It was a slow week on Space news except for the massive announcement that an ancient riverbed was discovered on the surface of Mars. We took a look at this as well as the historic 55th anniversary of Sputnik, a precise measurement of the expansion of the Universe, and more!
Swift J1745-26, with a scale of the moon as it would appear in the field of view from Earth. This image is from September 18, 2012 when the source peaked in hard X-rays. Credit: NASA/Goddard Space Flight Center/S. Immler and H. Krimm
Back in mid-September, the Swift satellite was going about its multi-wavelength business of watching for bursts of bright gamma-ray, X-ray, ultraviolet, or optical events in the sky, when it detected a rising tide of high-energy X-rays from a source toward the center of our Milky Way galaxy. But this was different from any other burst the satellite had detected, and after observing the event for a few days, astronomers knew this had to be a rare X-ray nova. What it meant was that Swift had detected the presence of a previously unknown stellar-mass black hole.
“Bright X-ray novae are so rare that they’re essentially once-a-mission events and this is the first one Swift has seen,” said Neil Gehrels from Goddard Space Flight Center, the mission’s principal investigator. “This is really something we’ve been waiting for.”
The object was named Swift J1745-26 after the coordinates of its sky position, the nova is located a few degrees from the center of our galaxy toward the constellation Sagittarius. While astronomers do not know its precise distance, they think the object resides about 20,000 to 30,000 light-years away in the galaxy’s inner region.
An X-ray nova is a short-lived X-ray source that appears suddenly in the sky and dramatically increases in strength over a period of a few days and then decreases, fading out over a few months. Unlike a conventional nova, where the compact component is a white dwarf, an X-ray nova is caused by material – usually gas — falling onto a neutron star or a black hole.
The rapidly brightening source triggered Swift’s Burst Alert Telescope twice on the morning of Sept. 16, and once again the next day.
Ground-based observatories detected infrared and radio emissions, but thick clouds of obscuring dust have prevented astronomers from catching Swift J1745-26 in visible light.
The nova peaked in hard X-rays — energies above 10,000 electron volts, or several thousand times that of visible light — on Sept. 18, when it reached an intensity equivalent to that of the famous Crab Nebula, a supernova remnant that serves as a calibration target for high-energy observatories and is considered one of the brightest sources beyond the solar system at these energies.
Even as it dimmed at higher energies, the nova brightened in the lower-energy, or softer, emissions detected by Swift’s X-ray Telescope, a behavior typical of X-ray novae. By Wednesday, Swift J1745-26 was 30 times brighter in soft X-rays than when it was discovered and it continued to brighten.
“The pattern we’re seeing is observed in X-ray novae where the central object is a black hole. Once the X-rays fade away, we hope to measure its mass and confirm its black hole status,” said Boris Sbarufatti, an astrophysicist at Brera Observatory in Milan, Italy, who currently is working with other Swift team members at Penn State in University Park, Pa.
Here’s usually happens in events like this: The black hole is part of a binary system with a normal Sun-like star. A stream of material flows into an accretion disk around the black hole. Usually, the disk of gas spirals in steadily to the black hole, heats up and produces a steady X-ray glow. But sometimes, for reasons unknown, the material is held up in the outer regions, held back by some mechanism, almost like a dam. Once enough gas accumulates, the dam breaks and a flood of gas surges towards the black hole, creating the X-ray nova outburst.
“Each outburst clears out the inner disk, and with little or no matter falling toward the black hole, the system ceases to be a bright source of X-rays,” said John Cannizzo, a Goddard astrophysicist. “Decades later, after enough gas has accumulated in the outer disk, it switches again to its hot state and sends a deluge of gas toward the black hole, resulting in a new X-ray outburst.”
This phenomenon, called the thermal-viscous limit cycle, helps astronomers explain transient outbursts across a wide range of systems, from protoplanetary disks around young stars, to dwarf novae — where the central object is a white dwarf star — and even bright emission from supermassive black holes in the hearts of distant galaxies.
It is estimated that our galaxy must harbor some 100 million stellar-mass black holes. Most of these are invisible to us, and only about a dozen have been identified.
