discoverynews:

“So, what do you do for a living?” “I just analyze data from radio telescopes… oh and I take pictures of black holes.” Pretty awesome job.

Do Black Holes Really Look Like This?

A giant black hole is thought to lurk at the center of the Milky Way, but it has never been directly seen. Now astronomers have predicted what the first pictures of this black hole will look like when taken with technology soon to be available.

In particular, researchers have found that pictures of a black hole ― or, more precisely, the boundaries around them ― will take a crescent form, rather than the blobby shape that is often predicted. Read more…

physicsphysics:

It’s Official! Water Ice Discovered on Mercury

It’s time to add Mercury to the list of worlds where you can go ice-skating. Confirming decades of suspicion, a NASA spacecraft has spotted vast deposits of water ice on the planet closest to the sun.

Temperatures on Mercury can reach 800 degrees Fahrenheit (427 degrees Celsius), but around the north pole, in areas permanently shielded from the sun’s heat, NASA’s Messenger spacecraft found a mix of frozen water and possible organic materials.

Evidence of big pockets of ice is visible from a latitude of 85 degrees north up to the pole, with smaller deposits scattered as far away as 65 degrees north.

The find is so enticing that NASA will direct Messenger’s observation toward that area in the coming months — when the angle of the sun allows — to get a better look, said Gregory Neumann, a Messenger instrument scientist at NASA’s Goddard Space Flight Center in Maryland. [Latest Mercury Photos from Messenger]

“There is an ongoing campaign, when the spacecraft permits, to look further northward,” said Neumann, the lead author of one of three Mercury studies published online in the Nov. 29 edition of the journal Science.

Researchers also believe the south pole has ice, but Messenger’s orbit has not allowed them to obtain extensive measurements of that region yet.

Messenger will spiral closer to the planet in 2014 and 2015 as it runs out of fuel and is perturbed by the sun’s and Mercury’s gravity. This will let researchers peer closer at the water ice as they figure out how much is there.

[More at Space.com]

for-all-mankind:

Atlantis as seen from the ISS, 19 July 2011. Backing away from the station for the final time, the Shuttle is hidden in Earth’s Shadow.

ikenbot:

Arp 188 & The Tadpole’s Tail

In this stunning vista, based on image data from the Hubble Legacy Archive, distant galaxies form a dramatic backdrop for disrupted spiral galaxy Arp 188, the Tadpole Galaxy.

Image Credit: Hubble Legacy Archive, ESA, NASA; Processing - Bill Snyder (Heavens Mirror Observatory)

The cosmic tadpole is a mere 420 million light-years distant toward the northern constellation Draco. Its eye-catching tail is about 280 thousand light-years long and features massive, bright blue star clusters. One story goes that a more compact intruder galaxy crossed in front of Arp 188 - from right to left in this view - and was slung around behind the Tadpole by their gravitational attraction.

During the close encounter, tidal forces drew out the spiral galaxy’s stars, gas, and dust forming the spectacular tail. The intruder galaxy itself, estimated to lie about 300 thousand light-years behind the Tadpole, can be seen through foreground spiral arms at the upper left. Following its terrestrial namesake, the Tadpole Galaxy will likely lose its tail as it grows older, the tail’s star clusters forming smaller satellites of the large spiral galaxy.

ikenbot:

X 1.2 Flare

The Sun emitted a significant solar flare on Oct. 22, 2012, peaking at 11:17 p.m. EDT. The flare came from an active region on the left side of the sun that has been numbered AR 1598, which has already been the source of a number of weaker flares. It was captured by SDO in the 131 Angstrom wavelength of extreme ultraviolet light. The movies covers less than an hour.

This flare was classified as an X.1-class flare. “X-class” denotes the most intense flares, while the number provides more information about its strength. An X2 is twice as intense as an X1, an X3 is three times as intense, and so on. An X-class flare of this intensity can cause degradation or blackouts of radio communications for about an hour. This event did produce an impulsive R3 Solar Flare Radio Blackout. R3 is considered “Strong”, meaning a wide area blackout of HF radio communication, loss of radio contact for about an hour on the sunlit side of Earth.

ikenbot:

How to Build a Planet: Heavy Metals Are Key Ingredients

Image: An artist conception of a newly formed star surrounded by a swirling protoplanetary disk of dust and gas, where debris coalesces to create rocky ‘planetesimals’ that collide and grow to eventually form planets. A new study suggests small rocky planet may actually be widespread in our Milky Way galaxy. Credit: University of Copenhagen, Lars A. Buchhave

Planets may not be able to form without a heaping helping of heavy elements such as silicon, titanium and magnesium, a new study suggests.

