Bellatrix Orionis

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Kepler's Diamond Mine of Stars. Image credit: NASA/Ames/JPL-Caltech

NASA’s Kepler spacecraft has taken its first images of the star-rich sky where it will soon begin hunting for Earth like planets.

These images show Kepler’s target which is s patch of sky in the Cygnus-Lyra region of the Milky Way (our galaxy).  One image shows millions of stars in Kepler’s full field of view, whilst tow others zoom in on portions of the larger region.  Further images can be seen online.

One of the images from Kepler shows its entire field of viewwhich is  a 100-square-degree portion of the sky.  The region is estimated 4.5 million stars, more than 100,000 of which were selected as ideal candidates for planet hunting.

Two other views focus on just one-thousandth of the full field of view.  In one image, a cluster of stars located about 13,000 light-years from Earth, called NGC 6791, can be seen in the lower left corner.  The other image zooms in on a region containing a star called Tres-2, with a known Jupiter-like planet orbiting every 2.5 days.

Kepler will spend the next three-and-a-half years searching more than 100,000 pre-selected stars for signs of planets.  It is expected to find a variety of worlds, from large, gaseous ones, to rocky ones as small as Earth.  The mission is the first with the ability to find planets like ours .

To find the planets, Kepler will stare at one large patch of sky for its entire lifetime.  It will be  looking for periodic changes in the light from the stars that occur as planets circle in front of their stars and partially block the light.  Its 95-megapixel camera, the largest ever launched into space, can detect tiny changes in a star’s brightness of only 20 parts per million.

Over the next few weeks Kepler’s instruments will be calibrated.  Once this has been done then Kepler will begin planet hunting.

Credits: X-ray: NASA/CXC/CfA/F. Massaro et al.; Optical: NASA/STScI/C.P. O'Dea et al.; Radio: NSF/VLA/CfA/F. Massaro, E. Liuzzo, A. Bonafede et al.

The intriguing appearance of galaxy 3C305 is thought to be cause by activity from a supermassive black hole which is located about 600 million light years away from Earth. The structures in the image on the left in red and light blue are X-ray and optical images from the Chandra X-ray Observatory and Hubble Space Telescope respectively.  The optical data is from oxygen emission only and does not show the full extent of the galaxy.  Radio data are shown in darker blue and are from the National Science Foundation’s Very Large Array in New Mexico, as well as the Multi-Element Radio-Linked Interferometer Network in the United Kingdom.

An unexpected feature of this multiwavelength image of 3C305 is that the radio emission which is produced by a jet from the central black hole does not closely overlap with the X-ray data.  The X-ray emission does appear to be associated with the optical emission.

Due to this information astronomers believe that th x-ray emission could be caused by either one of two different effects. One option is jets from the supermassive black hole (not visible in this image) are interacting with interstellar gas in the galaxy and heating it enough for it to emit X-rays.  In this scenario, gas heated by shocks would lie ahead of the jets. The other possibility is that bright radiation from regions close to the black hole infuses enough energy into the interstellar gas to cause it to glow.  Further information will be needed to decide which of these two alternatives is what is happening.

Credit: X-ray: NASA/CXC/M.Markevitch et al. Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al. Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/D.Clowe et al.

The Bullet Cluster also known as 1E 0657-556 was formed when two large clusters of galaxies collided.  This is thought to have been the most energetic event in the universe since the Big Bang.

The Chandra X-ray Observatory detected hot gas (shown as pink clumps in this composite image) which contains most of the baryonic matter in the two clusters.  The bullet-shaped clump on the right is the hot gas from one cluster, which passed through the hot gas from the other larger cluster during the collision.  An optical image from Magellan and the Hubble Space Telescope shows the galaxies in orange and white. The blue areas in this image depict where astronomers find most of the mass in the clusters.  Most of the matter in the clusters (blue) is clearly separate from the normal matter (pink), giving direct evidence that nearly all of the matter in the clusters is dark.

When the galaxies collided the hot gas in each cluster was slowed by a drag force, similar to air resistance.  In contrast, the dark matter was not slowed by the impact.  This is because dark matter does not interact directly with itself or the gas except through gravity.  During the collision the dark matter clumps from the two clusters moved ahead of the hot gas, producing the separation of the dark and normal matter seen in this image.  If hot gas was the most massive component in the clusters, as suggested by alternative theories of gravity, such an effect would not be seen.  Instead, this result shows that dark matter is required.

