November 13, 2014 // Jean-Pierre Joosting

Physics and astronomy depend on being able to register a barely detectable electrical signal in the microwave regime to learn and make discoveries. A typical example of this was the discovery of cosmic background radiation that helped confirm the Big Bang theory. Another example is the detection of data from scientific instruments in space missions on their way to distant planets, asteroids or comets.

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Faint microwave signals are detected by transistor-based low-noise amplifiers. Researchers at Chalmers University of Technology have optimised indium phosphide transistors using a special process for this purpose. A spin-off company from Chalmers, Low Noise Factory, designs and packages amplifier circuits.

This is an electron microscope image of an indium phosphide high electron mobility transistor (InP HEMT). The region affected by the self-heating process is highlighted in the cross section of the InP HEMT. Credit: Chalmers University of Technology

"Cooling the amplifier modules to -260 degrees Celsius enables them to operate with the highest signal-to-noise ratio possible today," says Jan Grahn, Professor of microwave technology at Chalmers. "These advanced cryogenic amplifiers are of tremendous significance for signal detection in many areas of science, ranging from quantum computers to radio astronomy."

Using a combination of measurements and simulations, the researchers investigated what happens when a microwave transistor is cooled to one tenth of a degree above absolute zero (-273 degrees Celsius). It was thought that noise in the transistor was limited by so-called hot electrons at such extreme temperatures. However, the new study shows that the noise is actually limited by self-heating in the transistor.

Physics and astronomy depend on being able to register a barely detectable electrical signal in the microwave regime to learn and make discoveries. A typical example of this was the discovery of cosmic background radiation that helped confirm the Big Bang theory. Another example is the detection of data from scientific instruments in space missions on their way to distant planets, asteroids or comets.

Faint microwave signals are detected by transistor-based low-noise amplifiers. Researchers at Chalmers University of Technology have optimised indium phosphide transistors using a special process for this purpose. A spin-off company from Chalmers, Low Noise Factory, designs and packages amplifier circuits.

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Microwave amplifier noise limited by quantum particles of heat

Astronomy - Ch. 17: The Nature of Stars (2 of 35) What is Apparent Magnitude?
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Astronomy Cast 357: Vera Rubin

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KALIAMBOS - AMPHIPOLIS TOMB (ASTRONOMY AND PUZZLE)
My discovery of the diameter d of the Amphipolis tomb circular base (d =1 Alexandrian stadion = 157.5 m) confirms the measurements of the Greek mathematician Eratosthenes ( 250 BC ) who found...

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13-Nov-2014

Contact: Chris Sasaki media@dunlap.utoronto.ca 416-978-6613 Dunlap Institute for Astronomy & Astrophysics @dunlapinstitute

TORONTO, ON (13 November 2014) Astronomers from the University of Toronto and the University of Arizona have provided the first direct evidence that an intergalactic "wind" is stripping galaxies of star-forming gas as they fall into clusters of galaxies. The observations help explain why galaxies found in clusters are known to have relatively little gas and less star formation when compared to non-cluster or "field" galaxies.

Astronomers have theorized that as a field galaxy falls into a cluster of galaxies, it encounters the cloud of hot gas at the centre of the cluster. As the galaxy moves through this intra-cluster medium at thousands of kilometres per second, the cloud acts like a wind, blowing away the gas within the galaxy without disturbing its stars. The process is known as ram-pressure stripping.

Previously, astronomers had seen the very tenuous atomic hydrogen gas surrounding a galaxy get stripped. But it was believed that the denser molecular hydrogen clouds where stars form would be more resistant to the wind. "However, we found that the molecular hydrogen gas is also blown from the in-falling galaxy," says Suresh Sivanandam of the Dunlap Institute at the University of Toronto, "much like smoke blown from a candle being carried into a room."