Stars that host planets have higher concentrations of such “metals” — astronomer-speak for elements heavier than hydrogen and helium — compared to iron than do planetless stars, the study found.

“To form planets, one needs heavy elements,” said lead author Vardan Adibekyan, of the Centre for Astrophysics of the University of Porto in Portugal.

Connected at birth

Planets coalesce from the disk of dust and gas left over after the birth of their parent star. According to the leading theory of planet formation, the core accretion model, small particles clump together, growing larger and larger until they produce protoplanets.

Scientists have long suspected that stars with higher metallicities are more likely to have planets orbiting them. Iron has long been a primary indicator.

“Usually, in stellar physics, people use the iron content as a proxy of overall metallicity,”

Full Article

I have loved the stars too fondly to be fearful of the night.

ikenbot:

Huge Mars Rover Set for Nerve-Wracking Landing on Red Planet Today

After 8 1/2 months crossing the millions of miles between planets, the biggest and most complex rover ever sent to another world is now on its final approach for a hair-raising touchdown on Mars.

NASA’s 1-ton Curiosity rover is set to land inside the Red Planet’s Gale Crater at 10:31 p.m. PDT tonight (Aug. 5; 1:31 a.m. EDT and 0531 GMT on Aug. 6). As with any planetary landing, success is not a given, and tensions may be especially high tonight given Curiosity’s elaborate, unprecedented landing sequence.

The rover’s spacecraft will barrel into the Martian atmosphere at 13,000 mph (21,000 kph), then deploy a huge supersonic parachute to slow it to about 200 mph (320 kph). Rockets will slow the vehicle’s descent further, to less than 2 mph (3.2 kph), setting the stage for a spectacular “sky crane” maneuver.

Curiosity’s descent stage will lower the enormous rover to the Martian surface on cables, then fly off to crash-land intentionally a safe distance away. Engineers have dubbed the entire sequence “seven minutes of terror” (watch), because that’s how long it’ll take from atmospheric entry to touchdown.

ikenbot:

Oddball Pulsating Star Hiccups as It Spins

Astronomers have discovered a weird compact spinning star whose rotation has sped up slightly, causing it to be hidden until now.

The star is what’s called a pulsar, made of the condensed remnants of a normal star that have been squeezed down to a much smaller volume. This compression has caused the star’s rotation to accelerate to roughly seven times a second.

Pulsars are so called because they appear to pulse on and off, as beams of light pointing from their poles sweep toward Earth and away.

Full Article

ikenbot:

Wave Maker

The Cassini spacecraft catches Saturn’s moon Daphnis making waves and casting shadows from the narrow Keeler Gap of the planet’s A ring in this view taken around the time of Saturn’s August 2009 equinox.

peteuplink:

Click to Enlarge

For the first time, dark galaxies — an early phase of galaxy formation, predicted by theory but unobserved until now — may have been spotted. These objects are essentially gas-rich galaxies without stars. Using ESO’s Very Large Telescope, an international team thinks they have detected these elusive objects by observing them glowing as they are illuminated by a quasar.

Dark galaxies are small, gas-rich galaxies in the early Universe that are very inefficient at forming stars. They are predicted by theories of galaxy formation and are thought to be the building blocks of today’s bright, star-filled galaxies. Astronomers think that they may have fed large galaxies with much of the gas that later formed into the stars that exist today.

Because they are essentially devoid of stars, these dark galaxies don’t emit much light, making them very hard to detect.  For years astronomers have been trying to develop new techniques that could confirm the existence of these galaxies. Small absorption dips in the spectra of background sources of light have hinted at their existence. However, this new study marks the first time that such objects have been seen directly.