Credit: NASA, ESA, P. Challis and R. Kirshner (Harvard-Smithsonian Center for Astrophysics)

One of the brightest exploding stars in more than 400 years was discovered 20 years ago by astronomers.  Supernova 1987a as it’s been called has fascinated astronomers since its discover.  Even the Hubble Space Telescope has been monitoring the aftermath of the explosion.

This image on the right shows the entire region around the supernova.  The most prominent feature in the image is a ring with dozens of bright spots.  A shock wave of material unleashed by the stellar blast is slamming into regions along the ring’s inner regions, heating them up, and causing them to glow.  The ring which is approximately a light-year across, was probably shed by the star about 20,000 years before it exploded.

The first bright spot was observed by astronomers in 1997, but since then dozens of spots have appears around the ring.  Only by using the Hubble Space telescope can the individual spots been seen.  Astronomers expect the ring to be ablaze in the next few years as it absorbs the full force of the crash.  It is hoped that the ring will become so bright that it will illuminate the area surrounding the star and provide astronomers with new information on how the star shed the material before it exploded.

The pink object in the center of the ring is debris from the supernova blast.  The glowing debris is being heated by radioactive elements, principally titanium 44, created in the explosion.  The debris will continue to glow for many decades.

The origin of a pair of faint outer red rings, located above and below the doomed star, is a mystery.  The two bright objects that look like car headlights are a pair of stars in the Large Magellanic Cloud.  The supernova is located 163,000 light-years away in the Large Magellanic Cloud.

The image was taken in December 2006 with Hubble’s Advanced Camera for Surveys.

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

As summer approaches the annual Mars hoax does the rounds again.  It appears in the form of a PowerPoint attachment in an email entitled “Mars Spectacular”, unfortunately no one knows were it originated from.It first appeared during the summer of 2004.

The email claims that on the night of 27 August, Mars will come closer to Earth than it has in the past 60,000 years, thereby offering spectacular views of the red planet.  It even claims that Mars will appear as large as the full moon.  Now that comment alone should be a give away.  How can Mars which is 189 million miles away from Earth appear as large as the Moon, which is 238,000 miles from Earth?  Despite Mars being larger (approximately 4,213 miles, or 6,780 km. in diameter) than the Moon (about 2,160 miles, or 3,475 km) because of it’s great distance from Earth it’s never going to appear as large as the Moon.

Mars has passed relatively close to Earth, but this happened on 27 April 2003.  The Hubble Space Telescope took some snap shots, but viewed from Earth, Mars still appeared as nothing more spectacular than a rather bright yellowish-orange star.

Mars is actually much dimmer this year no were near as noticable as it was in 2003.

Image credit: NASA/JPL-Caltech

The image on the right shows an artist’s idea of a hypothetical young planet circling  a cool star.  Observations from NASA’s Spitzer Space Telescope have hinted that planets around cool stars, the M-dwarfs and brown dwarfs that are very widespread thoughtout our galaxy may possess a different mix of life-forming than our young Earth.

Some of the chemicals that created life on Earth are thought to have been carried by meteorites that crash landed.  Other chemicals are thought to have come from dust and gas swirling around a young Sun

Astronomers don’t know if these same life-generating processes are taking place around stars that are cooler than our sun, as the Spitzer observations show their disk chemistry to be different.  Spitzer detected a prebiotic molecule ( a molecule that is believed to be involved in the process leading to the origin of life), called hydrogen cyanide.  This was found in the disks around yellow stars like our Sun, but none where discovered around cooler, less massive, reddish stars.  Hydrogen cyanide is a carbon-containing, or organic compound.  Five hydrogen cyanide molecules can join up to make adenine — a chemical element of the DNA molecule found in all living organisms on Earth.

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

This is the Hubble Telescopes final image with it’s Wide Field Planetary Camera 2 (WFPC2) before it was decomissioned.

The image on the right is of planetary nebula Kohoutek 4-55 (also known as K4-55).  It’s one of several planetary nebulae named after the person who discovered them.  In this case it was a Czech astronomer called Lubos Kohoutek.

A planetary nebula contains the outer layers of a red giant star that were catapulted into interstellar space when the star was in the late stages of its life.  Ultraviolet radiation emitted from the remaining hot core of the star ionizes the ejected gas shells, causing them to glow.

In the specific case of K 4-55, a bright inner ring is surrounded by a bipolar structure.  The entire system is then surrounded by a faint red halo, seen in the emission by nitrogen gas.  This multi-shell structure is fairly uncommon in planetary nebulae.

