Posted on by Fraser Cain

Pulsar Blasts Through a Ring of Gas

The radio pulsar PSR B1259-63. Image credit: ESA Click to enlarge
ESA astronomers have witnessed something very unusual; a pulsar crashing through a ring of gas surrounding a companion star. As the pulsar passed through ring, it lit up the area in gamma and X-rays, visible to ESA’s XMM-Newton observatory. This companion star is several times more massive than our own Sun, and rotates so quickly that it’s constantly spewing material out into a ring of gas. The pulsar goes through this ring twice during its 3.4-year elliptical orbit

Astronomers have witnessed a never-seen-before event in observations by ESA’s XMM-Newton spacecraft – a collision between a pulsar and a ring of gas around a neighbouring star.

The rare passage, which took the pulsar plunging into and through this ring, illuminated the sky in gamma- and X-rays.

It has revealed a remarkable new insight into the origin and content of ‘pulsar winds’, which has been a long-standing mystery. The scientists described the event as a natural but ‘scaled-up’ version of the well-known Deep Impact satellite collision with Comet Tempel 1.

Their final analysis is based on a new observation from XMM-Newton and a multitude of archived data which will lead to a better understanding of what drives well-known ‘pulsar nebulae’, such as the colourful Crab and Vela pulsars.

“Despite countless observations, the physics of pulsar winds have remained an enigma,” said lead author Masha Chernyakova, of the Integral Science Data Centre, Versoix, Switzerland.

“Here we had the rare opportunity to see pulsar wind clashing with stellar wind. It is analogous to smashing something open to see what’s inside.”

A pulsar is a fast-spinning core of a collapsed star that was once about 10 to 25 times more massive than our Sun. The dense core contains about a solar mass compacted in a sphere about 20 kilometres across.

The pulsar in this observation, called PSR B1259-63, is a radio pulsar, which means most of the time it emits only radio waves. The binary system lies in the general direction of the Southern Cross about 5000 light-years away.

Pulsar wind comprises material flung away from the pulsar. There is ongoing debate about how energetic the winds are and whether these winds consist of protons or electrons. What Chernyakova’s team has found, although surprising, ties in neatly with other recent observations.

The team observed PSR B1259-63 orbiting a ‘Be’ star named SS 2883, which is bright and visible to amateur astronomers. ‘Be’ stars, so named because of certain spectral characteristics, tend to be a few times more massive than our Sun and rotate at astonishing speeds.

They rotate so fast that their equatorial region bulges and they become flattened spheres. Gas is consistently flung off such a star and settles into an equatorial ring around the star, with an appearance somewhat similar to the planet Saturn and its rings.

The pulsar plunges into the Be star’s ring twice during its 3.4-year elliptical orbit; but the plunges are only a few months apart, just before and after ‘periastron’, the point when the two objects in orbit are closest to each other. It is during the plunges that X-rays and gamma rays are emitted, and XMM-Newton detects the X-rays.

“For most of the 3.4-year orbit, both sources are relatively dim in X-rays and it is not possible to identify characteristics in the pulsar wind,” said co-author Andrii Neronov. “As the two objects draw closer together, sparks begin to fly.”

The new XMM-Newton data was collected nearly simultaneously with a HESS observation. HESS, the High Energy Stereoscopic System, is a new ground-based gamma-ray telescope in Namibia.

Announced last year, the HESS observation was puzzling in that the gamma-ray emission fell to a minimum at periastron and had two maximums, just before and after the periastron, the opposite of what scientists were expecting.

The XMM-Newton observation supports the HESS observation by showing how the maximums were generated by the double plunging into the Be star’s ring. By combining these two observations with radio observations from the last periastron event, the scientists now have a complete picture of this system.

Tracing the rise and fall of X-rays and gamma rays day after day as the pulsar dug through the Be star’s disk, the scientists could conclude that the wind of electrons at an energy level of 10-100 MeV is responsible for the observed X-ray light. (1 MeV represents one million electron volts.)

Although 10-100 MeV is energetic, this is about 1000 times less than the expected energy level of 100 TeV. Even more puzzling is the multi-TeV gamma-ray emission, which, although surely emanating from the 10-100 TeV wind electrons, seems to be produced differently to how it was thought before.

“The only fact that is crystal clear at the moment is that this is the pulsar system to watch if we want to understand pulsar winds,” said Chernyakova.

“Never have we seen pulsar wind in such detail. We are continuing with theoretical models now. We have some good explanation of the radio-to-TeV-gamma-ray behaviour of this funny system, but it is still ‘under construction.'”

Original Source: ESA Portal

Posted on by Fraser Cain

Mimas and Saturn

Mimas captured against its parent planet Saturn. Image credit: NASA/JPL/SSI Click to enlarge
A small and battered reminder of the solar system’s violent youth, the ice moon Mimas hurtles around its gas giant parent, Saturn. At 397 kilometers (247 miles) across, Mimas is simply dwarfed by the immensity of Saturn. The planet is more than 150 times as wide as the moon.

