An extraordinary outburst produced by a black hole in a nearby galaxy has provided direct evidence for a population of old, volatile stellar black holes.
The discovery, made by astronomers using data from NASA's Chandra X-ray Observatory, provides new insight into the nature of a mysterious class of black holes that can produce as much energy in X-rays as a million suns radiate at all wavelengths.
These objects give off more X-rays than most binary systems, in which a companion star orbits the remains of a collapsed star. These collapsed stars form either a dense core called a neutron star or a black hole.
The extra X-ray emission suggests ULXs contain black holes that might be much more massive than the ones found elsewhere in our galaxy.
A paper describing these results will appear in the May 10, 2012, issue of The Astrophysical Journal.
Image Credits: X-ray: NASA/CXC/Curtin University/R. Soria et al., Optical: NASA/STScI/ Middlebury College/F. Winkler et al.
The first detailed image of filamentary structure traced in the Northern part of the Orion A cloud, showing where the stars are forming from clumps of cold gas and dust.
The ability to image condensations of cold dust with the earlier SCUBA camera, and more recently with SCUBA-2, has made the JCMT one of the choice instruments in the world for studying the earliest stages of star formation.
The James Clerk Maxwell Telescope celebrates it's 25th anniversary. Named after the famous Scottish Physicist and Astronomer, James Clerk Maxwell who inspired Newton and other groundbreaking scientists. W51, shown here, is located in the constellation of Aquila. It is one of the most massive regions of star formation within the galaxy.
It is in stellar nurseries such as this that the stars form with enough mass to go on to end their lives in Supernova explosions.
The background is a mid-infrared Spitzer image while the blue overlay is 850μm data from JCMT's SCUBA-2 in Hawaii, and is sponsored by the UK STFC.
The red colours in this image show the galaxy M66 as it appears at the sub-mm wavelength of 850 microns, while the white background shows the galaxy as it appears in visible light.
Regions of cold dust that appear as dark streaks in the white image glow brightly in the red image.
The center of the galaxy contains much more dust than is obvious from looking at the visible image and the sub-mm image also picks out an unusual compact cloud in the southern part of the galaxy that is a prime site for future star formation. Credit: VLT/ESO, JAC, G. Bendo.
One of the world's most powerful cameras, SCUBA-2 is producing its first detailed images of our neighbouring galaxies, revealing previously undetected vast pockets of star formation where the next generation of stars is being created.
The light from these stars is usually obscured by dust, but at the sub-millimetre wavelengths that the camera is designed for, these dust lanes actually glow brightly. The images are revealed in the week of the 25th anniversary of the James Clerk Maxwell Telescope, in Hawaii on which SCUBA-2 is mounted.
"This exquisite image from the galaxy M66 in the constellation Leo is exactly the promising start we were hoping for," said Dr. Stephen Serjeant, the team's co-leader from The Open University. "This is a wonderfully exciting taste of things to come."
When looking up at the Milky Way, an irregular pattern of dark regions obscures the light of the stars. The dark patches are caused by clouds of dust trailing through the spiral arms and blocking out the starlight that would otherwise reveal vast pockets of star formation, or stellar nurseries. These dark lanes are not exclusive to the Milky Way, but can be found in all spiral galaxies.
SCUBA-2, led by STFC's UK Astronomy Technology Centre in Edinburgh is the most powerful camera ever developed for observing light at sub-milimetre wavelengths, 1000 times longer than we can see with our eyes.
This makes it possible to detect stellar nurseries usually obscured by dust that are so remote the light they emit left them within the first billion years after the big bang.
University of Edinburgh astrophysicist Professor James Dunlop said: "These beautiful new images from SCUBA-2 show energy conservation in action, as the same dust which absorbs the blue optical light (obscuring the stars in the optical images) can be seen to re-emit at the much longer wavelengths accessible to SCUBA-2."
For example, galaxies in dense clusters can lose their gas and dust through interactions with other galaxies in the cluster or simply by the head wind they feel while moving through the hot gas trapped inside the cluster.
The NGLS is an international collaboration led by astronomers from Canada, the Netherlands, and the United Kingdom which is using SCUBA-2 to observe 150 galaxies in the local universe.
The NGLS team has spent much of the last five years studying molecular hydrogen emission using another instrument on the James Clerk Maxwell Telescope.
"It is very exciting to now see the first results from the SCUBA-2 side of our programme starting to come in," says Professor Christine Wilson, the Principal Investigator from McMaster University in Canada.
"We have a unique sample of galaxies that we are studying and having SCUBA-2 data will let us measure their gas and dust content. Gas and dust usually go hand-in-hand in galaxies, but from time to time, you find a surprise."
By the virtue of their size and speed, birds are uniquely capable of
efficient flight while flapping their wings and while gliding.
Researchers at the University of Illinois at Urbana-Champaign have
duplicated the control functions that allow birds to successfully
perform a soft landing—in this case, perching on a human hand.
“We believe we have the first demonstration of autonomous/robotic
flight of a bird-like micro aerial vehicle (MAV) perching on a human
hand,” stated Soon-Jo Chung, an assistant professor in the Department of
Aerospace Engineering at Illinois.
