Hypergiant Star Amazes for 30 Years

A European research team has published the results of a 30-year study of an extraordinary hypergiant star. They have found that the surface temperature of the super-luminous star HR 8752 increased by about 3000 degrees in less than three decades, while it went through an extremely rare stage called the 'Yellow Evolutionary Void'. The discovery marks an important step closer to unravelling the evolution of the most massive stars.

A team of astronomers from six European countries, including the Royal Observatory of Belgium (ROB), has investigated the hypergiant star HR 8752 for 30 years while it traversed the 'Yellow Evolutionary Void'. The 'Void' is a short stage in the lives of the most massive stars when they become very unstable. The team finds that the surface temperature of HR 8752 rose surprisingly fast from 5000 to 8000 degrees in less than 30 years. The research results were very recently published in the journal Astronomy and Astrophysics. The discovery is an important step forward to resolve the enigma of the hypergiants, the most luminous and massive stars of the Galaxy.

Hypergiants can shine millions of times brighter than the Sun, and they often have a diameter several hundred times greater. HR 8752 is a quarter million times more luminous than the Sun. The powerhouse is therefore visible with normal binoculars at large distance from Earth in the Northern constellation of Cassiopeia. There are currently only 12 hypergiants known in our Galaxy.

The 'Yellow Evolutionary Void' is a unique stage in the short life of a hypergiant when its temperature and luminosity can quickly change. The team has discovered that the atmospheres are very unstable inside the Void because outwardly directed forces act equal or sometimes even stronger than the force of gravity. Due to the unstable atmosphere, hypergiants lose tremendous weight in this 'forbidden zone', which can sometimes amount to the mass of the Sun in a year. When a hypergiant enters the 'Evolutionary Void' the star tries to it leave as quickly as possible. That is why almost all hypergiants are found outside the Void.

The team finds that HR 8752 is a very rare hypergiant which has partly traversed the Void. The changes of its atmosphere were closely monitored with regular observations over 30 years.

Alex Lobel, co-author of the study and ROB scientist explains that "HR 8752 was around 1980 identical to the eruptive hypergiant Rho Cas of spectral type F, but then the temperature of HR 8752's atmosphere rapidly increased by 3000 degrees and now shows the spectral properties of a hotter A-type star. We are baffled about the tremendous changes of HR 8752 in that period of time."

Between 1900 and 1980 the atmospheric temperature of HR 8752 stayed almost constant around 5000 degrees, but it rose very rapidly to 8000 degrees between 1985 and 2005. The team calculates that the stellar radius decreased from 750 to 400 times that of the Sun. In 1985 the team embarked on a long-term spectroscopic observing program when it found that the remarkable hypergiant was exactly at the border of the 'Yellow Void' and started to cross over. "HR 8752 had to struggle through the Void which has changed the physical properties of its atmosphere," Lobel adds.

The team further demonstrates that the Void actually consists of two parts in which the atmosphere of the hypergiant is unstable. They result from ionization of large amounts of hydrogen and helium gas in the atmosphere, divided by a small zone around 8000 degrees where it becomes more stable.

The fate of HR 8752 is currently unclear but there are strong hints that these massive hypergiants may perish in a powerful supernova explosion. Or they quickly traverse the Void and transform into a hotter type of erratic stars known as the "Luminous Blue Variables." In either case that will not pass unnoticed according to Kees de Jager and Hans Nieuwenhuijzen, the astronomers of the Netherlands Institute for Space Research in Utrecht who directed the research of HR 8752 over the past three decades.

The discovery is an important new step for explaining the existence of these extreme stars. A number of other hypergiants with similar spectacular properties is expected to exist in the Milky Way. The search for these remarkable stars with dramatic changes over human timescales has just begun, but has been forever put on track.

Story source:

Science Daily

M.D

Nanodiamond Circuits to Work in Extreme Conditions

Scientists at Vanderbilt University have developed computer chips and circuits made up of Diamond film to make them more venerable than their silicon counterparts. Transistors and Logic gates of Diamond have already been developed and they are now working to create complete microelectronic devices with diamond parts. Such devices can operate at higher speed and need less power than silicon made devices.

In journal Electronics Letters, the design of such diamond logic gates have been described. Research Professor and head of team, Jimmy Davidson said that devices using diamond parts will not be expensive as 1 carat of diamond can be fabricated to make around 1 billion such devices. Diamond films used to create these devices are made up chemical vapor deposition technique that uses hydrogen and methane. This form of diamond is much cheaper than conventional diamond used in jewelry. This makes them economical and a tough competitor to silicon parts,according to Spoken Science.

Nanodiamond circuits use technologies of old fashioned vacuum tubes as well as solid state microelectronics. A thin film of diamond is laid down on silicon oxide layer. This facilitates movement of electrons through vacuum between nanodiamond components. This reduces the problem of heating up of normal microelectronics devices as in these types of devices a vacuum movement of electron occurs. Also diamond being the best electron emitter needs much less energy to produce electron beams, which in turn reduced the electricity consumption to operate these devices.

Another major advantage of nanodiamond devices is that such devices are immune to radiation damage which causes the tripping of circuits in normal electronics devices. As electrons moves in vacuum in nanodiamond devices, there are no energetic particles to disrupt.

So you can easily imagine the benefits of such nanodiamond devices.

 

M.W

 

Sarkis calls for assessing damages caused by terrorists to environment in Aleppo

 ALEPPO, (ST)- Minister of State for Environment Affairs Nazira Sarkis has urged environment-concerned bodies to specify the environmental damages caused by the sabotage acts perpetrated by armed terrorists groups in Aleppo and find necessary solutions to protect the environment.