Mimas is seen here against the night side of Saturn. The planet is faintly lit by sunlight reflecting off its rings.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 20, 2006, at a distance of approximately 1.4 million kilometers (900,000 miles) from Mimas and at a Sun-Mimas-spacecraft, or phase, angle of 145 degrees. Image scale is 9 kilometers (5 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Posted on by Fraser Cain

Block Starlight to See Planets

Computed intensity of vortex coronagraph for a single point-like source. Image credit: Grover Swartzlander. Click to enlarge
“Some people say that I study darkness, not optics,” jokes Grover Swartzlander.

But it’s a kind of darkness that will allow astronomers to see the light.

Swartzlander, an associate professor in The University of Arizona College of Optical Sciences, is developing devices that block out dazzling starlight, allowing astronomers to study planets in nearby solar systems.

The devices also may prove valuable to optical microscopy and be used to protect camera and imaging systems from glare.

The core of this technology is an “optical vortex mask” – a thin, tiny, transparent glass chip that is etched with a series of steps in a pattern similar to a spiral staircase.

When light hits the mask dead on, it slows down more in the thicker layers than in thinner ones. Eventually, the light is split and phase shifted so some waves are 180 degrees out of phase with others. The light spins through the mask like wind in a hurricane. When it reaches the “eye” of this optical twister, light waves that are 180 degrees out of phase cancel one another, leaving a totally dark central core.

Swartzlander says this is like light following the threads of a bolt. The pitch of the optical “bolt” – the distance between two adjacent threads – is critical. “We’re creating something special where the pitch should correspond to a change in the phase of one wavelength of light,” he explained. “What we want is a mask that essentially cuts this plane, or sheet, of incoming light and curls it up into a continuous helical beam.”

“What we’ve found recently is knock-your-socks-off amazing from a theoretical point of view,” he added.

“Mathematically, it’s beautiful.”

Optical vortices are not a new idea, Swartzlander noted. But it wasn’t until the mid 1990s that scientists were able to study the physics behind it. That’s when advances in computer-generated holograms and high-precision lithography made such research possible.

Swartzlander and his graduate students, Gregory Foo and David Palacios, garnered media attention recently when “Optics Letters” published their article on how optical vortex masks might be used on powerful telescopes. The masks could be used to block starlight and allow astronomers to directly detect light from a 10-billion-times-dimmer planet orbiting the star.

This could be done with an “optical vortex coronagraph.” In a traditional coronagraph, an opaque disk is used to block a star’s light. But astronomers who are searching for faint planets near bright stars can’t use the traditional coronagraph because glare from starlight diffracts around the disk obscuring light reflected from the planet.

“Any small amount of diffracted light from the star is still going to overwhelm the signal from the planet,” Swartzlander explained. “But if the spiral of the vortex mask coincides exactly with the center of the star, the mask creates a black hole where there is no scattered light, and you’d see any planet off to the side.”

The UA team, which also included Eric Christensen from UA’s Lunar and Planetary Lab, demonstrated a prototype optical vortex coronagraph on Steward Observatory’s 60-inch Mount Lemmon telescope two years ago. They couldn’t search for planets outside our solar system because the 60-inch telescope isn’t equipped with adaptive optics that corrects for atmospheric turbulence.

Instead, the team took pictures of Saturn and its rings to demonstrate how easily such a mask could be used with a telescope’s existing camera system. A photo from the test is online at Swartzlander’s website, http://www.u.arizona.edu/~grovers.

Optical vortex coronagraphs could be valuable to future space telescopes, such as NASA’s Terrestrial Planet Finder (TPF) and the European Space Agency’s Darwin mission, Swartzlander noted. The TPF mission will use space-based telescopes to measure the size, temperature, and placement of planets as small as the Earth in the habitable areas of distant solar systems.

“We’re applying for grants to make a better mask – to really ramp this thing up to get better quality optics, Swartzlander said. “We can demonstrate this now in the lab for laser beams, but we need a really good-quality mask to get closer to what’s needed for a telescope.”

The big challenge is developing a way to etch the mask to get “a big fat zero of light” at its core, he said.

Swartzlander and his graduate students are doing numerical simulations to determine the proper pitch for helical masks at the desired optical wavelengths. Swartzlander has filed a patent for a mask that covers more than one wavelength, or color of light.

The U.S. Army Research Office and State of Arizona Proposition 301 funds support this research.

The Army Research Office funds basic optical sciences research, although Swartzlander’s work also has practical defense applications.

Optical vortex masks also could be used in microscopy to enhance the contrast between biological tissues.