“Our approach to the problem of detecting a dark galaxy was simply to shine a bright light on it.” explains Simon Lilly (ETH Zurich, Switzerland), co-author of the paper. “We searched for the fluorescent glow of the gas in dark galaxies when they are illuminated by the ultraviolet light from a nearby and very bright quasar. The light from the quasar makes the dark galaxies light up in a process similar to how white clothes are illuminated by ultraviolet lamps in a night club.” [1]

The team took advantage of the large collecting area and sensitivity of the Very Large Telescope (VLT), and a series of very long exposures, to detect the extremely faint fluorescent glow of the dark galaxies. They used the FORS2 instrument to map a region of the sky around the bright quasar [2] HE 0109-3518, looking for the ultraviolet light that is emitted by hydrogen gas when it is subjected to intense radiation. Because of the expansion of the Universe, this light is actually observed as a shade of violet by the time it reaches the VLT. [3]

“After several years of attempts to detect fluorescent emission from dark galaxies, our results demonstrate the potential of our method to discover and study these fascinating and previously invisible objects,” says Sebastiano Cantalupo (University of California, Santa Cruz), lead author of the study.

The team detected almost 100 gaseous objects which lie within a few million light-years of the quasar. After a careful analysis designed to exclude objects where the emission might be powered by internal star-formation in the galaxies, rather than the light from the quasar, they finally narrowed down their search to 12 objects. These are the most convincing identifications of dark galaxies in the early Universe to date.

The astronomers were also able to determine some of the properties of the dark galaxies. They estimate that the mass of the gas in them is about 1 billion times that of the Sun, typical for gas-rich, low-mass galaxies in the early Universe. They were also able to estimate that the star formation efficiency is suppressed by a factor of more than 100 relative to typical star-forming galaxies found at similar stage in cosmic history. [4]

“Our observations with the VLT have provided evidence for the existence of compact and isolated dark clouds. With this study, we’ve made a crucial step towards revealing and understanding the obscure early stages of galaxy formation and how galaxies acquired their gas”, concludes Sebastiano Cantalupo.

The MUSE integral field spectrograph, which will be commissioned on the VLT in 2013, will be an extremely powerful tool for the study of these objects.

Notes

[1] Fluorescence is the emission of light by a substance illuminated by a light source. In most cases, the emitted light has longer wavelength than the source light. For instance, fluorescent lamps transform ultraviolet radiation — invisible to us — into optical light. Fluorescence appears naturally in some compounds, such as rocks or minerals but can be also added intentionally as in detergents that contain fluorescent chemicals to make white clothes appear brighter under normal light.

[2] Quasars are very bright, distant galaxies that are believed to be powered by supermassive black holes at their centres. Their brightness makes them powerful beacons that can help to illuminate the surrounding area, probing the era when the first stars and galaxies were forming out of primordial gas.

[3] This emission from hydrogen is known as Lyman-alpha radiation, and is produced when electrons in hydrogen atoms drop from the second-lowest to the lowest energy level. It is a type of ultraviolet light. Because the Universe is expanding, the wavelength of light from objects gets stretched as it passes through space. The further light has to travel, the more its wavelength is stretched. As red is the longest wavelength visible to our eyes, this process is literally a shift in wavelength towards the red end of the spectrum — hence the name ‘redshift’. The quasar HE 0109-3518 is located at a redshift of z = 2.4, and the ultraviolet light from the dark galaxies is shifted into the visible spectrum. A narrow-band filter was specially designed to isolate the specific wavelength of light that the fluorescent emission is redshifted to. The filter was centered at around 414.5 nanometres in order to capture Lyman-alpha emission redshifted by z=2.4 (this corresponds to a shade of violet) and has a bandpass of only 4 nanometres.

[4] The star formation efficiency is the mass of newly formed stars over the mass of gas available to form stars. They found these objects would need more than 100 billion years to convert their gas into stars. This result is in accordance with recent theoretical studies that have suggested that gas-rich low-mass haloes at high redshift may have very low star formation efficiency as a consequence of lower metal content.

More information

This research was presented in a paper entitled “Detection of dark galaxies and circum-galactic filaments fluorescently illuminated by a quasar at z=2.4”, by Cantalupo et al. to appear in Monthly Notices of the Royal Astronomical Society.

