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Showing posts with label astrophysics. Show all posts
Showing posts with label astrophysics. Show all posts

Saturday, May 18, 2013

Astrophile: Saturn's egg moon Methone is made of fluff - space - 17 May 2013 - New Scientist

"Out among Saturn's menagerie of moons, a shiny white egg rests in a nest of ice crystals.
Named Methone, this small, oval moon was seen in close-up for the first time last year by NASA's Cassini spacecraft. Methone is utterly unlike the other small balls of ice and rock that dot the solar system, which are deeply scarred by impacts. Instead it is smooth, with not a hill or pockmark in sight. Now astronomers may have a clue as to why: Methone is made of lightweight fluff."Astrophile: Saturn's egg moon Methone is made of fluff - space - 17 May 2013 - New Scientist

Thursday, May 16, 2013

Deep Space Beacon


Pulsed gamma rays from the Vela pulsar from photons detected by Fermi's Large Area Telescope. The Vela pulsar is the brightest persistent source of gamma rays in the sky. The bluer colour in the latter part of the pulse indicates the presence of gamma rays with energies exceeding a billion electron volts (1 GeV). For comparison, visible light has energies between two and three electron volts. Red indicates gamma rays with energies less than 300 million electron volts (MeV); green, gamma rays between 300 MeV and 1 GeV; and blue shows gamma rays greater than 1 GeV. The image frame is 30 degrees across. The background, which shows diffuse gamma-ray emission from the Milky Way, is about 15 times brighter here than it actually is.
Source Goddard Space Flight Center
Author Roger Romani (Stanford University) (Lead), Lucas Guillemot (CENBG), Francis Reddy (SPSYS)

Saturday, March 23, 2013

C/2011 L4 PANSTARRS

Comet C/2011 L4 PANSTARRS as seen from Mount Dale, Western Australia. Image credit: Astronomy Education Services/Gingin Observatory


Image obtained after processing with AstroFracTool the original at
http://www.nasa.gov/mission_pages/asteroids/news/comet20130307.html




Friday, June 1, 2012

NGC 891

Another superb image at http://apod.nasa.gov/apod/ap120526.html
" This sharp cosmic portrait features NGC 891. .. At first glance, it has a flat, thin, galactic disk and a central bulge cut along the middle by regions of darkobscuring dust. The combined image data also reveal the galaxy's young blue star clusters and telltale pinkish star forming regions. And remarkably apparent in NGC 891's edge-on presentation are filaments of dust that extend hundreds of light-years above and below the center line. The dust has likely been blown out of the disk by supernova explosions or intense star formation activity. "

Here the NASA image after processing with AstroFracTool and Iris


Transit of Mercury

Very beautiful image at http://apod.nasa.gov/apod/ap120527.html Image Credit: SOHO - EIT Consortium, NASA
"The diminutive disk of Mercury, the solar system's innermost planet, spent about five hours crossing in front of the enormous solar disk in 2003 ... the horizon was certainly no problemfor the sun-staring SOHO spacecraft. Seen as a dark spot, Mercury progresses from left to right (top panel to bottom) in these four images from SOHO's extreme ultraviolet camera. The panels' false-colors correspond to different wavelengths in the extreme ultraviolet which highlight regions above the Sun's visible surface."

Here the image from NASA after processing with IRIS




Transit of Venus

"The next transit of Venus, where Venus appears as a dark spot in front of the Sun, will begin at 22:09 UTC on 5 June 2012, and will finish at 04:49 UTC on 6 June.[1] Depending on the position of the observer, the exact times can vary by up to ±7 minutes. Transits of Venus occur in pairs that are eight years apart: the previous transit was in June 2004, and the next pair of transits will occur in December 2117 and December 2125." from Wikipedia

Aristarchus proposed to measure the distance to the Sun using parallax. This approach based on the geometric principles of parallax last for two thousands of years, until Edmond Halley in 1716 proposed to observe the transit of Venus. The use of Venus transits gave an estimate of 1.53×10^13 cm, 2.6% above the currently accepted value, that of l.49 × 10^13 cm. More recently, in 1910, the parallax was measured using the asteroid Eros that passed much closer to Earth than Venus. A transit of Venus happens when this planet passes directly between the Sun and Earth, appearing as a small black disk moving across the Sun bright disk. The duration of such transits is usually measured in hours.
Read more "Two amateur astronomers at Berkeley", at http://arxiv.org/abs/1202.0950

