Comment

Comment by Dr. Krishna Kumari Challa on April 8, 2024 at 9:12am

Enigmatic white dwarfs

Central to the spectacle of T Coronae Borealis is the white dwarf, a stellar remnant that offers profound insights into the life cycles of stars.

White dwarfs are the end products of stars that originally had masses up to eight times that of the Sun but ended their lives in a relatively peaceful manner, without exploding as supernovae.

These stellar cores are fascinating for several reasons:

• Density and Composition: Despite their diminutive size, white dwarfs are incredibly dense. Their mass is comparable to that of the Sun, but they have a volume similar to Earth’s. This high density arises because the matter within them is in a degenerate state, where electrons are packed closely together.
• Cooling Process: After their formation, white dwarfs embark on a long cooling process. They start out extremely hot but gradually radiate away their heat over billions of years, eventually fading into black dwarfs — theoretical objects that have not yet been observed because the universe is not old enough.
• Limiting Mass: The Chandrasekhar limit, approximately 1.4 times the mass of the Sun, defines the maximum mass a white dwarf can have. Beyond this limit, the star would collapse under its own gravity to form a neutron star or a black hole.

Window into cosmic evolution

In summary, the study of T Coronae Borealis and white dwarfs opens a window into the complex processes governing stellar evolution.

Part3

Comment by Dr. Krishna Kumari Challa on April 8, 2024 at 9:12am

Key differences between novae and supernovae

Scale and Energy

The most striking difference lies in their scale and the energy released. Supernovae are among the universe’s most energetic events, outshining entire galaxies and releasing vast amounts of energy. Novae, while still bright and powerful, are far less energetic and only cause a temporary increase in brightness.

Frequency and Visibility

Supernovae are relatively rare events, occurring about once every 50 years in a galaxy the size of the Milky Way. Novae, on the other hand, are more common, with several occurring in our galaxy each year. Despite their rarity, supernovae can often be seen from greater distances due to their immense brightness.

Part 2

https://www.earth.com/news/t-coronae-borealis-blaze-star-explosion-...

Comment by Dr. Krishna Kumari Challa on April 8, 2024 at 9:09am

Differences between nova and supernova explosions

The cosmos is a stage for some of the most spectacular and powerful events known to science. Among these, nova and supernova explosions stand out for their brilliance and the fundamental roles they play in the universe’s lifecycle.

Despite the similarity in their names, novae and supernovae differ vastly in their origins, mechanisms, and consequences. This article demystifies these cosmic phenomena, highlighting their distinct characteristics.

What is a nova?

As discussed above, a nova occurs in a binary star system, where a white dwarf and a companion star orbit closely. The white dwarf, a dense remnant of a star that has exhausted its nuclear fuel, pulls material — primarily hydrogen — from its companion.

This material accumulates on the white dwarf’s surface, eventually igniting in a thermonuclear explosion. The explosion causes the white dwarf to brighten significantly, but it does not result in the star’s destruction. Instead, the process may repeat if the white dwarf continues to accrete material.

What is a supernova?

In contrast, a supernova is a cataclysmic event marking the death of a star. Supernovae can occur in one of two primary ways:

Core-Collapse Supernova: This type happens at the end of a massive star’s life cycle. When the star’s core runs out of nuclear fuel, it can no longer support the outer layers against gravity. The core collapses, resulting in a massive explosion that obliterates the star.

Type Ia Supernova: This type involves a binary system where a white dwarf accretes material from a companion star, similar to a nova. However, in this case, the white dwarf reaches a critical mass (Chandrasekhar limit), leading to a runaway nuclear reaction that completely destroys the white dwarf.

Part 1

Comment by Dr. Krishna Kumari Challa on April 8, 2024 at 9:08am

Huge star explosion to appear in sky in once-in-a-lifetime event

Sometime between now and September, a massive explosion 3,000 light years from Earth will flare up in the night sky, giving amateur astronomers a once-in-a-lifetime chance to witness this space oddity.

The binary star system in the constellation Corona Borealis—"northern crown"—is normally too dim to see with the naked eye.

But every 80 years or so, exchanges between its two stars, which are locked in a deadly embrace, spark a runaway nuclear explosion.

The light from the blast travels through the cosmos and makes it appear as if a new star—as bright as the North Star, according to NASA—has suddenly just popped up in our night sky for a few days.