Original Source: UA News Release

Posted on by Fraser Cain

CryoSat-2 Will be Constructed

First CryoSat satellite during launch campaign. Image credit: ESA Click to enlarge
At the latest meeting of the European Space Agency’s Earth Observation Programme Board, which took place at ESA’s Headquarters in Paris on 23 and 24 February, ESA received the green light from its Member States to build and launch a CryoSat recovery mission, CryoSat-2.

The launch of the CryoSat spacecraft was unfortunately aborted on 8 October 2005 due to a malfunction of its Rockot launcher, which resulted in the total loss of the spacecraft.

“This decision is very important, as the scientific community in Europe and elsewhere is eagerly awaiting resumption of the CryoSat mission. We are happy to have obtained approval today”, said Volker Liebig, ESA Director of Earth observation programmes.

A CryoSat recovery plan was presented to the Programme Board by ESA’s Executive, which explained the status of ongoing activities and outlined the preparatory work leading to a CryoSat-2 mission, expected to be launched in March 2009.

CryoSat-2 will have the same mission objectives as the original CryoSat mission; it will monitor the thickness of land ice and sea ice and help explain the connection between the melting of the polar ice and the rise in sea levels and how this is contributing to climate change.

The positive decision on CryoSat-2 will allow rational use to be made of the technical and industrial competences for the original mission, as well as best use of the ground segment facilities and operational setup planned for that first mission. It means that the pre-launch scientific validation campaigns over land ice and sea ice can resume with the support of national institutes.

Original Source: ESA Portal

Posted on by Fraser Cain

What’s Inside a Gas Giant?

Cutaway of Jupiter. Credit: Kevinsong

University of Minnesota researchers Renata Wentzcovitch and Koichiro Umemoto and Philip B. Allen of Stony Brook University have modeled the properties of rocks at the temperatures and pressures likely to exist at the cores of Jupiter, Saturn and two exoplanets far from the solar system. They show that rocks in these environments are different from those on Earth and have metallic-like electric and thermal conductivity. These properties can produce different terrestrial-type planets, with longer-lasting magnetic fields, enhanced heat flow to the planetary surfaces and, consequently, more intense “planetquake” and volcanic activity.

This work builds on the authors’ recent work on Earth’s inner layers and represents a step toward understanding how all planets, including Earth, come to acquire their individual characteristics. The research is published in the Feb. 17 issue of Science. In the previous work, Wentzcovitch and her colleagues studied the D” (“Dee double prime”) layer deep in the Earth.

D” runs from zero to 186 miles thick and surrounds the iron core of our planet. It lies just below Earth’s mantle, which is largely composed of a mineral called perovskite, consisting of magnesium, silicon and oxygen. Wentzcovitch and her team calculated that in D” the great temperatures and pressures changed the structure of perovskite crystals, transforming the mineral into one called “post-perovskite.”

In the new work, the researchers turned their attention to the cores of the giant planets of our solar system – Jupiter, Saturn, Uranus and Neptune – and two recently discovered extrasolar planets, or exoplanets, found elsewhere in the Milky Way. One, referred to as Super-Earth, is about seven times the mass of Earth and orbits a star 15 light-years away in the constellation Aquarius. The other, Dense-Saturn, has about the same mass as Saturn and orbits a star 257 light-years away in the constellation Hercules.

The researchers calculated what would happen at temperatures and pressures likely near the cores of the two exoplanets, Jupiter and Saturn, where temperatures run close to 18,000 F and pressures 10 million bars (a bar is essentially atmospheric pressure at sea level). They found that even post-perovskite could not withstand such conditions, and its crystals would dissociate into two new forms. Focusing on one of those crystals, the researchers discovered that they would behave almost like metals.

That is, electrons in the crystals would be very mobile and carry electric current. This would have the effect of supporting the planet’s magnetic field (if it has one) and inhibiting reversals of the field. The increased electrical activity would also help transport energy out of the core and toward the planet surface. This could result in more severe activities such as quakes and volcanoes on the surface. The effect would be much stronger in Dense-Saturn than in Super-Earth.

The interiors of the icy giants Uranus and Neptune don’t exhibit such extremes of temperature and pressure, and so post-perovskite would survive in their cores, she said. “We want to understand how planets formed and evolved and how they are today. We need to understand how their interiors behave under these extreme pressure and temperatures conditions. Only then it will be possible to model them. This will advance the field of comparative planetology,” said Wentzcovitch. “We will understand Earth better if we can see it in the context of a variety of different kinds of planets.”

Posted on by Fraser Cain

FUSE Satellite is Working Again

FUSE lift off in 1999. Image credit: NASA/KSC Click to enlarge
NASA’s Far Ultraviolet Spectroscopic Explorer astronomy satellite is back in full operation, its aging onboard software control system rejuvenated and its mission extended by enterprising scientists and engineers after a near-death experience in December 2004.