During her meeting on Saturday with Aleppo Environment Directorate staff, Sarkis stressed the importance of intensifying efforts being exerted to enhance environment protection, calling for more cooperation between the Directorate and research centers in Aleppo University to assess the damages caused by terrorists to the environment in the governorate of Aleppo.

She also affirmed the need to evaluate the environmental situation in Aleppo, including the safety of water, air and soil, calling for more cooperation among people's organizations and civil society associations to protect environment from pollution, disseminate awareness about environment pollutants and urge citizens to participate in cleaning campaigns.

Sarkis said the Ministry is currently working on providing the National Environmental Observatory with the data needed aiming at drawing up a map for the current and future environment situation in all Syrian governorates.

For his part, Aleppo Governor Mohammad Wahid Akkad said the governorate continues to observe environment pollutants particularly in poor districts and works hard to treat environment problems.

H. Moustafa

Will we ever… have safe cigarettes?

There’s an old saying among people who work in public health: Tobacco is the only legal product that, when used as intended, will kill you. Decades of research have thoroughly documented the health problems that result from inhaling tobacco smoke – more than a dozen different types of cancer, heart disease, stroke, emphysema and other respiratory diseases, among others. Are these risks an inevitable part of smoking? Or is there a way of creating safe cigarettes without any of these hazards?

“I think it’s very unlikely,” says Stephen Hecht from the University of Minnesota Cancer Center, who studies tobacco carcinogens – substances that cause cancer. Tobacco smoke is a complex cocktail of at least 4,000 chemicals including at least 70 known carcinogens. No one has made a “cigarette that is significantly decreased in all of these [chemicals] and is still something people would want to smoke, even though the industry has worked on this for around 50 years,” says Hecht. “There’s no indication that it’s possible.”

 As Hecht says, it’s not that the industry hasn’t tried. Journalist Will Storr recently documented a history of bungled attempts to create a safer cigarette, from one that passed the carcinogenic smoke through a filter made of another carcinogen – asbestos – to another that heated tobacco rather than burning it, but tasted of sulphur, charcoal, and burning plastic.

 The problem is that no single step in the production or consumption process fills cigarette smoke with its dangerous constituents. Some constituents are in the tobacco leaves themselves at the point of harvesting. The plants can absorb metals and metalloids like arsenic and cadmium from fertilisers and the surrounding soil, while sticky hairs on their leaves can gather particles from the air, including radioactive elements like polonium-210.

When the harvested leaves are cured and dried, compounds within them are converted into tobacco-specific nitrosamines (TSNAs), a class of well-known and intensely studied carcinogens. And when the smoker lights up, chemical reactions in the burning leaves fill the smoke with carbon monoxide, hydrogen cyanide and a cocktail of carcinogens – the infamous polycyclic aromatic hydrocarbons (PAHs), and vapour-borne “volatiles” like formaldehyde and benzene. As long as you’re burning plant matter and inhaling the smoke, you’ll get a lungful of carcinogens. “There’s no getting around that fact,” says Neal Benowitz, a pharmacologist from the University of California, San Francisco.

As always with toxicology, it’s the dose that makes the poison, and a laundry list of ingredients is a poor way of assessing a product’s true risk. But it’s clear that many of the substances in cigarette smoke, particularly the well-studied TSNAs, PAHs and volatiles, are found at significant levels in both the smoke and the bodies of smokers who inhale it. And, they cause similar patterns of DNA damage to those seen in actual tumors.

World's Leggiest Animal Found Near Silicon Valley

The leggiest creature on Earth lives in California. But it's not a movie star or a model. In fact, it's smaller than a human pinky finger. It's a 3-centimeter-long (1.2-inch) millipede with 750 legs.

First seen by scientists in 1928, Illacme plenipes—"the acme of plentiful legs"—keeps such a low profile that for the rest of the 20th century the species was thought to be extinct. Then University of Arizona entomologist Paul Marek spied one near Silicon Valley.

Marek and colleagues' new paper—published Wednesday by the journal ZooKeys—offers the first scientific description of Illacme plenipes, including insights into its strange anatomy.

For one thing, females have up to 750 legs, and males have more than 550. Most other millipede species have between 80 and 100 legs apiece, Marek said. For another thing, Illacme plenipes can spin silk from long hairs that cover its back, thereby creating its own "clothing."

"It's the coolest millipede I've ever heard about," Marek added.

Illacme plenipes has "kind of had a mythical status among millipede people," Marek said.

So in 2005, an intrigued Marek—then a doctoral student—began searching for the legendary invertebrate in a foggy 2.8-square-mile (7.3-square-kilometer) area outside San Francisco.

Over three years Marek and his team turned up 17 specimens, each clinging to sandstone boulders. Though they suspected more millipedes might be found, the team stopped collecting specimens in 2007, so as not to potentially deplete the species in the wild.

Because these burrowing arthropods live deep underground, their legs have adapted to include claws. Marek and other researchers hypothesize that these talons may help Illacme plenipes cling to subterranean rocks.

Other surprising anatomical features include massive antennae (relative to the scale of its body), which the millipede uses to feel its way through the dark; a jagged and translucent exoskeleton; and body hairs that produce a sort of silk that may help Illacme plenipes adhere to the undersides of boulders. And unlike in other millipedes, the mouth of this species is specifically structured for piercing and sucking plant tissues.

But Marek said Illacme plenipes does have at least one thing in common with other millipedes: a name that's "sort of a misnomer." No millipede has ever been known to have a thousand legs, he said (though he concedes that a species with that leg count may exist.

Now that Illacme plenipes has been rediscovered, how much longer does it have left?

Constant development in the area is destroying its habitat, Marek said. It would be a shame, he added, for this "bizarre" species to vanish again before we can learn more about it.