Previous observations showed indirect evidence of ram-pressure stripping of star-forming gas. Astronomers have observed young stars trailing from a galaxy; the stars would have formed from gas newly-stripped from the galaxy. A few galaxies also have tails of very tenuous gas. But the latest observations show the stripped, molecular hydrogen itself, which can be seen as a wake trailing from the galaxy in the direction opposite to its motion.

"For more than 40 years we have been trying to understand why galaxies in dense clusters have so few young stars compared with ones like our Milky Way Galaxy, but now we see the quenching of star formation in action," says George Rieke of the University of Arizona. "Cutting off the gas that forms stars is a key step in the evolution of galaxies from the early Universe to the present."

The results, published in the Astrophysical Journal on Nov. 10, are from observations of four galaxies. Sivanandam, Rieke and colleague Marcia Rieke (also from the University of Arizona) had already established that one of the four galaxies had been stripped of its star-forming gas by this wind. But by observing four galaxies, they have now shown that this effect is common.

The team made their analysis using optical, infrared and hydrogen-emission data from the Spitzer and Hubble space telescopes, as well as archival ground-based data. The team used an infrared spectrograph on the Spitzer because direct observation of the molecular hydrogen required observations in the mid-infrared part of the spectrum--something that's almost impossible to do from the ground.

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The answer is blowing in the intergalactic wind

Jupiters Great Red Spot, which has tantalized astronomers for centuries, may be caused by something as surprisingly mundane as ultraviolet (UV) tanning at extremely high altitude, say researchers at NASAs Jet Propulsion Laboratory (JPL).

New analysis of NASA Cassini mission observations made during a December 2000 Jupiter flyby, coupled with ground-based lab experiments, point to very high altitude solar photolysis (or the molecular breakup) of ammonia and hydrocarbons at the top of this puzzling red vortex, located in our largest planets southern hemisphere.

High altitude UV radiation from the sun photolyzes ammonia and hydrocarbons, such as methane, in close proximity with each other and in the process creates a bright red cyanide-like molecule, Kevin Baines, a planetary scientist and JPL Cassini team member, told Forbes.

Research suggests effects of sunlight produce the color of Jupiters Great Red Spot. The features clouds are much higher than those elsewhere on the planet, and its vortex nature confines the reddish particles once they form. Image credit: NASA/JPL-Caltech/ Space Science Institute

This week, Baines outlined his and colleagues new hypothesis about the chemical processes that drive the oval-shaped Great Red Spot during a divisional meeting of the American Astronomical Society (AAS) in Tucson. Baines says this whole process depends on having aerosols, particularly ammonia ice particles, lofted upwards to a very high part of the atmosphere where the sunlight is not filtered by overlying gases. As a result, he says, the clouds inside are more susceptible to UV photolysis.

The Red Spot reaches a very high altitude; about 50,000 ft higher than other [nearby] clouds, said Baines. The sunlight is more powerful and direct and

Baines and colleagues used spectral images of the Red Spot, taken by Cassinis Visible and Infrared Mapping Spectrometer (VIMS) to gain new insight into the Red Spots inner workings and as a basis of comparison for their ground-based lab work.

Using a JPL lab, the team performed UV photolysis of acetylene and ammonia, both of which are found in Jupiters atmosphere, and were able to recreate the colors that they see in the planets signature spot.

But why is this Great Spot Red?

This upper layer cooks and turns red, says Baines. As he explains, ammonia-laced clouds whirl around this rarefied upper atmospheric layer in which UV radiation splits an atom of hydrogen from a molecule of ammonia. This free hydrogen atom in turn then runs around and couples with carbon and hydrogen atoms stripped from broken molecules of methane (or some other hydrocarbon) to create a form of red cyanide; providing the Red Spot with its color.

