02/05/2013Picture of the DayGlobular Cluster Messier 68
Messier 68 (also known as NGC 4590) is a globular cluster of some 106 light-years across and a mass of 223,000 solar masses, located about 33,600 light-years from Earth in the constellation of Hydra (The Female Water Snake), while it is approaching us at 112 – 116 kilometers per second.
More than 150 of these objects surround our Milky Way galaxy. Remarkably, Messier 68 is located almost opposite the center of our galaxy in the night sky. Most globular clusters are concentrated in the area around this center.
Mutual gravitational attraction among the cluster’s hundreds of thousands of stars keeps stellar members in check, allowing Messier 68 to hang together for many billions of years.
This spherical, star-filled region of space contains mainly very old stars. The age of the cluster is estimated at around 11.2 billion years, meaning that it began forming just 2.5 billion years after the Big Bang.
Astronomers can measure the ages of globular clusters by looking at the light of their constituent stars. The chemical elements leave signatures in this light, and the starlight reveals that stars of globular clusters typically contain fewer heavy elements, such as carbon, oxygen and iron, than stars like the Sun. Since successive generations of stars gradually create these elements through nuclear fusion, stars having fewer of them are relics of earlier epochs in the Universe. Indeed, the stars in globular clusters rank among the oldest on record, dating back more than 10 billion years.
LINK: [link to annesastronomynews.com
] Evidence There Once Was Water on the Surface of Mars!
In a paper published in the Meteoritical Society’s journal MAPS, the research team outline the results of tests on a 1.7-gram fragment of a Martian meteorite known as Nakhla, which was provided by the Natural History Museum.
Nakhla, named after the town in Egypt where it landed in 1911 after being blasted from the surface of Mars by a massive impact around 10 million years ago, has been studied for decades by scientists around the world.
Previous research on Nakhla has provided evidence of the existence of water on Mars through the presence in the meteorite of ‘secondary minerals’ – types of carbonates, hydrous silicates and sulfates most likely formed when Martian minerals reacted with liquid water.
Professor Martin Lee of the University’s School of Geographical and Earth Sciences, lead author of the paper, said: “What has been unclear in the past is exactly where the chemical elements which made up the secondary minerals within Nakhla came from.
“Using a scanning electron microscope, we examined many tiny bowl-shaped depressions, known as etch pits, in grains of the minerals olivine and augite found in the meteorite.
“What we’ve found for the first time is evidence that the etch pits were created when water dissolved the olivine and augite, and that the elements released from those minerals led to the formation of the secondary minerals.
“It’s an exciting discovery and better informs of our understanding of how water affected rock on Mars.”
By examining the amount of dissolution which occurred in the etch pits formed within the minerals, the team have also been able to estimate how long the water was present within the sample.
Professor Lee added: “From the amount of dissolution we observed, it’s likely that this particular piece of Mars was affected by water for only a few months and probably less than a year in total.
“That’s certainly not long enough to sustain a life-supporting biosphere; however, the findings of our study are from a tiny piece of a very small chunk of the surface of Mars, so it’s difficult to draw any large-scale conclusions about the presence of water on the planet or its implications for life.
LINK: [link to annesastronomynews.com
] Massive Stellar Winds are Made of Tiny Pieces
Massive stars are relatively rare, but play a very important role in recycling materials in the Universe. They burn their nuclear fuel much more rapidly than stars like the Sun, living only for millions of years before exploding as a supernova and returning most of their matter to space.
But even during their brief lives, they lose a significant fraction of their mass through fierce winds of gas driven off their surfaces by the intense light emitted from the star.
The winds from massive stars are at least a hundred million times stronger than the solar wind emitted by our own Sun and can significantly shape their surrounding environment.
They might trigger the collapse of surrounding clouds of gas and dust to form new stars or, conversely, blast the clouds away before they have the chance to get started.
Despite their important role, however, the detailed structure of the winds from massive stars remains poorly understood. Are they steady and uniform, or broken up and gusty?
Astronomers have now gained a detailed glimpse into this wind structure by taking observations with XMM-Newton spread over a decade to study variability in the X-ray emission from zeta Puppis. One of the nearest massive stars to Earth, it is bright enough to be seen with the naked eye in the constellation of Puppis, in the southern hemisphere.
The X-rays arise from collisions between slow- and fast-moving clumps in the wind, which heats them to a few million degrees. As individual colliding clumps in the wind are heated and cooled, the strength and energy of the emitted X-rays vary.
If only a small number of large fragments are present, variations in the combined emission could be large. Conversely, as the number of fragments grows, a change in the X-ray emission from any given fragment becomes less important, and the overall variability decreases.
In zeta Puppis, the X-ray emission was found to be remarkably stable over short timescales of just a few hours, pointing to a very large number of fragments. There must still be clumps in the wind to make X-rays in the first place, but there must be many of them to yield such low variability.
However, unexpected variation in the emission was seen on the order of several days, implying the presence of a few very large structures in the wind, possibly spiral-arm-like features superimposed on the highly fragmented wind co-rotating with the star.
“Studies at other wavelengths had already hinted that the winds from massive stars are not simply a uniform breeze, and the new XMM-Newton data confirm this, but also reveal hundreds of thousands of individual hot and cool pieces,” says Yaël Nazé, Université de Liège, Belgium, who led the study’s analysis.
“This is the first time constraints have been placed on the number of fragments in a stellar wind of an adult massive star, a number which far exceeds theoretical predictions.”
To fully understand these observations, improved models of stellar winds will be needed, taking into account both the large-scale emission structures and the highly fragmented wind, in order to understand how they affect mass-loss in stellar giants.