It will be at least the third time that humans have witnessed this event, which was first discovered by Irish polymath John Birmingham in 1866, then reappeared in 1946.

There are only around 10 recurring novas in the Milky Way and surrounding galaxies. Normal novas explode "maybe every 100,000 years". But recurrent novas repeat their outbursts on a human timeline because of a peculiar relationship between their two stars.

One is a cool dying star called a red giant, which has burnt through its hydrogen and has hugely expanded—a fate that is awaiting our own sun in around five billion years.

The other is a white dwarf, a later stage in the death of a star, after all the atmosphere has blown away and only the incredibly dense core remains.

Their size disparity is so huge that it takes T Coronae Borealis's white dwarf 227 days to orbit its red giant. 

The two are so close that matter being ejected by the red giant collects near the surface of the white dwarf.

Once the mass roughly of Earth has built up on the white dwarf—which takes around 80 years—it heats up enough to kickstart a runaway thermonuclear reaction. This ends up in a "big explosion and within a few seconds the temperature goes up 100-200 million degrees Celsius". 

But you do not need  advanced technology to witness this rare event—whenever it may happen. You simply have to go out and look in the direction of the Corona Borealis .... and you can see it with your own naked eyes!

This particular star explosion is unique for its brief yet intense display, completing its cycle in merely a week. 

Source: AFP and other news agencies

Comment by Dr. Krishna Kumari Challa on April 6, 2024 at 11:12am

Scientists examined plaque samples from patients who had undergone surgery to clean out their carotid arteries, blood vessels in the neck that carry blood to the brain. They found that more than half of patients had evidence of at least one type of plastic.

These patients’ plaques all contained polyethylene, a ubiquitous material used in everything from cling wrap to cutting boards. And in 12 percent of the patients, scientists also found polyvinyl chloride, or PVC. 

Of 150 people with evidence of these plastics, 30 died or experienced a nonfatal stroke or heart attack within roughly the next three years. That’s compared to eight out of 107 people whose plaques appeared to be plastic-free, the team reports.

It’s too early to say whether microplastics in the arteries can cause heart attacks

It’s possible that plastics inside the arteries drive inflammation, further kindling cardiovascular disease. Plaques embedded with plastic, for instance, tended to contain more inflammatory molecules than plastic-free plaques, the research  team found.

The researchers did not prove that microplastics are harmful, scientists say. They simply exposed a link between plastics in plaques and poor outcomes in patients.

The plaque study offers yet another reason why it’s probably a good idea to reduce plastic use 

R. Marfella et al. Microplastics and nanoplastics in atheromas and cardiovascular events. The New England Journal of Medicine. Published online March 7, 2024. doi: 10.1056/NEJMoa2309822.

M. A. Garcia et al. Quantitation and identification of microplastics accumulation in hu... Toxicological Sciences. Published online February 17, 2024. doi:10.1093/toxsci/kfae021.

Part 2

Comment by Dr. Krishna Kumari Challa on April 6, 2024 at 11:09am

A new study has linked microplastics to heart attacks and strokes. Here’s what we know 

The results have renewed concerns about plastics’ potential effects on human health

Tiny flecks of plastic inside in the arteries may ramp up the risks of cardiovascular disease.

An analysis of artery-clogging plaques in 257 patients found that the presence of these microplastics was associated with a roughly quadr..., researchers report March 7 in the New England Journal of Medicine. 

The extent of that enhanced risk is “stunning,” say the researchers. Because  “very, very, very few things have that much of a risk.”

The study has gained attention worldwide and renewed concerns about the effects of plastics on human health. It’s also one of a growing number of reports that have found microscopic particles of plastic inside our bodies’ tissues, including the lungs, liver and blood.

Plastic is everywhere and enters our body through multiple routes 

When plastic toys, pipes, food containers and other objects inevitably break down over time, they can shed infinitesimal particles into our environment. Scientists have already documented how broadly these plastic smithereens have scattered.

Particles speckle even extreme locations, from the depths of the ocean to nearly the peak of Mount Everest.  Microplastics, which are smaller than 5 millimeters (about the size of a peppercorn) and nanoplastics, which are roughly one five-thousandth that size, can get into our water, accumulate in soil and waft along whispers of wind.

These specks of plastic pollution can travel into our bodies via food and drink, the air we breathe and even directly through the skin. And our exposure to microplastics will only go up, say experts.