Swift discovers about 100 bursts per year. The Burst Alert Telescope detects GRBs and other events and accurately determines their positions on the sky. Swift then relays a 3 arcminute position estimate to the ground within 20 seconds of the initial detection, enabling ground-based observatories and other space observatories the chance to observe the event as well. The Swift spacecraft itself “swiftly” –in less than approximately 90 seconds — and autonomously repoints itself to bring the burst location within the field of view of the sensitive narrow-field X-ray and UV/optical telescopes to observe the afterglow and gather data.
Emperor Penguins on the Antarctic Sea Ice Under the Aurora Australis. Credit and copyright: Stefan Christmann. Used by permission.
Photographer Stefan Christmann called this incredible Antarctic view a once in a lifetime experience.
“It was the most impressive experience to sit on the sea-ice and watch the Aurora Australis dance above the penguin colony with the sounds of the chicks and the adult penguins. I feel truly blessed for having had the opportunity to witness this once in a lifetime experience,” he told Universe Today.
Christmann is currently based in Antarctica, working at the German Antarctic research station Neumayer III. He is an “overwinterer” — scientific and technical staff who stay at the base for the entire southern winter — and will stay in Antarctica for an uninterrupted 14 months. “As a physicist, my duty is to maintain the data acquisition of our seismological and geomagnetic observatories as well as the analysis of the collected data,” Christmann said.
But he is also an accomplished photographer. His website and Facebook page are filled with beautiful nature images from around the world, and recently feature the Emperor penguins and their adorable chicks, as well as the stark beauty of the Antarctic landscape.
Originally from Germany, he studied photography in the US, and his work has now brought him to an extended stay in Antarctica.
Christmann explained the conditions and the difficulties in obtaining this shot, one he had long hoped for, the planning of it always in the back of his mind.
“The picture was taken at Atka-Bay on the sea-ice. The bay is roughly 8 km away from our station so the penguin colony is a popular destination for free-time trips. The idea of a photo of the Aurora Australis above the penguin colony had been in my head for a long time, but the conditions have to be just right –which usually never happens. You need a full Moon, high magnetic activity and a cloudless sky. Also the penguins should be standing close enough to the ice-berg. I made multiple attempts to get the photo, but we either had incoming clouds, low activity or had to cancel our stay because of wind picking up (which can be really dangerous out on the sea-ice).”
And time was short, as after he had been outside for a few hours the wind picked up and he and his accomplices had to leave the ice for safety reasons. “Otherwise we probably would have sat there all night!” Christmann said. The image was taken on October 1, 2012.
Christmann shared what equipment he uses as well as a few tips for Antarctic and cold weather photography.
“I used a Nikon D700 Fullframe DSLR with an AF-S G-Nikkor 14-24mm f/2.8. ISO settings varied with the intensity of the aurora from ISO 500-800,” he said. “F-Stops in the range of 4.0-5.6 and Exposure times from 20s to 30s. I try to keep ISO as low as possible for noise reasons and also try to limit the exposure time in order not to get star trails. It’s either super long star trails or almost star-dots, but I don’t really like the in between. A full battery charge (in my case around 2500mAh) lasts around 1h in the cold, so I had to switch batteries twice during our stay out on the ice!”
Asked what other details he felt was important to share about this image, Christmann said, “Antarctica is an incredible place where nature dwarfs anything made by humans. Hopefully people will gain even more interest in this continent and help to protect it as well as its inhabitants.”
To see more of Christmann’s work visit his website, Nature in Focus or his Facebook page, where he shares many pictures of his Antarctic adventure.
Please note: This image may not be re-posted, used or copied without the express permission of Stefan Christmann.
Astronomers have known for some time there was one star orbiting fairly close to the black hole at the center of our galaxy. But now another star has been found dipping close and orbiting even faster around the Milky Way’s central black hole. Astronomer Andrea Ghez from UCLA says the ability to watch these two stars in a short-period ‘tango’ around the black hole will help scientist measure the effects of space-time curvature, and they should be able to determine whether Albert Einstein was right in his prediction of how black holes could warp space and time.
“I’m extremely pleased to find two stars that orbit our galaxy’s supermassive black hole in much less than a human lifetime,” said Ghez. “It is the tango of [these stars] that will reveal the true geometry of space and time near a black hole for the first time. This measurement cannot be done with one star alone.”
There are nearly 3,000 stars that orbit somewhat close to the black hole, and most of them have orbits of 60 years or longer.