The team is composed of Sebastiano Cantalupo (University of California, Santa Cruz, USA), Simon J. Lilly (ETH Zurich, Switzerland) and Martin G. Haehnelt (Kavli Institute for Cosmology, Cambridge, United Kingdom).

The year 2012 marks the 50th anniversary of the founding of the European Southern Observatory (ESO). ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 40-metre-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links

• Research paper
• Photos of the VLT
• Other images taken with the VLT

Contacts

Sebastiano Cantalupo
University of California
Santa Cruz, USA
Tel: +1 831 459 5891
Email: cantal@ucolick.org

Simon J. Lilly
Institute for Astronomy, ETH Zurich
Zurich, Switzerland
Tel: +41 44 633 3828
Email: simon.lilly@phys.ethz.ch

Richard Hook
ESO, La Silla, Paranal, E-ELT & Survey Telescopes Press Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org

peteuplink:

Click to Enlarge

This image snapped by the NASA/ESA Hubble Space Telescope reveals an exquisitely detailed view of part of the disc of the spiral galaxy NGC 4565. This bright galaxy is one of the most famous examples of an edge-on spiral galaxy, oriented perpendicularly to our line of sight so that we see right into its luminous disc. NGC 4565 has been nicknamed the Needle Galaxy because, when seen in full, it appears as a very narrow streak of light on the sky.

The edgewise view into the Needle Galaxy shown here looks very similar to the view we have from our Solar System into the core of the Milky Way. In both cases ribbons of dust block some of the light coming from the galactic disc. To the lower right, the dust stands in even starker contrast against the copious yellow light from the star-filled central regions. NGC 4565’s core is off camera to the lower right. For a full view of NGC 4565 for comparison’s sake, see this wider field of view from ESO’s Very Large Telescope.

Studying galaxies like NGC 4565 helps astronomers learn more about our home, the Milky Way. At a distance of only about 40 million light-years, NGC 4565 is relatively close by, and being seen edge-on makes it a particularly useful object for comparative study. As spiral galaxies go, NGC 4565 is a whopper — about a third as big again as the Milky Way.

The image was taken with Hubble’s Advanced Camera for Surveys and has a field of view of approximately 3.4 by 3.4 arcminutes.

A version of this image was entered into the Hubble’s Hidden Treasures Image Processing Competition by contestant Josh Barrington. Hidden Treasures is an initiative to invite astronomy enthusiasts to search the Hubble archive for stunning images that have never been seen by the general public. The competition has now closed and the results will be published soon.

Credit:

ESA/Hubble & NASA

ikenbot:

NGC 4725

Copyright: Emil Ivanov

discoverynews:

How to Become a Planet Hunter

This last month saw a boom in planetary sightings across the world. Wherever you observed the night sky from you couldn’t fail to have seen, and been impressed by, the view of Venus and Jupiter dancing around in the twilight after the sun had set.

While these two planets were setting, Mars and Saturn were rising in the East, continuing the celestial show. It’s easy enough to still spot these planets with the naked eye, but to really get the most out of them a telescope or powerful binoculars are needed.

There is no better time than now to learn about how to get the most out of your equipment for planet spotting.

First things first: magnification. To be able to see any decent level of detail, a magnification of at least 20 is needed. Anything less than this and you’ll just see the planets as bright stars.

keep reading

ikenbot:

NASA Report: Greenhouse Gases, Not Sun, Driving Warming

A recent, prolonged lull in the sun’s activity did not prevent the Earth from absorbing more solar energy than it let escape back into space, a NASA analysis of the Earth’s recent energy budget indicates.

An imbalance like this drives global warming — since more energy is coming in than leaving — and, because it occurred during a period when the sun was emitting comparatively low levels of energy, the imbalance has implications for the cause of global warming.

The results confirm greenhouse gases produced by human activities are the most important driver of global climate change, according to the researchers.

They found that the Earth absorbed 0.58 watts of excess energy per square meter than escaped back into space during the study period from 2005 to 2010, a time when solar activity was low. By comparison, the planet receives 0.25 watts less energy per square meter during a solar minimum, than during a period of maximum activity in the sun’s 11-year cycle. (Currently, the sun is in the midst of Solar Cycle 24, with activity expected to ramp up toward solar maximum in 2013.)