“Zeta Puppis also goes by the name Naos, which in antiquity was the name given to the innermost sanctuary of a temple, accessible to only a few people; thanks to XMM-Newton, scientists have been able to unlock the secrets of this mysterious stellar object,” adds Dr Nazé.
LINK: [link to annesastronomynews.com
] Small Asteroid to Whiz Past Earth Safely
The small near-Earth asteroid 2012 DA14 will pass very close to Earth on February 15, so close that it will pass inside the ring of geosynchronous weather and communications satellites.
NASA's Near-Earth Object Program Office can accurately predict the asteroid's path with the observations obtained, and it is therefore known that there is no chance that the asteroid might be on a collision course with Earth. Nevertheless, the flyby will provide a unique opportunity for researchers to study a near-Earth object up close.
Asteroid 2012 DA14 will be closest to Earth on Feb. 15, at about 11:24 p.m. PST (2 p.m. EST and 1924 UT), when it will be at a distance of about 27,700 kilometers (17,200 miles) above Earth's surface.
Although this is close enough for the asteroid to pass inside the ring of geosynchronous satellites, located about 35,800 kilometers (22,200 miles) above the equator, it will still be well above the vast majority of satellites, including the International Space Station.
At its closest, the asteroid will be only about 1/13th of the distance to the moon. The asteroid will fly by our planet quite rapidly, at a speed of about 17,400 mph (7.8 kilometers per second) in a south-to-north direction with respect to Earth.
Even though 2012 DA14 is coming remarkably close, it will still only appear as a point of light in the biggest of optical telescopes, because of its small size. Based on its brightness, astronomers estimate that it is only about 45 meters (150 feet) across. It will brighten only to magnitude 7.5, too faint to be seen with the naked eye, but easily visible with a good set of binoculars or a small telescope.
LINK: [link to www.spacedaily.com
] Asteroid Re-Named 'Wikipedia'
Wikipedia is loaded with articles on space. And now Wikipedia is in space, too — specifically, as an asteroid newly named "Wikipedia." The Committee for Small Body Nomenclature has renamed a main belt asteroid, previously labeled number 274301, with an official moniker: Henceforth, it's known as Wikipedia.
Astronomers at the Audrushivka Astronomical Observatory in Ukraine first spotted the asteroid in August 2008. Observatories in Caussols-ODAS in France and Mt. Lemmon Survey and Steward Observatory in Arizona also observed the asteroid. The Committee handed down the official name on Jan. 27, based on a suggestion from a member of the Wikimedia Foundation in Ukraine.
Researchers also posted some scientific facts about Wikipedia (the asteroid), including its measurement of one to two kilometers (about a mile) in diameter and its orbit, which takes it around the sun every 3.68 Earth years. And it won't collide with Earth, so no need to call Bruce Willis.
LINK: [link to www.space.com
] Sun News 02/05/2013
Product: Forecast Discussion
:Issued: 2013 Feb 05 1230 UTC
Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction CenterSolar Activity
.24 hr Summary...
Solar activity was low. There were three spotted regions on the disk
including newly-numbered Region 1669 (N08E57, Bxo/beta). Region 1669
emerged early in the period and produced occasional C-class flares
including an impulsive C6/Sf at 05/0819 UTC. It appeared to be in a
gradual growth phase. Region 1665 (N12W24, Hsx/alpha) showed little
change, while Region 1667 (N23E22, Dso/beta) showed gradual spot and
penumbral decay in its intermediate and trailing portions. There were no
Earth-directed coronal mass ejections observed during the period..Forecast...
Solar activity is likely to be low through the period (05 - 07 Feb) with
C-class flares from Region 1669. There will also be a slight chance for
an M-class flare.Energetic Particle
.24 hr Summary...
The greater than 10 MeV proton flux at geosynchronous orbit was at
background levels. The greater than 2 MeV electron flux at
geosynchronous orbit was at normal to moderate levels.
The greater than 10 MeV proton flux at geosynchronous orbit is expected
to remain at background levels though the period (05 - 07 Feb). The
greater than 2 MeV electron flux at geosynchronous orbit is expected to
be at normal levels during most of the period.Solar Wind
.24 hr Summary...
Minor changes occurred in the solar wind during the period. Wind speeds
ranged from 326 to 409 km/s. IMF Bt was variable in the 1 to 6 nT range.
IMF Bz was variable in the +/- 5 nT range. Phi data indicated a negative
(Toward) solar sector during most of the period..Forecast...
No significant changes are expected in the solar wind during the period
(05 - 07 Feb).Geospace
.24 hr Summary...
The geomagnetic field was at quiet levels..Forecast...
The geomagnetic field is expected to remain at quiet levels during the
period (05 - 07 Feb).
LINK: [link to www.solarham.net
Streamer: [link to iswa.gsfc.nasa.gov
[link to iswa.gsfc.nasa.gov
[link to www.gdgps.net
Active Region Map: [link to sidc.oma.be
STAR Active region map: [link to solen.info
EVE 3-Day: [link to lasp.colorado.edu
Magnetometer: [link to www.swpc.noaa.gov
Ionospheric Electrons: [link to www.ips.gov.au
Ionospheric foF2: [link to www.ips.gov.au
Surface Heat Index (USA)02/04/2013: [link to weather.unisys.com
Sea Surface Temps: [link to www.ssec.wisc.edu
] Estimated Planetary K-Index
: [link to www.solarham.net
3MIN News February 5, 2013: Critical Frequency Update