Part 1

Comment by Dr. Krishna Kumari Challa on April 6, 2024 at 10:58am

Bird flu has infected a person after spreading to cows

A strain of avian influenza that has likely sickened and killed millions of birds around the globe has popped up in an unexpected species: Cows.

On April 1, the U.S. Department of Agriculture confirmed that cattle on a farm in New Mexico had tested positive for a strain of bird flu called H5N1. The news followed a March 25 announcement that officials had detected the virus on two dairy farms in Kansas and two Texas farms. The virus was also detected in a Michigan herd that had recently received cows from Texas, the USDA reported on March 29. Five additional herds in Texas have tested positive, and an outbreak in Idaho is presumed to have been caused by H5N1.

A person exposed to cattle on one of those Texas farms has tested positive too, becoming only the second person in the United States ever documented to be infected with H5N1, the U.S. Centers for Disease Control and Prevention reported April 1. The individual is being treated with an antiviral drug for a single symptom, eye redness. It’s unclear how the cows were infected, although consuming wild bird excrement is a possibility. The person was probably infected while in close contact with the cows. Most people fall ill with H5N1 only after close contact with infected animals, typically poultry, and these infections can be mild to deadly. Right now, the CDC considers H5N1’s risk to people to be low. But milk from infected cows should be thrown out before reaching our food supply, the USDA says. Pasteurization would also kill the virus, so it should not spread through the country’s milk, the agency said.

https://www.cdc.gov/media/releases/2024/p0401-avian-flu.html

Comment by Dr. Krishna Kumari Challa on April 6, 2024 at 9:00am

Europe and North America had higher proportions of human-tolerant bird species than Latin America and Africa did. Europe has a long history of environmental impacts spanning millennia, which, according to the researchers, may have resulted in historical disappearances of sensitive species and also in a long time frame for the remaining species to adapt to the gradually changing landscapes.

The researchers quantified tolerance to breeding in human-dominated environments for 6,000 bird species. The data on birds originated from citizen science observations from the eBird project from 2013–2021. The data on the extent of human impact was the Human Footprint Index that summarizes the combined pressures of built environments, human population density, night-time lights, agriculture and roads.

Emma‐Liina Marjakangas et al, Bird species' tolerance to human pressures and associations with population change, Global Ecology and Biogeography (2024). DOI: 10.1111/geb.13816

Part 2

Comment by Dr. Krishna Kumari Challa on April 6, 2024 at 8:59am

Four in five bird species cannot tolerate intense human pressures, data show

Currently 14% of the world's 11,000 bird species are threatened with extinction. A new study assessed the populations of bird species across a spectrum of landscapes from pristine habitats to human-dominated environments.

Threatened species, and species with declining populations, are less tolerant to breeding in human-dominated habitats. For example, the Fern Wren, a species occurring only in tropical forests of northeastern Australia, is endangered, has a declining population and a very low tolerance to any human pressure, say the researchers. However, not all species are as sensitive to living alongside humans. Some species can tolerate even the most intense human pressures on all continents. Common Swifts are an example of such species that can be found breeding in urban areas all around the world.
Following the UN's Kunming–Montreal Global Biodiversity Framework, goals have been set to protect 30% of the Earth's land for conservation, but not much of that percentage will be pristine habitat.
This new study enables us to identify species that are particularly sensitive to human activity and need more protected habitats to thrive, for example the Great Snipe in Europe, the Nkulengu Rail in Africa and the Hume's Lark in Asia. Conservation action to protect or restore habitat can then be targeted towards the species and locations that need it most.
Part 1

Comment by Dr. Krishna Kumari Challa on April 5, 2024 at 12:13pm

mRNA shows promise beyond vaccines
A therapy that extends mRNA technology beyond vaccines has shown early success in treating a rare genetic disease, propionic acidaemia, that prevents people from processing certain nutrients. The treatment — made by US pharma company Moderna, and known as mRNA-3927 — gives those treated a working copy of the instructions needed to make an enzyme that is missing in people with the disease. In a small clinical trial, half of the participants receiving the therapy saw their risk of life-threatening episodes decrease by 70-80%. But the drug also produced side effects and required frequent infusions.

https://www.nature.com/articles/d41586-024-00954-4?utm_source=Live+...

• ‹ Previous
• 1
• …
• 219
• 220
• 221
• 222
• 223
• …
• 1053
• Next ›
• Page