Observations with the orbiting telescope resumed Nov. 1, 2005, about ten months after the third of four onboard reaction wheels, used to precisely point the spacecraft and hold it steady, stopped spinning. After two months of experience tweaking the new control system in November and December, FUSE operations returned in January to a level of efficiency comparable to earlier in the mission, mission managers said.

“It’s really a level of performance that we never thought we would see again,” said William Blair (pictured at right), a research professor in physics and astronomy at Johns Hopkins and FUSE’s chief of observatory operations. “The old satellite still has some spunk.”

FUSE was launched in June 1999. Late in 2001, two of the reaction wheels failed in quick succession, leaving the satellite temporarily unusable. That time, science operations were successfully resumed within about two months through a modification of flight control software and development of a creative new technique to establish fine pointing control.

“The project aggressively pursued a similar track this time, but it was even harder with just one operational reaction wheel,” said George Sonneborn, FUSE project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “Some people would say what we’re doing is nearly impossible.”

Initially, at least three reaction wheels were required for the spacecraft to conduct its scientific mission. The revised control mode developed in 2001 utilized the two remaining reaction wheels and drafted the satellite’s magnetic torquer bars into the effort to provide control in all three axes. The MTBs (essentially, controllable electromagnets) apply forces on the satellite by interacting with Earth’s magnetic field. Now, the FUSE control system has been modified again to use magnetic control on two axes, which provides a tenuous but acceptable level of control in place of the missing reaction wheels.

“It’s like we had three strong muscles originally, and could point FUSE wherever we wanted to,” Blair said. “Now we have to control the pointing with one strong muscle and two weak muscles. The revised control software is like a good physical therapist, teaching the satellite to compensate.”

Since its launch, FUSE has obtained more than 52 million seconds of science data on everything from planets and comets in our solar system to distant quasars and active galaxies, and every major class of object in between. This information, compiled in the form of spectrographs rather than visual images, provides astronomers with details about the physical properties and characteristics of objects, from temperatures and densities to chemical makeup.

Observations from the satellite have been used to discover an extended, tenuous halo of very hot gas surrounding our Milky Way galaxy, and have found evidence of similar hot gas haloes around other galaxies. FUSE has also detected molecular hydrogen in the atmosphere of the planet Mars for the first time. This has implications for the water history of our frozen neighbor. In addition, FUSE observations first detected molecular nitrogen in dense interstellar gas and dust clouds, but at levels well below what astronomers had expected, requiring a return to the drawing board for theories of interstellar chemistry.

NASA has twice extended what originally was planned as FUSE’s three-year mission to carry out a broad range of science programs for hundreds of astronomers from around the world. To date, more than 350 publications based on FUSE observations have been published in the professional astronomy literature and many more are on the way. A new set of planned observations for the coming year was accepted in December 2005 by NASA, and the first of these has already been obtained.

“The recovery of FUSE operations is a tremendous testament to the dedication and ingenuity of the scientists and engineers at Johns Hopkins and at the Orbital Sciences Corp.,” said Warren Moos, professor of physics and astronomy and principal investigator for FUSE. “There are a large number of astronomers in line waiting for FUSE observations that are now being undertaken once again.”

The Johns Hopkins University has primary responsibility for all aspects of FUSE, including both the development and operational phases of the mission. The FUSE science and satellite control center is on the Johns Hopkins Homewood campus in Baltimore. FUSE partners include Honeywell Technical Services Inc., the Johns Hopkins Applied Physics Laboratory, the Canadian Space Agency, the French Space Agency, the University of Colorado at Boulder, and the University of California, Berkeley, in addition to Orbital Sciences Corporation.

FUSE is a NASA Explorer mission. Goddard Space Flight Center manages the Explorers Program for NASA Headquarters in Washington, D.C.

For more on the FUSE mission and future status updates, visit the FUSE website at fuse.pha.jhu.edu.

Original Source: JHU News Release

Posted on by Fraser Cain

Astrophoto: A New Star in Ophiucus by John Chumack

RS Ophicuchi by John Chumack
On February 12, Universal time, two Japanese observers, Kiyotaka Kanai and Hiroaki Narumi, noticed that a star normally too dim to be seen by the unaided eye in the constellation of Ophiucus had suddenly grown much brighter. It was now about as visible as the star in the handle of the Little Dipper that is nearest Polaris, the northern pole star. The star is named RS Ophicuchi and it has done this before in 1898, 1933, 1945 (this date is suspected), 1958, 1967 and 1985.

RS Ophicuchi is a double star – one’s a red giant the other’s a white dwarf. Material from the red giant is constantly being pulled toward the dwarf where it accumulates to form a flat, ring-like disk that reaches to its surface. Over time the pressure within and temperature of the accretion disk increases until it’s enough to ignite a thermonuclear explosion of unimaginable proportions. We see that flash of brilliance, this one was located three thousand light years in the distance, as a nova.