The previously known close-in star, S0-2, orbits the black hole every 15.5 years. And now, the newly found star, called S0-102, orbits the black hole in a blazing 11.5 years, the shortest known orbit of any star near this black hole.
Reconstruction of the orbits of two stars—S0-2 and S0-102—near the black hole at the Milky Way’s center. (Other stars’ orbits are also depicted by fainter lines.) The background is a real high-resolution infrared image of the region. Credit: Andrea Ghez et al./UCLA/Keck
In the same way that planets orbit around the sun, S0-102 and S0-2 are each in an elliptical orbit around the central black hole. Ghez said that the planetary motion in our solar system was the ultimate test for Newton’s gravitational theory 300 years ago, and now the motion of S0-102 and S0-2 will be the ultimate test for Einstein’s theory of general relativity, which describes gravity as a consequence of the curvature of space and time.
“The exciting thing about seeing stars go through their complete orbit is not only that you can prove that a black hole exists but you have the first opportunity to test fundamental physics using the motions of these stars,” Ghez said. “Showing that it goes around in an ellipse provides the mass of the supermassive black hole, but if we can improve the precision of the measurements, we can see deviations from a perfect ellipse — which is the signature of general relativity.”
As the stars come to their closest approach, their motion will be affected by the curvature of spacetime, and the light traveling from the stars to us will be distorted, Ghez said.
S0-2, which is 15 times brighter than S0-102, will go through its closest approach to the black hole in 2018. S0-102 makes its closest approach in 2021, so the team will be keeping an eye on these stars as they get tantalizingly close, but not close enough to get sucked in, Ghez said.
Ghez and her colleagues have been observing S0-2 since 1995. In 2000, she and her team reported — for the first time – that astronomers had seen stars accelerate around the supermassive black hole. Their research demonstrated that three stars had accelerated by more than 250,000 mph a year as they orbited the black hole. The speed of S0-102 and S0-2 should also accelerate by more than 250,000 mph at their closest approach, Ghez said.
“The fact that we can find stars that are so close to the black hole is phenomenal,” said Ghez. “Now it’s a whole new ballgame, in terms of the kinds of experiments we can do to understand how black holes grow over time, the role supermassive black holes play in the center of galaxies, and whether Einstein’s theory of general relativity is valid near a black hole, where this theory has never been tested before. It’s exciting to now have a means to open up this window.”
Lead image caption: The Keck I and Keck II telescopes focus on two stars orbiting Milky Way’s black hole. Background photo credit: Dan Birchall/Subaru Telescope on Mauna Kea, Hawaii. Overlay created by Professor Andrea Ghez and her research team at UCLA and are from data sets obtained with the W. M. Keck Telescopes.
A combined image of the Helix Nebula from the Spitzer Space Telescope,the Galaxy Evolution Explorer (GALEX) and the Wide-field Infrared Survey Explorer (WISE).. Credit: NASA/Caltech
The Helix Nebula has been called the “Eye of God,” or the “Eye of Sauron,” and there’s no denying this object appears to be a cosmic eye looking down on us all. And this new image – a combined view from Spitzer and GALEX — gives a blue tint to the eye that we’ve seen previously in gold, green and turquoise hues from other telescopes. But really, this eye is just a dying star. And it is not going down without a fight. The Helix Nebula continues to glow from the intense ultraviolet radiation being pumped out by the hot stellar core from the white dwarf star, which, by the way, is just a tiny white pinprick right at the center of the nebula.
The Helix nebula, or NGC 7293, lies 650 light-years away in the constellation of Aquarius. Planetary nebulae are the remains of Sun-like stars, and so one day – in about five billion years – our own Sun may look something like this — from a distance. Earth will be toast.
The team from the Spitzer Space Telescope and the Galaxy Evolution Explorer (GALEX) that cooperated to create this image describe what is going on:
When the hydrogen fuel for the fusion reaction runs out, the star turns to helium for a fuel source, burning it into an even heavier mix of carbon, nitrogen and oxygen. Eventually, the helium will also be exhausted, and the star dies, puffing off its outer gaseous layers and leaving behind the tiny, hot, dense core, called a white dwarf. The white dwarf is about the size of Earth, but has a mass very close to that of the original star; in fact, a teaspoon of a white dwarf would weigh as much as a few elephants!
