Milky Way Neighbouring Galaxies Get Amazing Portraits in UV

Nearly a million ultraviolet sources appear in this mosaic of the Large Magellanic Cloud, which was assembled from 2,200 images taken by Swift's Ultraviolet/Optical Telescope.

CREDIT: NASA/Swift/S. Immler (Goddard) and M. Siegel (Penn State)

Stitching together thousands of images, astronomers have created the most detailed ultraviolet light portraits of the Milky Way's two closest neighbors: the Large and Small Magellanic Clouds.

The stunning wide-field results give scientists a peek at the hot young stars of these satellite galaxies, which hover around the Milky Way less than 200,000 light years away.

The mosaics were assembled by astronomers at NASA and Pennsylvania State University using the space agency's Swift satellite. The images were unveiled last week at the American Astronomical Society (AAS) meeting in Indianapolis.

"Prior to these images, there were relatively few UV observations of these galaxies, and none at high resolution across such wide areas, so this project fills in a major missing piece of the scientific puzzle," Michael Siegel, lead scientist for Swift's Ultraviolet/Optical Telescope (UVOT), said in a statement.

The Large Magellanic Cloud (LMC) is one-tenth the size of the Milky Way, and the Small Magellanic Cloud (SMC) is just half that size. But since both are relatively close to our own galaxy, they appear quite large — too large to fit in UVOT's field of view. That's why researchers needed thousands of images to cover both galaxies.

The portrait of LMC, cobbled together from 2,200 snapshots, has a resolution of 160 megapixels and reveals about 1 million ultraviolet sources, according to a statement from NASA.

The 57-megapixel mosaic image of the SMC, meanwhile, is made of 656 individual images and shows about 250,000 ultraviolet sources.

Ultraviolet images allow astronomers to look at the hottest young stars and star-formation regions while blocking out older stars, mostly those more than 500 years old, which don't emit as much light at such higher energies.

One particularly dazzling piece of the LMC portrait shows the Tarantula nebula, where powerful stellar winds from newborn stars create a spider-like shape.

Aberdeen Scientists Find Link Between Light Deficiency and Multiple Sclerosis

Aberdeen scientists have found that artificial sunlight can have a “striking effect” in helping treat sufferers of diseases such as multiple sclerosis.

Researchers from Aberdeen University studied patients in the north of Scotland – which has the highest rate of MS in the UK - who were being treated during winter with artificial UV (ultraviolet)-B light therapy for skin diseases caused by their immune systems acting inappropriately.

The research - published in the Journal of Allergy and Clinical Immunology – shows how UV-B light boosts vitamin D, as well as cells in our body that are responsible for regulating or balancing the immune system. Vitamin D is made in our bodies by UV-B light from the sun.

Some studies have suggested a link between vitamin D deficiency and autoimmune diseases such as MS.

This possible link might also explain the increasing prevalence of autoimmune disease among those living far from the equator, where there are lower levels of winter sun.

Autoimmune diseases - like MS and type 1 diabetes - are diseases where the immune system mistakenly attacks the body’s own tissues or harmless substances that enter the body.

Dr Anthony Ormerod, clinical reader in dermatology at the university, said: “Our study shows that UV-B light, which mimics sunshine, can have a striking effect on the immune system of patients.

“We found that UV-B light boosted the production of vitamin D, and of regulatory T cells, which play an important role keeping our immune systems in check.

“Our findings have important implications for future interventions including the recommendations for healthy lifestyle and a possible role for phototherapy and/or vitamin D supplementation in the prevention or treatment of autoimmune and inflammatory diseases.

“While too much exposure to sunlight is harmful and increases skin cancer risk, these results suggest that subjects in our study would have some benefits from small amounts equivalent to summer exposure in the winter but more work needs to determine the role of sunlight and the role of supplementing the diet with vitamin D.”

Dr Helen Macdonald, senior lecturer in nutrition and translational musculoskeletal research at the university and chair of the National Osteoporosis Society Nutrition and Lifestyle forum, said: “There are risks associated with high levels of both therapies, so it is important that we get the balance right.

“We would also want to stress that we are not advocating sun bed use since this is not the same type of radiation produced by sun beds which already have well-documented health risks.

“The average dose of UV light that the volunteers received was the equivalent to sunlight exposure in Aberdeen over spring and summer and further work is required to determine if lower doses are effective.”

Professor Mark Vickers, chair in applied medicine at the university, added: “Ours is the first study to demonstrate in patients a cause and effect between UV light, vitamin D and systemic immune function in people.”