Novas only happen in stellar pairs and represent the aches and pains of older stars. Unlike supernova, which occur in single, massive stars, novas seldom result in the annihilation of either.

As of last weekend, the brilliance of the nova had started to fade and will continue to do so gradually for quite some time. During the 1985 episode, it took almost a year and a half before the stars had returned to their normal faintness as seen here on Earth. Of course, now that the previous material has been destroyed, new material will slowly start to re-accumulate on the dwarf star and begin a new cycle that will lead up to the next explosion.

John Chumack took this picture of RS Ophicuchi, three days after its discovery from a remotely controlled observatory in New Mexico. John took sixteen 30 second pictures then combined them to create this full color image that is the equivalent of a single eight minute exposure. This image covers a sky area that is approximately four full moons wide using a Takahashi Sky90 telescope and a SBIG three mega-pixel camera.

Do you have photos you’d like to share? Post them to the Universe Today astrophotography forum or email them, and we might feature one in Universe Today.

Written by R. Jay GaBany

Posted on by Fraser Cain

What’s Up This Week – February 27 – March 5, 2006

What's Up 2006

Download our free “What’s Up 2006” ebook, with entries like this for every day of the year.

AE Aurigaey. Image credit: T.A. Rector and B.A. Wolpa/NOAO/AURA/NSF. Click to enlarge.
UPDATE: Comet Pojmansk is in the observing news! Now rounding the Sun, it will make its nearest approach to Earth on March 5. At the beginning of the week it averages a magnitude approaching 7 and is brightening fast – possibly coming within unaided viewing range within days. By Monday morning it should reach visiblity for the northern hemisphere and reach a maximum elongation of 22 degrees. Check out a map from SkyHound and be on the lookout!!

Monday, February 27 – Today is the birthday of Bernard Lyot. Born in 1897, Lyot went on to become the inventor of the coronagraph in 1930. Although we cannot hand you a corona, we can show you a star that wears its own gaseous envelope.

Let’s go to our maps west of M36 and M38 to identify AE Aurigae. As an unusual variable, AE is normally around 6th magnitude and resides approximately 1600 light years distant. The beauty in this region is not particularly the star itself but the faint nebula in which it resides known as IC 405, an area of mostly dust and very little gas. What makes this view so entertaining is that we are looking at a “runaway” star. It is believed that AE once originated from the M42 region in Orion. Cruising along at a very respectable speed of 80 miles per second, AE flew the “stellar nest” some 2.7 million years ago! Although IC 405 is not directly related to AE, there is evidence within the nebula that areas have been cleared of their dust by the rapid northward motion of the star. AE’s hot, blue illumination and high energy photons fuel what little gas is contained within the region. Its light also reflects off the surrounding dust. Although we cannot “see” with our eyes like a photograph, together the pair forms an outstanding view for the small backyard telescope and it is known as “The Flaming Star.”

Tuesday, February 28 – Are you ready for a New Moon challenge? Then take advantage of dark sky time to head toward Orion. Tonight our aim is toward a single star – but there is much more hiding there than just a point of light!

Our first stop is the eastern-most star in the “belt,” Zeta Orionis, or better known as Alnitak. At a distance of some 1600 light years, this 1.7 magnitude beauty contains many surprises ? it’s a double star system. High power and steady skies are needed to make Alnitak’s duplicity clear, but if you want more, look a breath east and revisit the Flame Nebula – a fantastic field of nebulosity illuminated by Alnitak. The NGC 2024 is an outstanding region of nebulosity spread over an area the apparent size of a full moon.

Still not enough? Break out the big scope and put Zeta out of the field of view to the north at high power and allow your eyes to re-adjust. When you look again, you will see a long, faded ribbon of nebulosity called IC 434 south of Zeta. It stretches over a degree toward the south. The eastern edge of the “ribbon” is very bright and mists away to the west. Now hold your breath and look almost directly in the center. See that dark notch with two faint stars south of it? You have located one of the most famous of the Barnard dark nebulae – B33.

You may exhale now. B33 is also known as the “Horsehead Nebula.” This “Horsehead” is very tough visually – the classic chess piece appearance of a “knight” is only fully appreciated in photographs – but those of you who have large aperture can see a dark “notch,” improved with the use of a specific nebula filter. B33 is a small area cosmically, only about one light year in expanse. It’s nothing more than obscuring dark dust and non-luminous gas – but what an incredible shape! If you do not succeed at first attempt, try again. The “Horsehead” is one of the most challenging objects in the sky and has been observed with apertures as small as 150mm. This just might be your lucky “Knight”?