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Jupiter's Great Red Spot Likely One Big UV 'Sunburn'

Astronomy - Ch. 17: The Nature of Stars (2 of 35) This Video Has an Error
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Supernova Remant #39;Dissected #39; By Astronomy Research Center | Visualization
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The European Space Agency (ESA) reports that following a night of Go/NoGo decision-making, its cometary lander has successfully separated from the Rosetta spacecraft in orbit around the comet 67P/ChuryumovGerasimenko and is now heading to its surface.

Despite a problem with the landers gas thruster, if the 150 kg Philae is able to successfully maneuver its way onto the boulder-strewn surface of the mile-long body located some 500 million km from Earth, it will mark the first time a spacecraft has been able to touch down on the surface of a comet itself. Now in its 98th day of orbit around 67P, it has taken more than a decade for the Rosetta mission to finally cross this crucial Rubicon.

ESA reports that after performing a series of checks on the landers health, the Philaes active descent system was found to be non-operational. During the final phase of descent, the thruster would have been used to avoid what ESA terms rebound at the moment of touchdown.

Credit: ESA

This means that at the moment of impact on the surface of the comet, in an area dubbed Agilkia, the Philae lander will have to rely solely on ice screws and harpoons to secure itself to the surface. The downward thruster atop the lander was to have been used to counteract the impulse of the harpoons being thrust in the opposite direction.

The cold gas thruster on top of the lander does not appear to be working so we will have to rely fully on the harpoons at touchdown, Stephan Ulamec, Philae lander manager at the DLR German Aerospace Center told an early morning press conference. Well need some luck not to land on a boulder or a steep slope.

Even so, Rosettas controllers at the at ESAs Space Operations Centre in Darmstadt, Germany note that the spacecrafts overall health remains good. However, after the lander separates from the orbiter, ESA doesnt expect the orbiter to receive signals from Philae for at least two hours or until the lander establishes communication with the Rosetta orbiter.

The descent to the comet itself is expected to take some seven hours with confirmation of touchdown not expected until 6:02 PM (CET)/1:02 PM (EST) Wednesday.

The lander should begin its science mission on the oddly-shaped comet as soon as it touches down. Researchers emphasize that exploration of such comets are crucial to understanding the primordial solar system; the origin of both our solar system and even life itself.

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ESA Lander Now Headed To Comet's Surface [Updated]

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"Its a myth that the sun is stationary. It rotates and revolves around its own axis. The sun is very important as it gives us life. Thus, all of us are star children." said professor S Natarajan to more than 35 children and adults at a Powai housing society. With a five inch reflector telescope, 49-year-old Mahim resident Natarajan has been spreading knowledge on astronomy for more than 18 years, and that too free of cost.

Natarajan graduated with a BA in English literature but has been passionate about astronomy ever since he was a child. "I was eight years old when my father showed me the north star and that's when I fell in love with this subject," said Natarajan who is also an honorary lecturer at Nehru planetarium since 1984.

What began in childrens' parks with a lot of suspicion from parents and elders, this endeavour has reached across India where he has conducted more than 3,000 lectures. Natarajan has travelled to small towns, villages and cities to educate literate as well as illiterate people about the various galaxies, constellations, planets, the moon, birth and death of stars and eclipses to dispel long held traditional beliefs. "The subject of astronomy is not taught well in school. It is my mission to create scientific temperament regarding this topic and to disprove superstitions. I got operated on my varicose veins on the day of the recent lunar eclipse," said Natarajan, who is also a BSNL employee.

Shalini Virat, whose children attended the program said that this was the second time they had invited professor Natarajan. "Three months ago we saw planets and the moon in the sky and when children see what they are taught in school, they retain it better,"she said.

Natarajan has travelled to Gujarat, Chandigarh, Delhi, Tamil Nadu, Chandigarh, Punjab and Himachal Pradesh and wherever he goes, he only charges for conveyance and not for the lectures. Dr Uma Sivaraman, the assistant commissioner of Kendriya Vidyalaya Sanghatan in Chennai, has known him for more than 15 years. She has invited him to conduct more than 13 shows all over the country. "He is able to instill interest in children and you can see the joy on their faces when they see the night sky. These days children are so busy that they don't go out of the house, forget watching the night sky," she said over the phone.