Because the wings of ornithopters—birds or aircraft with flapping
wings—are inherently capable of being reoriented, this capability can be
used for controlling and maneuvering the aircraft in a gliding phase,
thereby eliminating the need for additional traditional actuators.
Gliding is an effective way to conserve energy while soaring,
descending, and landing.
“The driving philosophy behind the work is that the maneuverability and
control efficiency of avian flight can be replicated by applying their
actuation and control principles to advanced MAVs designed on the size
scale of small birds,” explained Aditya Paranjape, a postdoctoral
scholar working on this project.
The result is based on his PhD thesis
and a series of journal papers with Chung.
“We have developed an articulated-wing-based concept for an agile
robotic aircraft inspired by birds,” Paranjape added. “Of all manoeuvers
executed by flapping wing aircraft in a gliding phase, a perched landing
is arguably the most challenging.”
Perching is routinely used by birds to land on objects such as tree
branches, power wires, or building ledges. According to the researchers,
there are two factors that make perching challenging to engineer: 1)
the maneuver’s duration is very short, on the same order as the aircraft
dynamics, and 2) a high level of position accuracy is required for a
successful perched landing.
“Our aerial robot concept lacks a vertical tail for improved agility,
similar to birds, which renders it dynamically unstable and exacerbates
both of these factors,” Paranjape said. “We choose a perching maneuver
to demonstrate the capabilities of our articulated-winged aircraft
concept, novel guidance algorithms, and control design.
In particular,
the ability to perform perched landings on a human hand endows our robot
with the ability to operate around humans.”
A typical perching maneuver consists of two phases—a gliding phase to
bring the bird to a suitable position with respect to the landing spot,
and a rapid pitch up (usually to a post-stall angle of attack)
accompanied by an instantaneous climb and rapid deceleration.
The
researchers noted that the success of the maneuver can be severely
impeded by the lateral-directional motion (yaw and roll), particularly
when the perched landing has to be accomplished on a small surface such
as an electric pole or a human palm.
In the absence of a vertical tail,
wing articulation is a promising capability which can be used for both
longitudinal and lateral-directional control.
Chung, who joined the Illinois’ faculty in 2009, brought with him a
vision for developing aircraft that mimic the autonomy and agility of
bats.
“There’s a lot to learn from bio systems,” Chung said. “Bats can fly
with damaged wings. They are so agile and highly maneuverable; they can
make rapid 180-degree turns autonomously and they can fly indoors
without colliding with obstacles. These qualities are desirable for
small aircraft that could be used in surveillance, particularly in urban
settings where obstacles hamper movement and satellite control is
blocked.”
The MAV project was funded by the Air Force Office of Scientific Research.
The technical details of this work can be found in the following papers.
A. Paranjape, J. Kim, and S.-J. Chung, "Closed-Loop Perching of Aerial Robots with Articulated Flapping Wings," IEEE Transactions on Robotics, under review, 2012. https://netfiles.uiuc.edu/sjchung/www/Paranjape12_perching_submitted.pdf
A. A. Paranjape, S.-J. Chung, H. H. Hilton, and A. Chakravarthy, "Dynamics and Performance of a Tailless MAV with Flexible Articulated Wings," AIAA Journal, vol. 50, no. 5, May 2012, pp. 1177-1188. https://netfiles.uiuc.edu/sjchung/www/AIAAJflexnew.pdf
What would it feel like to be an astronaut on Mars?
Physicist Daniel Schildhammer wears the Aouda.X spacesuit simulator
during a field test of Oesterreichisches Weltraum Forum (Austrian space forum) inside the Eisriesenhoehle (giant ice cave) at Dachstein mountain
near the village of Obertraun April 28, 2012.
The outfit mimics Mars's lower atmospheric pressure and is equipped for extreme temperatures, with an onboard computer that controls a heating and cooling system based on information from a network of sensors.
Headphones allow the wearer to communicate wirelessly with colleagues on smartphones, with a radio backup should the main system fail.
Compared to the first version of the suit, which was tested in 2009, the current model is equipped with more robust electronics and a better voice recognition system to control field instruments.
However, according to Gernot Groemer, (www.ostina.org) the team leader, there are still improvements to be made. "The goal is to create a simulation that's so realistic that by closing your eyes, you would think you were on Mars," he says.
The suit is being tested in ice caves at Dachstein mountain in Austria to simulate astrobiology experiments. It is designed to collect samples without contaminating the external environment as long as the right procedures are followed. These are currently being evaluated at the site.
Expedition 30 Commander Dan Burbank of NASA, Russian Soyuz Commander Anton Shkaplerov and Flight Engineer Anatoly Ivanishin landed safely on the steppe of Kazakhstan on April 27, 2012, after bidding farewell to the Expedition 31 crew and undocking their Soyuz TMA-22 spacecraft from the International Space Station.
The trio completed almost six months in space following a launch in November 2011. They are shown being assisted into reclining chairs by Russian personnel and beginning their adaptation to gravity after they were extracted from their capsule in Kazakhstan.
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