Wednesday, March 1 – George Abell was born this day in 1927. Abell cataloged 2712 clusters of galaxies based on the Palomar sky survey completed in 1958. Using plates taken by the 48-inch Oschin Schmidt telescope, Abell put forth the idea that the grouping of galaxy clusters related to the overall arrangement of matter in the universe. He developed the “luminosity function” – correlating brightness and number of members in clusters with distance. Abell also discovered a number of planetary nebulae and developed, along with Peter Goldreich, the theory of planetary evolution from red giants.

With the moon out of the picture early, why not get caught up in a galaxy cluster study – Abell 426. Located just 2 degrees east of Algol in Perseus, this group of 233 galaxies spread over a region of several degrees of sky is easy enough to find – but difficult to observe. Spotting Abell galaxies in Perseus can be tough in smaller instruments, but those with large aperture scopes will find it worthy of time and attention.

At magnitude 11.6, NGC 1275 is the brightest of the group and lies physically near the core of the cluster. Glimpsed in scopes as small as 150 mm aperture, NGC 1275 is a strong radio source and an active site of rapid star formation. Images of the galaxy show a strange blend of a perfect spiral being shattered by mottled turbulence. For this reason NGC 1275 is thought to be two galaxies in collision.
Depending on seeing conditions and aperture, galaxy cluster Abell 426 may reveal anywhere from 10 to 24 small galaxies as faint as magnitude 15. The core of the cluster is more than 200 million light-years away, so it’s an achievement to spot even a few!

Thursday, March 2 – Tonight the Moon appears as a very slender crescent setting to the west in Pisces. This lunar apparition looks very much like a pair of bright horns bearing a dark disk. Such a moon may have given rise to the ancient symbol associated with fertility goddesses originating in Egypt and Mesopotamia. Today we see it “as the old moon in the new moon’s arms.” To see this lunar phase is an Astronomical League challenge.

Skies darken early again tonight, so we’ll have a look at an open cluster easily seen in binoculars and well resolved in small scopes. Start at bright Castor and Pollux in Gemini and turn your eyes, binoculars, or finder scope almost due south to even brighter Procyon. Drop almost the same distance to Xi Puppis. Once you locate Xi, shift the scope or binoculars roughly one finger-width (two degrees) northwest. There you will see a hazy rectangular patch with a handful of barely resolvable stars in its midst – the open cluster M93.

First cataloged by Charles Messier in March of 1781, this wonderfully bright grouping contains a broad range of stellar types among its 80 or so members. Even at a distance of 3500 light-years, binoculars reveal the cluster’s bright haze and sharply angular swatch of core stars and a scope will resolve it. Towards the center, a wedge-shaped collection of bright members congregate. At the heart of the wedge is an easy double star – with another echoing the pair to the west. The very brightest of these stars are young, hot, and blue with an overall stellar population similar to the Pleiades. How old you ask? A very young one million years.

Friday, March 3 – With the Moon near the horizon, we have only a short time to view its features. Tonight let’s start with a central feature – Langrenus – and continue further south for crater Vendelinus. Spanning 92 by 100 miles and dropping 14,700 feet below the lunar surface, Vendelinus displays a partially dark floor with a west wall crest catching the brilliant light of an early sunrise. Notice also that its northeast wall is broken by a younger crater – Lame. Head’s up! It’s an Astronomical League challenge.

Once the Moon has set, revisit M46 in Puppis – along with its mysterious planetary nebula NGC 2438. Follow up with a visit to neighboring open cluster M47 – two degrees west-northwest. M47 may actually seem quite familiar to you already. Did you possibly encounter it when originally looking for M46? If so, then it’s also possible that you met up with 6.7 magnitude open cluster NGC 2423, about a degree northeast of M47 and even dimmer 7.9 magnitude NGC 2414 as well. That’s four open clusters and a planetary nebula all within four square arc-minutes of sky. That makes this a cluster of clusters!

Let’s return to study M47. Observers with binoculars or using a finderscope will notice how much brighter, and fewer, the stars of M47 are when compared to M46. This 12 light-year diameter compact cluster is only 1600 light-years away. Even as close as it is, not more than 50 member stars have been identified. M47 has about one tenth the stellar population of larger, denser, and three times more distant, M46.

Of historical interest, M47 was “discovered” three times: first by Giovanni Batista Hodierna in the mid-17th century, then by Charles Messier some 17 years later, and finally by William Herschel 14 years after that. How is it possible that such a bright and well-placed cluster needed “re-discovery?” Hodierna’s book of observations didn’t surface until 1984, and Messier gave the cluster’s declination the wrong sign, making its identification an enigma to later observers – because no such cluster could be found where Messier said it was!

