Category: Hubble

Back in 1006 A.D, observers from Africa to Europe to the Far East witnessed and recorded the arrival of light from what is now called SN 1006, a tremendous supernova explosion caused by the final death throes of a white dwarf star nearly 7,000 light-years away. One Egyptian astronomer recorded the object was 2 – 3 times as large as the disc of Venus and about one quarter the brightness of the moon. The supernova was probably the brightest star ever seen by humans, visible even during the day for weeks, and it remained visible to the naked eye for at least two and a half years before fading away. Remnants of this supernova are still visible to telescopes, and the Hubble Space Telescope captured this close-up a filament of the shock wave of the explosion, still reverberating through space, seen here against the grid of background stars. The full image of SN 1006 is pretty impressive, too…

SN 1006 has a diameter of nearly 60 light-years, and it is still expanding at roughly 6 million miles per hour. Even at this tremendous speed, however, it takes observations typically separated by years to see significant outward motion of the shock wave against the grid of background stars. In the Hubble image shown here, the supernova would have occurred far off the lower right corner of the image, and the motion would be toward the upper left.

It wasn’t until the mid-1960s that radio astronomers first detected a nearly circular ring of material at the recorded position of the supernova. The ring was almost 30 arcminutes across, the same angular diameter as the full moon. The size of the remnant implied that the blast wave from the supernova had expanded at nearly 20 million miles per hour over the nearly 1,000 years since the explosion occurred.

In 1976, the first detection of exceedingly faint optical emission of the supernova remnant was reported, but only for a filament located on the northwest edge of the radio ring. A tiny portion of this filament is revealed in detail by the Hubble observation. The twisting ribbon of light seen by Hubble corresponds to locations where the expanding blast wave from the supernova is now sweeping into very tenuous surrounding gas.

The hydrogen gas heated by this fast shock wave emits radiation in visible light. Hence, the optical emission provides astronomers with a detailed “snapshot” of the actual position and geometry of the shock front at any given time. Bright edges within the ribbon correspond to places where the shock wave is seen exactly edge on to our line of sight.

Original News Source: HubbleSite

The Coma Cluster is one of the densest known clusters of galaxies, containing thousands of elliptical and spherical star systems. The entire cluster is huge, more than 20 million light-years in diameter. It’s also very far away, over 300 million light years distant. But no telescope brings the Coma Cluster closer than the Hubble Space Telescope, and a new Hubble image has captured the magnificent starry population in one area of the Coma Cluster with the Advanced Camera for Surveys.

The above Hubble image focuses on an area that is roughly one-third of the way out from the center of the whole cluster. One bright spiral galaxy is visible in the upper left of the image (see below for a close-up of this galaxy). It is distinctly brighter and bluer than the galaxies surrounding it. A series of dusty spiral arms appears reddish brown against the whiter disc of the galaxy, and suggests that this galaxy has been disturbed at some point in the past. The other galaxies in the image are either elliptical galaxies, S0 (s-zero) galaxies or background galaxies that are far beyond the Coma Cluster sphere.

Ellipticals are featureless “fuzz-balls,” pale golden brown in color and contain populations of old stars. Both dwarf and giant ellipticals are found in abundance in the Coma Cluster.

Farther out from the centre of the cluster there are several spiral galaxies. These galaxies contain clouds of cold gas that are giving birth to new stars. Spiral arms and dust lanes “accessorise” these bright bluish-white galaxies, which have a distinctive disc structure.

S0 (S-zero) galaxies form a morphological class of objects between the better known elliptical and spiral galaxies. They consist of older stars and show little evidence of recent star formation, but they do show some structure — perhaps a bar or a ring that may eventually give rise to more disc-like features.

This image zooms in on one area of the new Hubble image, the stunning Lenticular galaxy (in the lower left of the first image) with numerous background galaxies visible as well.

The cluster’s position in space – near the Milky Way’s north pole— places it in an area not obscured by dust and gas, making it easily visible from Earth.