Thursday, March 1, 2012

More Planets than Stars

Microlensing suggests that our galaxy has more planets than stars, buBertram M. Schwarzschild
March 2012, http://dx.doi.org/10.1063/PT.3.1463, Physics Today
Gravitational bending of light reveals exoplanets with large orbital radii.
"Most of the more than 600 exoplanets discovered to date have been found through Doppler evidence of periodic host-star motion or photometric evidence of transits across a star’s face. Both methods are strongly biased in favor of planets with orbital radii much smaller than Earth’s, which defines 1 astronomical unit (AU). Gravitational microlensing is an alternative technique that’s most sensitive to planets a few AU from their stars. It favors very distant stars and it’s relatively unbiased as to stellar mass. Though microlensing’s discovery rate is still modest, it appeals to those who seek a representative galactic survey of planets with orbits like those of the solar system." http://www.physicstoday.org/resource/1/phtoad/v65/i3/p19_s1

Thursday, October 27, 2011

Giant Waterworld Around Naked Eye Star

Giant Waterworld Confirmed Around Naked Eye Star - Technology Review
"55 Cancri A is a Sun-like star some 40 light years away. It has an apparent magnitude of about 6 and so is visible to the naked eye in the constellation of Cancer.
This star is unusual in that it is just one of a handful that are known to have at least 5 planets. The innermost of these planets--55 Cancri e--was discovered in 2004 and has since had plenty of attention from astronomers. Various groups have observed the the changes in radial velocity that it causes its parent star. This tells them about that it orbits its star every 18 hours and that its mass is about 8 times Earth's or about half Neptune's."
"The innermost planet around 55 Cancri A is almost certainly an exotic waterworld with a radius about twice Earth's, say astronomers"

Friday, September 30, 2011

Speed of neutrinos and cosmic consequences

Let me report a part of the discussion on the speed of neutrinos by Wikipedia
"In September 2011 the OPERA collaboration released calculations showing velocities of 17-GeV and 28-GeV neutrinos exceeding the speed of light in their experiments. The authors write, "Despite the large significance of the measurement reported here and the stability of the analysis, the potentially great impact of the result motivates the continuation of our studies in order to investigate possible still unknown systematic effects that could explain the observed anomaly." This result had not been detected by previous experiments, and lies in contrast to several others. For instance, photons and neutrinos from SN 1987A were observed to have an agreement in transit time to about 1 part in 450 million, with even this difference being accounted for by light being impeded by the material of the star early in its journey. The OPERA results, in contrast, suggested that neutrinos were traveling faster than light by a factor of 1 in 40,000, i.e. that neutrino speed is 1.0000248(28)c. Had neutrinos from SN 1987A (a supernova, approximately 168,000 light-years from Earth, http://en.wikipedia.org/wiki/SN_1987A) traveled faster than light by this factor, they would have arrived at Earth several years before the photons; this was not observed to be the case. However, neutrinos from the supernova had orders of magnitude less energy than the neutrinos observed in the OPERA experiment, as the authors point out."

Friday, July 1, 2011

A far quasar

"A team of European astronomers, including UK astronomers, have discovered a bright quasar that has been beaming light since the Universe was a mere 770 million years old.
The brilliant beacon, named ULAS J1120+0641, is powered by a black hole with a mass two billion times that of the Sun. Located at a redshift – a term relating to astronomical distances – of 7.1, its light has taken 12.9 billion years to reach us. The next most distant quasar is seen at 870 million years after the big bang, or a redshift of 6.4, although gamma ray bursts have been detected at greater distances of 8.6 and 8.2 redshifts."
Most distant quasar shines brightly

Friday, June 10, 2011

A new type of supernova

"A new type of supernova that shines up to 10 times brighter than any previously recorded has been discovered by an international team of astronomers. However, the team has yet to explain the exact mechanism that drives this new type of exploding star, with existing models failing to reproduce the radiation emanating from this new class of violent events."
New type of supernova outshines the rest - physicsworld.com

Vídeo: espectacular explosión solar

Una espectacular erupción solar fue captada por la NASA. Aunque sólo es de impacto medio, las imágenes de la eyección de masa coronal son impresionantes.
Vídeo: espectacular explosión solar

Wednesday, May 25, 2011

Telescope optics set to aid gravitational detection

"A British team is designing the optics for a telescope that will be able to detect the gravitational effects of violent cosmic events, such as when two black holes collide.
The €790m (£688m) Einstein Telescope should be completed by 2025, by which time it will be capable of detecting gravitational waves around 100 orders of magnitude fainter than current devices can."
Telescope optics set to aid gravitational detection News The Engineer

