NGC 1316 focused on globular clusters, which are compact stellar systems with hundreds of thousands to millions of stars formed at the same time.

The unprecedented sensitivity of the Hubble ACS data permitted the team to detect faint globular clusters previously impossible to reach. By counting the number of globular clusters detected as a function of their brightness they could, for the first time, see evidence of the gradual disruption of star clusters created during a past merger of gas-rich galaxies. They found that the relative number of low-mass clusters is significantly lower in the inner regions than in the outer regions, by an amount consistent with theoretical predictions.


Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)

Acknowledgment: P. Goudfrooij (STScI)

The Majestic Sombrero Galaxy, M104

NASA's Hubble Space Telescope has trained its razor-sharp eye on one of the universe's most stately and photogenic galaxies, the Sombrero galaxy, Messier 104 (M104). The galaxy's hallmark is a brilliant white, bulbous core encircled by the thick dust lanes comprising the spiral structure of the galaxy. As seen from Earth, the galaxy is tilted nearly edge-on. We view it from just six degrees north of its equatorial plane. This brilliant galaxy was named the Sombrero because of its resemblance to the broad rim and high-topped Mexican hat.

At a relatively bright magnitude of +8, M104 is just beyond the limit of naked-eye visibility and is easily seen through small telescopes. The Sombrero lies at the southern edge of the rich Virgo cluster of galaxies and is one of the most massive objects in that group, equivalent to 800 billion suns. The galaxy is 50,000 light-years across and is located 28 million light-years from Earth.

Hubble easily resolves M104's rich system of globular clusters, estimated to be nearly 2,000 in number — 10 times as many as orbit our Milky Way galaxy. The ages of the clusters are similar to the clusters in the Milky Way, ranging from 10-13 billion years old. Embedded in the bright core of M104 is a smaller disk, which is tilted relative to the large disk. X-ray emission suggests that there is material falling into the compact core, where a 1-billion-solar-mass black hole resides.

In the 19th century, some astronomers speculated that M104 was simply an edge-on disk of luminous gas surrounding a young star, which is prototypical of the genesis of our solar system. But in 1912, astronomer V. M. Slipher discovered that the hat-like object appeared to be rushing away from us at 700 miles per second. This enormous velocity offered some of the earliest clues that the Sombrero was really another galaxy, and that the universe was expanding in all directions.

The Hubble Heritage Team took these observations in May-June 2003 with the space telescope's Advanced Camera for Surveys. Images were taken in three filters (red, green, and blue) to yield a natural-color image. The team took six pictures of the galaxy and then stitched them together to create the final composite image. One of the largest Hubble mosaics ever assembled, this magnificent galaxy has an apparent diameter that is nearly one-fifth the diameter of the full moon.


Credit: NASA and The Hubble Heritage Team (STScI/AURA)

Hubble offers a dazzling necklace

A giant cosmic necklace glows brightly in this NASA/ESA Hubble Space Telescope image.

The object, aptly named the Necklace Nebula, is a recently discovered planetary nebula, the glowing remains of an ordinary, Sun-like star. The nebula consists of a bright ring, measuring about two light-years across, dotted with dense, bright knots of gas that resemble diamonds in a necklace. The knots glow brightly due to absorption of ultraviolet light from the central stars.

A pair of tightly orbiting stars produced the nebula, also called PN G054.2-03.4. About 10 000 years ago one of the aging stars ballooned to the point where it engulfed its companion star. The smaller star continued orbiting inside its larger companion, increasing the giant’s rotation rate, so that the bloated star span so fast that a large part of its gaseous envelope expanded into space. Most of the gas escaped along the star’s equator, producing a ring. The bright knots are dense gas clumps in the ring.

The pair is so close, only a few million kilometres apart, that they appear as one bright dot in the centre of this image. The stars are furiously whirling around each other, completing an orbit in a little more than a day. For comparison, Mercury, the innermost planet of our Solar System, orbits the Sun in 88 days.

The Necklace Nebula is located 15 000 light-years away in the constellation of Sagitta (The Arrow). In this composite image, taken on 2 July, Hubble’s Wide Field Camera 3 captured the glow of hydrogen (blue), oxygen (green), and nitrogen (red).

Credit:

NASA, ESA and the Hubble Heritage Team (STScI/AURA)

Blue Stars Ring Nucleus of Galaxy AM 0644-741

Image Credit:   NASA / Hubble Heritage

The Pencil Nebula

The Pencil Nebula: Remnants of an Exploded Star (NGC 2736)

Image Credit:  NASA / Hubble Heritage

Hubble Sees Galaxy on Edge

NGC 5866 is an edge-on galaxy that is tilted to our line-of-sight. It is classified as an S0 lenticular, due to its flat stellar disk and large ellipsoidal bulge. NGC 5866 lies in the Northern constellation Draco - The Dragon, at a distance of 44 million light-years (13.5 Megaparsecs). It has a diameter of roughly 60,000 light-years (18,400 parsecs). This Hubble image of NGC 5866 is a combination of blue, green and red observations taken with the Hubble Telescope's Advanced Camera for Surveys in November 2005.


Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)

Acknowledgment: W. Keel (University of Alabama, Tuscaloosa)

The Whirlpool Galaxy M51, in Infra Red

This image by NASA's Hubble Space Telescope show a face-on view of the spiral galaxy M51, dubbed the Whirlpool Galaxy.

The image highlights the attributes of a typical spiral galaxy, including graceful, curving arms, pink star-forming regions, and strands of star clusters. Most of the starlight has been removed, revealing the Whirlpool's skeletal dust structure, as seen in near-infrared light. This new image is the sharpest view of the dense dust in M51. The narrow lanes of dust revealed by Hubble reflect the galaxy's moniker, the Whirlpool Galaxy, as if they were swirling toward the galaxy's core.

Image credit  NASA / Hubble

A Cosmic Butterfly

They say the flap of a butterfly's wings can set off a tornado on the other side of the world. But what happens when a butterfly flaps its wings in the depths of space?

This cosmic butterfly is a nebula known as AFGL 4104, or Roberts 22. Caused by a star that is nearing the end of its life and has shrugged off its outer layers, the nebula emerges as a cosmic chrysalis to produce this striking sight. Studies of the lobes of Roberts 22 have shown an amazingly complex structure, with countless intersecting loops and filaments.

A butterfly's life span is counted in weeks; although on a much longer timescale, this stage of life for Roberts 22 is also transient. It is currently a preplanetary nebula, a short-lived phase that begins once a dying star has pushed much of the material in its outer layers into space, and ends once this stellar remnant becomes hot enough to ionise the surrounding gas clouds and make them glow. About 400 years ago, the star at the centre of Roberts 22 shed its outer shells, which raced outwards to form this butterfly. The central star will soon be hot enough to ionise the surrounding gas, and it will evolve into a fully fledged planetary nebula.

Information about the nature, age, and structure of Roberts 22 was presented in a paper using Hubble data back in 1999, published in The Astronomical Journal.

Credit:

NASA, ESA, and R. Sahai (Jet Propulsion Laboratory)