Original News Source: Hubble Site

Does your cell phone bill ever reach astronomical proportions? Maybe you’re doing too much texting. One space scientist has worked out that sending texts via mobile phones works out to be far more expensive than downloading data from the Hubble Space Telescope. Dr. Nigel Bannister from the University of Leicester looked at the cost of obtaining a megabyte of data from Hubble and compared it with the cost of sending a text. His calculations? “The bottom line is texting is at least 4 times more expensive than transmitting data from Hubble, and is likely to be substantially more than that.”

Bannister says, “The maximum size for a text message is 160 characters, which takes 140 bytes because there are only 7 bits per character in the text messaging system, and we assume the average price for a text message is 5 pence (about .10 USD). There are 1,048,576 bytes in a megabyte, so that’s 1 million/140 = 7490 text messages to transmit one megabyte. At 5p each, that’s £374.49 ($734.25 USD) per MB – or about 4.4 times more expensive than the ‘most pessimistic’ estimate for Hubble Space Telescope transmission costs.”

Dr Bannister said NASA provided the numbers of £8.85 ($17.33 USD) per megabyte for the transmission of data from HST to the Earth.

“This doesn’t include the cost of the ground stations and the time of the personnel along the way, but it is an unambiguous number for that part of the process. So that’s £8.85 to get each MB from Hubble, to the first point of contact on the ground, but no further. Hence we need to go a little bit further to estimate exactly how much it costs to transmit data from Hubble to the end user – i.e. to the data archive which scientists can access. This is difficult, so I had to make some conservative assumptions.”

Dr. Bannister estimated the cost of the data from Hubble could vary between £8.85 and £85 per MB- much cheaper than the £374.49 per MB cost of transmitting one MB of text.

Surprised by the results, Bannister said, “Hubble is by no means a cheap mission – but the mobile phone text costs were pretty astronomical!”

Original News Source: Physorg.com

Astronomers looking at galaxies in the universe’s distant past were surprised to find some compact, very young galaxies that have masses similar to a mature, grown-up galaxy. Using the Hubble Space Telescope, astronomers discovered nine small galaxies, each weighing in at 200 billion times the mass of the Sun. The galaxies, each only 5,000 light-years across, are a fraction of the size of today’s adult galaxies but contain approximately the same number of stars. Each galaxy could fit inside the central hub of our Milky Way Galaxy.

Using the Hubble in conjunction with Keck Observatory in Hawaii, astronomers were able to study the galaxies as they existed 11 billion years ago, when the Universe was less than 3 billion years old.

“Seeing the compact sizes of these galaxies is a puzzle”, said Pieter G. van Dokkum of Yale University in New Haven, Connecticut, USA, who led the study. “No massive galaxy at this distance has ever been observed to be so compact. These galaxies would have to change a lot over 11 billion years, growing five times bigger. They could get larger by colliding with other galaxies, but such collisions may not be the complete answer. It is not yet clear how they would build themselves up to become the large galaxies we see today.”

To determine the sizes of the galaxies, the team used the Near Infrared Camera and Multi-Object Spectrometer on Hubble. For the Keck observations, a powerful laser was used to correct for image blurring caused by the Earth’s atmosphere. Only Hubble, Keck and ESO’s Very Large Telescope are really able to measure the sizes of these galaxies as they are very small and far away.

The ultra-dense galaxies might comprise half of all galaxies of that mass 11 billion years ago, van Dokkum said, forming the building blocks of today’s largest galaxies.

How did these small, crowded galaxies form? One way, suggested van Dokkum, involves the interaction of dark matter and hydrogen gas in the nascent Universe. Dark matter is an invisible form of matter that accounts for most of the Universe’s mass. Shortly after the Big Bang, the Universe contained an uneven landscape of dark matter. Hydrogen gas became trapped in pockets of the invisible material and began spinning rapidly in dark matter’s gravitational whirlpool, forming stars at a furious rate.

Based on the galaxies’ mass, which is derived from their color, the astronomers estimated that the stars are spinning around their galactic disks at roughly 400 to 500 kilometers per second. Stars in today’s galaxies, by contrast, are traveling at about half that speed because they are larger and rotate more slowly than the compact galaxies.

The astronomers say that these galaxies are ideal targets for the Wide Field Camera 3, which is scheduled to be installed aboard Hubble during upcoming Servicing Mission 4 in the fall of 2008.

Original News Source: European Hubble Space Telescope Homepage