Twenty one-year-old Pooja Tolia is another honorary lecturer at the planetarium who teaches the making of telescopes. She has been motivated by him to take up imparting of education on a bigger scale. "Many people confuse astronomy with astrology. With his style of teaching, people of all age groups understand the topic. He has helped me improve my communication skills and pushed me to conduct such programs," she said.

The next thing on Natarajan's timeline is approaching hotels for star gazing and other astronomy events. "Astronomy teaches man humility, which in turn boosts creativity and innovation," he said.

Contact of S Natarajan Phone: 9869264477 Email: natarajans23@gmail.com

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Free astronomy lessons for the starry-eyed

As part of an international collaboration, scientists at Chalmers University of Technology have demonstrated how noise in a microwave amplifier is limited by self-heating at very low temperatures. The results will be published in the journal Nature Materials. The findings can be of importance for future discoveries in many areas of science such as quantum computers and radio astronomy.

Many significant discoveries in physics and astronomy are dependent upon registering a barely detectable electrical signal in the microwave regime. A famous example of this was the discovery of cosmic background radiation that helped confirm the Big Bang theory. Another example is the detection of data from scientific instruments in space missions on their way to distant planets, asteroids or comets.

Faint microwave signals are detected by transistor-based low-noise amplifiers. Researchers at Chalmers University of Technology have now optimised indium phosphide transistors using a special process for this purpose. A spin-off company from Chalmers, Low Noise Factory, designs and packages amplifier circuits.

"Cooling the amplifier modules to -260 degrees Celsius enables them to operate with the highest signal-to-noise ratio possible today," says Jan Grahn, Professor of microwave technology at Chalmers. "These advanced cryogenic amplifiers are of tremendous significance for signal detection in many areas of science, ranging from quantum computers to radio astronomy."

Using a combination of measurements and simulations, the researchers investigated what happens when a microwave transistor is cooled to one tenth of a degree above absolute zero (-273 degrees Celsius). It was thought that noise in the transistor was limited by so-called hot electrons at such extreme temperatures. However, the new study shows that the noise is actually limited by self-heating in the transistor.

Self-heating is associated with phonon radiation in the transistor at very low temperatures. Phonons are quantum particles that describe the thermal conductivity of a material. The results of the study are based on experimental noise measurements and simulations of phonons and electrons in the semiconductor transistor at low temperatures.

"The study is important for the fundamental understanding of how a transistor operates close to absolute zero temperature, and also how we should design even more sensitive low-noise amplifiers for future detectors in physics and astronomy," explains Jan Grahn.

The research has been performed as part of an international exchange between Chalmers University of Technology in Sweden and the California Institute of Technology. Co-authors are the University of Salamanca and the Swedish company Low Noise Factory. The study was conducted at the Gigahertz Centre, a joint venture between Chalmers, research institutes, company partners and the Swedish Governmental Agency for Innovation Systems (Vinnova).

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The above story is based on materials provided by Chalmers University of Technology. Note: Materials may be edited for content and length.

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Noise in a microwave amplifier is limited by quantum particles of heat

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Astronomy - Ch. 17: The Nature of Stars (1 of 35) Introduction
Visit http://ilectureonline.com for more math and science lectures! In this video I will introduce the nature of stars: How far? How big? How bright? How Long Do They Last? How are They Born?

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The stars came out for a charity night to raise cash for the proposed 8.5m Kielder Observatory Astronomy Village.

The main speaker was NASA flight controller Sy Liebergot who played a crucial role in bringing the stricken Apollo 13 back to earth safely.

And the event was hosted in the Moncur Suite at St James Park, home of Newcastle United, by diehard Sunderland fan and Athletics legend Steve Cram.