Friday, May 20, 2011

Unbound planets could abound in the universe

"Ten planets that appear to be drifting in interstellar space have been spotted by an international team of astronomers. The planets are so far from any host stars that they may not orbit a star at all, and could be drifting unbound through space. The team believes that such rogue planets could outnumber normal stars almost 2:1 and their existence could confirm computer simulations of solar-system formation."
Unbound planets could abound in the universe - physicsworld.com

Sunday, May 1, 2011

Icy telescope

"The Baikal underwater telescope NT-200 in Russia has been set up to capture elusive neutrino particles in a bid to unravel the secrets of the formation of the Universe.
At 1.1 km beneath the surface of the world's deepest lake and pointing towards the centre of the Earth, it is one of the most unusual telescopes on the planet."
http://www.bbc.co.uk/news/science-environment-11384614

Friday, April 29, 2011

Alcohol haze at galactic heart

BBC NEWS, Tuesday, 9 October, 2001, 14:34 GMT 15:34 UK
Alcohol haze at galactic heart
Online science editor Dr David Whitehouse
"The detection of yet more alcohol in a giant molecular cloud near the centre of our galaxy could give clues to the origin of complex organic molecules in space.Astronomers have long been seeking evidence of this particular alcohol to help explain how these life-promoting substances got started. ... Vinyl alcohol, actually a non-inebriating complex organic molecule, is an important part of many chemical reactions on Earth, and the last of the three stable members of the C2H4O group of molecules to be discovered in interstellar space. It was detected in a massive molecular cloud called Sagittarius B2, located 26,000 light-years from Earth, near the centre of our galaxy....The specific radio signature of vinyl alcohol was first detected using a 12-metre radio telescope during May and June of 2001. Results from the observations will soon be published in Astrophysical Journal Letters. Of the approximately 125 molecules so far detected in interstellar space, scientists believe that most are formed by a simple process in which smaller molecules (and occasionally atoms) stick together after they collide. Since the 1970s, scientists have speculated that molecules could form on the microscopic dust grains that drift in interstellar clouds. These dust grains are thought to trap the fast-moving molecules. The surface of these grains could act as a catalyst enabling the chemical reactions that form vinyl alcohol and other complex molecules. "Scientists speculate that since the dust lies near an area where young stars are forming, the energy from these stars could evaporate the icy surface layers of the grains, liberating the molecules from their chilly nurseries, depositing them into interstellar space where they can be detected by sensitive radio antennae on Earth.

Dark matter and galactic haze

"Annihilating dark matter at the heart of the Milky Way could account for signals detected by two space telescopes, according to a pair of US physicists. If true, the theory provides a new indirect measurement of one of astronomy's most elusive entities. However, some physicists believe that we don't know enough about the galactic core – or dark matter – to come to this conclusion."
Does dark matter link gamma rays to galactic haze? - physicsworld.com

Thursday, April 14, 2011

Stellar vibrations

"Scientists have long known that the atmosphere of the Sun oscillates. In the same way seismologists use earthquakes to model the interior of the Earth, helioseismologists use vibrations observed on the Sun to probe deeper into our star. Oscillations of about 25 other stars have also been studied in the emerging field of asteroseismology. Now, thanks to the Kepler space telescope, a team led by Bill Chaplin, at the University of Birmingham, UK, has increased this figure significantly."
Kepler picks up stellar vibrations - physicsworld.com

Monday, April 11, 2011

SNEWS

When a red giant star collaps on itself a burst of neutrinos is produced. This occurs before that light is emitted in the explosion, The SuperNova Early Warning System (SNEWS) is a network of neutrino detectors designed to give an early warning to astronomers of a supernova event in the Milky Way. The neutrino pulse from supernova 1987A was detected 3 hours before the photons.
The current members of SNEWS are Borexino, Super-Kamiokande, LVD, SNO and IceCube.
http://en.wikipedia.org/wiki/Supernova_Early_Warning_System

Tuesday, March 29, 2011

Europa, Ganymede, Callisto

PIA01656: Europa, Ganymede, and Callisto: Surface comparison at high spatial resolution, NASA, JPL
"These images show a comparison of the surfaces of the three icy Galilean satellites, Europa, Ganymede, and Callisto, scaled to a common resolution of 150 meters per picture element (pixel). Despite the similar distance of 0.8 billion kilometers to the sun, their surfaces show dramatic differences."Catalog Page for PIA01656