Saturday, March 4 Born on this date in 1835, Giovanni Schiaparelli opened his eyes (and later ours) to a new world of possibilities – life on Mars. As director of Milan Observatory in 1877, Schiaparelli first described fine, faint features on the surface of Mars as “canali.” Perhaps one of Schiaparelli’s most important contributions was making the connection between meteor streams and the comets that produced them.

Tonight let’s return to our studies of the Moon and a more challenging crater. Further south than Vendelinus, look for another large, mountain-walled plain named Furnerius not too far from the terminator. Although it has no central peak, its walls have been broken numerous times by many smaller impacts. Look at a rather large one just north of central on the crater floor. If skies are stable, power up and search for a rima extending from the northern edge. Keep in mind as you observe that our own Earth has been pummeled just as badly as its satellite.

Sunday, March 5 – Today is the 494th anniversary of Gerardus Mercator’s birth in 1512. The famed mapmaker went on to live a life of great moral courage. Mercator’s time was a rough one for astronomy and astronomers. Despite a prison sentence and threats of torture and death for his “beliefs,” Mercator went on to design a globe of the earth in 1541 and one for the heavens ten years later. One sphere within a larger one – and all without the many complexities envisioned by Ptolemy a millennium before him.

Tonight the Moon provides an opportunity to view to a very changeable and eventually bright feature on the lunar surface – Proclus. At 28 km in diameter and 2400 meters deep, crater Proclus will appear on the terminator to the west of Mare Crisium’s mountainous border. Depending on your viewing time, it will seem to be about two-thirds shadowed, but the remainder of the crater will shine brilliantly. Proclus has an unusually high albedo, or surface reflectivity, of about 16%. This is uncommon for most lunar features. Watch this area over the next few nights as two rays from the crater widen and lengthen, extending approximately 320 kilometers north and south.

Now, just look at the Moon. Can you spot the Pleiades nearby?

Now let’s have a go at the dense open cluster NGC 2301. Located about two finger-widths northwest of visual double Delta Monoceros, this 6th magnitude cluster can be seen in binoculars as a small, faint haze divided by a line of barely resolved stars. Telescopes will reveal a half dozen bright stellar members, plus a number of small clumps of dimmer stars.

Keep rockin’ the night and may all your journeys be at light speed! ….~Tammy Plotner with additional writing by Jeff Barbour @ astro.geekjoy.com

Posted on by Fraser Cain

NASA’s Orbiter is Almost at Mars

Artist’s concept of Mars Reconnaissance Orbiter approaching Mars. Image credit: NASA/JPL Click to enlarge
As it nears Mars on March 10, a NASA spacecraft designed to examine the red planet in unprecedented detail from low orbit will point its main thrusters forward, then fire them to slow itself enough for Mars’ gravity to grab it into orbit.

Ground controllers for Mars Reconnaissance Orbiter expect a signal shortly after 1:24 p.m. Pacific time (4:24 p.m. Eastern time) that this mission-critical engine burn has begun. However, the burn will end during a suspenseful half hour with the spacecraft behind Mars and out of radio contact.

“This mission will greatly expand our scientific understanding of Mars, pave the way for our next robotic missions later in this decade, and help us prepare for sending humans to Mars,” said Doug McCuistion, Director of NASA’s Mars Exploration Program. “Not only will Mars Science Laboratory’s landing and research areas be determined by the Mars Reconnaissance Orbiter, but the first boots on Mars will probably get dusty at one of the many potential landing sites this orbiter will inspect all over the planet.”

The orbiter carries six instruments for studying every level of Mars from underground layers to the top of the atmosphere. Among them, the most powerful telescopic camera ever sent to a foreign planet will reveal rocks the size of a small desk. An advanced mineral-mapper will be able to identify water-related deposits in areas as small as a baseball infield. Radar will probe for buried ice and water. A weather camera will monitor the entire planet daily. An infrared sounder will monitor atmospheric temperatures and the movement of water vapor.

The instruments will produce torrents of data. The orbiter can pour data to Earth at about 10 times the rate of any previous Mars mission, using a dish antenna 3 meters (10 feet) in diameter and a transmitter powered by 9.5 square meters (102 square feet) of solar cells. “This spacecraft will return more data than all previous Mars missions combined,” said Jim Graf, project manager for Mars Reconnaissance Orbiter at NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

Scientists will analyze the information to gain a better understanding of changes in Mars’ atmosphere and the processes that have formed and modified the planet’s surface. “We’re especially interested in water, whether it’s ice, liquid or vapor,” said JPL’s Dr. Richard Zurek, project scientist for the orbiter. “Learning more about where the water is today and where it was in the past will also guide future studies about whether Mars has ever supported life.”

A second major job for Mars Reconnaissance Orbiter, in addition to its own investigation of Mars, is to relay information from missions working on the surface of the planet. During its planned five-year prime mission, it will support the Phoenix Mars Scout, which is being built to land on icy soils near the northern polar ice cap in 2008, and the Mars Science Laboratory, an advanced rover under development for launch in 2009.