Steve, now a respected TV commentator, joked at the beginning of the evening. Its not often I can say its a pleasure to come to St James Park.

Meanwhile Toon star Bob Moncur, who the suite was named after and also attended, hit back: Steves not used to big crowds.

The black tie event, funded by Cramlington-based manufacturing company Miller International, marked the official launch of the astronomy village project.

It included an auction of some, literally, out of this world lots including a rare 2.13g slice of lunar meteorite, a piece of the NASA space shuttle signed by Sy Liebergot, and a facsimile of the Apollo 13 checklist, again signed by Sy as well as astronauts on the mission Jim Lovell and Fed Haise.

Movie fans may remember the Ron Howard film Apollo 13 which recreated the dramatic events of the mission.

However pride of place went to a framed dollar bill, signed by members of the Apollo 11 mission which was the first to land on the moon. They were Neil Armstrong, the first man to set foot on the moon, Buzz Aldrin and Michael Collins.

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Stars come out for charity night in aid of Kielder Observatory Astronomy Village plan

An aluminum fuselage fragment purported to be from Amelia Earharts 1936 twin-engine Lockheed Electra 10E Special, actually dates from World War II (or at least several years after Earhart went missing), Gary LaPook, a California-based attorney specializing in aviation accident investigations told Forbes.

The slightly rectangular, roughly three sq ft fragment was found on the uninhabited southwest Pacific atoll of Nikumaroro in 1991. But it was recently offered by Tighar, a prominent Earhart search group, as fresh fodder for the hypothesis that on July 2, 1937, Earhart and her navigator Fred Noonan crash-landed on one of the islands outlying coral reefs. That is, after completely missing tiny Howland Island some 400 miles to the north. An unprecedented air and sea search at the time turned up nothing.

Amelia Earharts Lockheed Model 10 Electra, at Oakland, CA on March 20, 1937. Scanned from Lockheed Aircraft since 1913, by Ren Francillon. Photo credit USAF. (Photo credit: Wikipedia)

The International Group for Historic Aircraft Recovery (Tighar)s claim is that after leaving Lae, New Guinea around Noon on July 2nd, Earhart was actually as much as 200 miles south of Howland as part of her attempt to finish a weeks-long second attempt to complete a west to east round-the-world journey. The Pennsylvania-based Tighars idea is that they then ran south on a navigational line of position and hit Nikumaroro, then known as Gardner Island.

Yet Tighars executive director Ric Gillespie and LaPook disagree on the dates and labeling of the artifact fragment which Tighar found on Nikumaroro.

The skin of the aircraft [fuselage] was made of an aluminum alloy and to protect it from corrosion was then coated with pure aluminum known as ALCLAD for aluminum clad, said LaPook, who is also a celestial navigation instructor and former commercial transport pilot. On the back of the fragment, only the AD of the longer marking ALCLAD is still legible, a label that LaPook maintains would not have been in use until years after Earharts doomed flight.

But Gillespie, who is also author of Finding Amelia: The True Story of the Earhart Disappearance, contends that aluminum sheets on such 1930s aircraft were first marked with the ALCLAD [aluminum clad] label; then the letters ALC, before Alcoa Alcoa finally switched the labeling back to ALCLAD.

LaPook however counters that the ALCLAD labeling followed the earlier ALC labeling by several years and the switch was made during World War II.

My challenge to Gillespie still stands, if they ever marked aluminum with the word ALCLAD prior to Earharts disappearance, then he has the burden of proving it by producing one other piece of it with that marking, said LaPook. Nor has he come up with any photos showing such ALCLAD aluminum [markings] being used prior to July 2, 1937.

Gillespie told Forbes that Tighar has yet to find any piece of metal or photograph of a piece of metal that has exactly the same font on it as the artifact. But he says there are other features about the artifact that fit perfectly with it being part of a patch from Earharts aircraft.

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Aircraft Fragment Likely Not Amelia Earhart's, Says Investigator