This Hubble image was taken by WFPC2 on 4 May 2009.  The colors represent the makeup of the various emission clouds in the nebula: red represents nitrogen, green represents hydrogen, and blue represents oxygen.  K 4-55 is approximately 4,600 light-years away in the constellation Cygnus.

Credit NASA, ESA and A Reiss (STScl/JHU)

Whatever dark energy is, explanations for it have less wiggle room following a Hubble Space Telescope observation that has refined the measurement of the universe’s present expansion rate to a precision where the error is smaller than five percent.  The new value for the expansion rate, known as the Hubble constant, or H₀ (after Edwin Hubble who first measured the expansion of the universe nearly a century ago), is 74.2 kilometers per second per megaparsec (error margin of ± 3.6).  Earlier measurements made by Hubble gave the result as  72 ± 8 km/sec/megaparsec.  The new measurement is now twice as precise.

A number of refinements were used to strengthen and streamline the construction of a cosmic “distance ladder” a billion light years in length that astronomers use to establish the expansion of the universe.

Pulsating stars called Cephid vairables have been observed by the Hubble Space Telescope to provide the cosmic mile marker.  By using Hubble it removed the errors that are introduced by comparing measurements from different telescopes.

Dark energy is thought to be responsible for causing the expansion rate of the universe to accelerate.  Wit the new value for the Hubble constant the properties of dark energy can be tested and constrained.

The result is consistent with the simplest interpretation of dark energy: that it is mathematically equivalent to Albert Einstein’s hypothesized cosmological constant, introduced a century ago to push on the fabric of space and prevent the universe from collapsing under the pull of gravity.  Einstein, however, removed the constant once the expansion of the universe was discovered by Edwin Hubble.

Although the cosmological constant was dreamt up many years ago, observational evidence for dark energy didn’t come along until 11 years ago, when two studies, one led by Riess and Brian Schmidt of Mount Stromlo Observatory, and the other by Saul Perlmutter of Lawrence Berkeley National Laboratory, discovered dark energy independently, in part with Hubble observations.  Since then astronomers have been pursuing observations to better characterise dark energy.

Before the Hubble Space Telescope was launched in 1990, the estimates of the Hubble constant varied by a factor of two. In the late 1990s the Hubble Space Telescope Key Project on the Extragalactic Distance Scale refined the value of the Hubble constant to an error of only about ten percent.  This was accomplished by observing Cepheid variables at optical wavelengths out to greater distances than obtained previously and comparing those to similar measurements from ground-based telescopes.

The team used Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS) and the Advanced Camera for Surveys (ACS) to observe 240 Cepheid variable stars across seven galaxies.  One of these galaxies was NGC 4258, whose distance was very accurately determined through observations with radio telescopes.  The other six galaxies recently hosted Type Ia supernovae that are reliable distance indicators for even farther measurements in the universe.  Type Ia supernovae all explode with nearly the same amount of energy and therefore have almost the same intrinsic brightness.

By observing Cepheids with very similar properties at near-infrared wavelengths in all seven galaxies, and using the same telescope and instrument, the team was able to more precisely calibrate the luminosity of supernovae. With Hubble’s powerful capabilities, the team was able to sidestep some of the shakiest rungs along the previous distance ladder involving uncertainties in the behavior of Cepheids.

Riess would eventually like to see the Hubble constant refined to a value with an error of no more than one percent, to put even tighter constraints on solutions to dark energy.

Credit: NASA, ESA and A Feild (STScl)

Credit: NASA, N. Benitez (JHU), T. Broadhurst (The Hebrew University), H. Ford (JHU), M. Clampin(STScI), G. Hartig (STScI), G. Illingworth (UCO/Lick Observatory), the ACS Science Team and ESA

This fantastic image was produced using the Advanced Camera for Surveys (ACS) aboard the NASA/ESA Hubble Space Telescope.  A natural  ‘zoom lens’ in space has been used to boost its view of the distant universe.  As well as giving an amazing and dramatic view, it’s hoped that the results will help us to understand more about galaxy evolution and dark matter.

The cluster Abel 1689 is 2.2 billion light years away and for this image the Hubble Space telescope had to gaze at it for over 13 hours.  The natural lens that was used by Hubble was created by the gravity of the trillion stars as well as any dark matter within the cluster.  This is known as a ‘gravitational lens’ and this bends and magnifies the light of any galaxies found behind it, it also distorts their shape and creates multiple images of the individual galaxies.