The intense ultraviolet radiation from the white dwarf heats up the expelled layers of gas, which shine brightly in the infrared. GALEX has picked out the ultraviolet light pouring out of this system, shown throughout the nebula in blue, while Spitzer has snagged the detailed infrared signature of the dust and gas in red, yellow and green. Where red Spitzer and blue GALEX data combine in the middle, the nebula appears pink. A portion of the extended field beyond the nebula, which was not observed by Spitzer, is from NASA’s all-sky Wide-field Infrared Survey Explorer (WISE).
A Delta IV rocket launched from Florida today, sending a next-generation Global Positioning System satellite into orbit. The rocket lifted off at 12:10 UTC with the GPS IIF-3 satellite that will be part of the GPS system that is used by both civilians and the military. The new satellite will replace a 19-year-old navigation satellite in the global system that includes 31 operational satellites on-orbit which broadcast position, navigation and timing information to people around the world.
A United Launch Alliance Delta IV stands ready for launch at Space Launch complex 37 with the GPS IIF-3 satellite. Credit: ULA
The satellite, built by Boeing, is the third of 12 planned launches to provide improved GPS signals, featuring improved anti-jam technology, more precise atomic clocks, an upgraded civilian channel for commercial aviation and on-board processors that can be reprogrammed in flight, according to CBS News.
The new satellite should be operational by November.
When we posted an astrophoto earlier this week of a spectacular 22-degree Sun halo seen in Kuala Lumpur, we quickly got a note from Theo Wellington from Madison, Tennessee USA, who may have one-upped that image. Make that two-upped. “Not only did we have the 22 degree halo, but a circumscribed halo AND a parhelic circle as well!” Wellington wrote. “I became a distracted driver and had to pull off the road to look and photograph.” He added that Moon halo was seen the night before in the same location, as well.
What a stunning view — like a giant eyeball looking back at you!
Wellington used a Pentax K100D, 11mm fisheye lens, f13 1/4000, iso 400.
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Caption: The BloodhoundSSC. Image Credit: Curventa and Siemens.
29 years ago today Richard Noble in Thrust2 broke the land speed record for Britain at 633.468 mph in October 1983. That day saw the start of my love affair with the land speed record. Again in September 1997 Richard Noble’s ThrustSSC, driven by Andy Green, reached 714.144 mph and just a month later on October 15 Green became the first man to exceed the speed of sound at ground level, at 763.035 mph. Now Noble and Green have teamed up again to try to not just break that record but obliterate it.
Their supersonic car named BloodhoundSSC is jet and rocket powered and designed to go at 1,000 mph (just over 1,600 kph.) which is Mach 1.4 and faster than a bullet fired from a Magnum 357. Yesterday the test firing of its hybrid rocket engine at Newquay Airport in Cornwall, produced the loudest sound in the UK, 185 decibels!
Bloodhound’s slender body is approximately 14m long and 3m high, with two front wheels within the body and two rear wheels mounted externally encased in wheel fairings. The front half is a carbon fibre monocoque like a racing car, and the back half is a metallic framework with panels like an aircraft. It weighs, when fully fueled, almost 7 tonnes. But beneath its sleek blue and orange livery there lie engines with the power to produce more than 135,000 horsepower, capable of going from 0 to 1,000 mph in 42 seconds.
A Cosworth CA2010 Formula 1 engine will not drive the wheels, but will provide essential hydraulic services to the car and will also drive the rocket oxidizer pump which will supply 800 litres of High Test Peroxide (HTP) to the rocket’s fuel chamber in just 20 seconds, equivalent to 40 litres (over 9 gallons) every second. Half the thrust of Bloodhound is provided by the jet engine, a EUROJET EJ200, military turbofan used in Eurofighter Typhoons. The hybrid rocket for Bloodhound is the largest of its kind ever made in the UK. It will provide an average thrust of 111 kN (25,000 lbs) for 20 seconds. The peak thrust will be 122kN (27,500 lbs).
The Falcon Hybrid Rocket, designed by 28 year-old self-trained rocketeer Daniel Jubb, is 4 meters (12 feet) in length, 45.7 cm (18 inches) in diameter and weighs 450kg, and is the largest of its kind ever designed in Europe and the biggest to be fired in the UK for 20 years. It combines solid fuel (a synthetic rubber) with a liquid oxidiser (High Test Peroxide, or HTP) reacting with a catalyst (a fine mesh of silver) to produce its power.