However, before Mars Reconnaissance Orbiter can begin its main assignments, it will spend half a year adjusting its orbit with an adventurous process called aerobraking. The initial capture by Mars’ gravity on March 10 will put the spacecraft into a very elongated, 35-hour orbit. The planned orbit for science observations is a low-altitude, nearly circular, two-hour loop. To go directly into an orbit like that when arriving at Mars would have required carrying much more fuel for the main thrusters, requiring a larger and more expensive launch vehicle and leaving less payload weight for science instruments. Aerobraking will use hundreds of carefully calculated dips into the upper atmosphere — deep enough to slow the spacecraft by atmospheric drag, but not deep enough to overheat the orbiter.

“Aerobraking is like a high-wire act in open air,” Graf said. “Mars’ atmosphere can swell rapidly, so we need to monitor it closely to keep the orbiter at an altitude that is effective but safe.” Current orbiters at Mars will provide a daily watch of the lower atmosphere, an important example of the cooperative activities between missions at Mars.

Additional information about Mars Reconnaissance Orbiter is available online at:

http://www.nasa.gov/mro

The mission is managed by JPL, a division of the California Institute of Technology, Pasadena, for the NASA Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft.

Original Source: NASA News Release

Posted on by Fraser Cain

Swift Sees an Unusual Gamma Ray Burst

The strange cosmic explosion that occured on February 18th. Image credit: SDSS/Swift Click to enlarge
The Swift satellite, whose mission control center is in State College, has detected a cosmic explosion that has sent scientists around the world scrambling to telescopes to document this startling event. Gamma-ray radiation from the source, detected on 18 February and lasting about half an hour, appears to be a precursor to a supernova, which is the death throes of a star much more massive than the Sun. “The observations indicate that this is an incredibly rare glimpse of an initial gamma-ray burst at the beginning of a supernova,” said Peter Brown, a Penn State graduate student and a member of the Swift science team.

Astronomers are using Swift, whose science and flight operations are controlled by Penn State from the Mission Operations Center in State College, to continue to observe the event. Scores of satellites and ground-based telescopes also are now trained on the sight, watching and waiting. Amateur astronomers in the northern hemisphere with a good telescope in dark skies also can view the source.

The explosion has the trappings of a gamma-ray burst, the most distant and powerful type of explosion known. This event, however, was about 25 times closer and 100 times longer than the typical gamma-ray burst. “This burst is totally new and unexpected,” said Neil Gehrels, Swift principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “This is the type of unscripted event in our nearby universe that we hoped Swift could catch.”

The explosion, called GRB 060218 after the date it was discovered, originated in a star-forming galaxy about 440 million light-years away toward the constellation Aries. This is the second-closest gamma-ray burst ever detected, if indeed it is a true burst.

Derek Fox, assistant professor of astronomy and astrophysics at Penn State, who is leading the monitoring effort of GRB 060218 on the Hobby-Eberly Telescope, commented, “This is the burst we’ve been waiting eight years for,” referring to the closest-ever gamma-ray burst, which was detected in 1998. “The special capabilities of Swift, which was not operating in 1998, combined with the intense campaign of ground-based telescopes, should help unravel this mystery,” said Fox.

“There are still many unknowns,” said Penn State Professor of Astronomy and Astrophysics John Nousek, the Swift mission operations director at Penn State University in University Park, Pennsylvania. The burst of gamma rays lasted for nearly 2,000 seconds; in contrast, most such bursts last a few milliseconds to tens of seconds. The explosion also was surprisingly dim. “This could be a new kind of burst, or we might be seeing a gamma-ray burst from an entirely different angle,” he said. The standard theory for gamma-ray bursts is that the high-energy light is beamed in our direction. “This off-angle glance–a profile view, perhaps–has given us an entirely new approach to studying star explosions. Had this burst been farther away, we would have missed it,” Nousek explained.

Because the burst was so long, Swift was able to observe the bulk of the explosion with all three of its instruments: the Burst Alert Telescope, which detected the burst; and the X-ray Telescope, and Ultraviolet/Optical Telescope, which provide high-resolution imagery and spectra across a broad range of wavelengths. Penn State lead the development of the X-ray and Ultraviolet/Optical Telescopes.

Scientists will attempt observations with the Hubble Space Telescope and the Chandra X-ray Observatory. Amateur astronomers in dark skies might be able to see the explosion with a 16-inch telescope as it hits 16th-magnitude brightness.

Swift is a NASA mission in partnership with the Italian Space Agency and the Particle Physics and Astronomy Research Council in the United Kingdom; it is managed by NASA Goddard, and Penn State controls its science and flight operations from the Mission Operations Center in University Park, Pennsylvania.

PSU News Release