The test firing was conducted inside a Hardened Air Shelter (HAS) with engineers, guests and media watching on a big screen from an adjacent building. The rocket burned for 10 seconds, generating 14,000 lbs of thrust, 30 – 40,000 hp. There will be a further 15 firings in Cornwall to prove the engine’s performance and certify its safety for use in a manned machine.
Next year the team hopes to break the world land speed record beyond the current 763mph, held by Green, and then try to reach 1,000mph in 2014. Hakskeen Pan, in the North Western corner of South Africa, has been chosen as the venue for the land speed record attempts currently 300 people are scraping all the debris from an area of desert surface measuring 19,000 by 500 m, that’s 9,500,000 square metres. Then a precision laser-guided grading vehicle, will complete the final cut, aiming for an accuracy of 10 mm across the whole of the area. As Bloodhound will cover 100 m in less than a quarter of a second at peak speed, even a 20 mm change of surface elevation would seem a massive bump.
And the reason behind this daring record attempt? It is to inspire and enthuse the next generation of scientists and engineers. It launched in 2008 to spur children’s interest in Stem subjects (science, technology, engineering and mathematics.) Education is at the heart of everything this project is about. It is basically a private venture that relies on donations.
Find out more about the project, get involved, or donate at the website
This image, called the Hubble eXtreme Deep Field (XDF), combines Hubble observations taken over the past decade of a small patch of sky in the constellation of Fornax. With a total of over two million seconds of exposure time, it is the deepest image of the Universe ever made, combining data from previous images including the Hubble Ultra Deep Field (taken in 2002 and 2003) and Hubble Ultra Deep Field Infrared (2009). The image covers an area less than a tenth of the width of the full Moon, making it just a 30 millionth of the whole sky. Yet even in this tiny fraction of the sky, the long exposure reveals about 5500 galaxies, some of them so distant that we see them when the Universe was less than 5% of its current age. The Hubble eXtreme Deep Field image contains several of the most distant objects ever identified. Credit: NASA
Astronomers using the Hubble Space Telescope recently released the deepest image of the sky ever obtained which reveals the faintest and most distant galaxies ever seen. The Hubble eXtreme Deep Field (XDF) is like a time machine, allowing us to see at how some galaxies looked just 450 million years after the Universe’s birth in the Big Bang.
Want to know more? The Kavli Foundation is hosting a live Q&A webcast on October 4 from 18:00- 18:30 UTC (11-11:30 am PDT) to provide the public a chance to ask questions of leading scientists about the image and the science behind it. Pascal Oesch, a Hubble Fellow at the University of California at Santa Cruz, and Michele Trenti, a researcher at the Kavli Institute for Cosmology, Cambridge at the University of Cambridge in the U.K., will discuss the image and answer questions about how the image was created and what it reveals about the early Universe. Watch the webcast below or at this link. Viewers may submit questions to the two Hubble researchers via Twitter using #KavliAstro or email to [email protected].
Lead image caption: The Hubble eXtreme Deep Field (XDF). Credit: NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team
Looking very similar to the iconic first footprint on the Moon from the Apollo 11 landing, this new raw image from the Curiosity rover on Mars shows one of the first “scuff” marks from the rover’s wheels on a small sandy ridge. This image was taken today by Curiosity’s right Navcam on Sol 57 (2012-10-03 19:08:27 UTC). Rover driver Matt Heverly described a scuff as spinning one wheel to move the soil below it out of the way.
Besides being on different worlds, the two prints likely have a very different future. NASA says the first footprints on the Moon will be there for a million years, since there is no wind to blow them away. Research on the tracks left by Spirit and Opportunity revealed the time scale for track erasure by wind is typically only one Martian year or two Earth years.
Here’s one of Buzz Aldrin’s bootprint, to compare:
The GRIN website (Great Images in NASA) says this is an image of Buzz Aldrin’s bootprint from the Apollo 11 mission. Neil Armstrong and Buzz Aldrin walked on the Moon on July 20, 1969. Credit: NASA
Curiosity chief scientist John Grotzinger compared earlier images of some of the first tracks left on Mars by Curiosity to images of the footprints left by Aldrin and Armstrong on the Moon. “I think instead of a human, it’s a robot pretty much doing the same thing,” he said.
