New Night Sky Episode

Written by The Night Sky Guy on January 16, 2010 – 11:52 am -

If you missed it last night here is my latest episode where we talk about tracking down Orion constellation and its most celebrated star – Betelgeuse. Just don’t say that name three times 😉

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Most Detailed Photo of Star Ever

Written by The Night Sky Guy on January 13, 2010 – 10:39 am -

I remember when I started out stargazing through a telescope when I was a kid and a seasoned stargazer told me to never expect to be able to zoom into any star in the sky and see detail. He told me that no matter how much power, or how big a telescope I had, it was impossible to see any detail on a star- and that it would always remain a point of light through any telescope. How things have changed…

The surface of Betelgeuse in near infrared; Copyright 2010 Haubois / Perrin (LESIA, Observatoire de Paris)

Using the technique called interferometry – where the light from different telescopes are combined into one superdetailed image (image above) – a team of astronomers has obtained for the first time a snapshot of the actual surface of a distant star outside of our solar system – the surface of the red supergiant Betelgeuse, in the constellation of Orion. The image reveals the presence of two giant bright spots, whose size is equivalent to the Earth-Sun distance: they cover a large fraction of the surface. It is a first strong and direct indication of the presence of the convection phenomenon, transport of heat by moving matter, in a star other than the Sun. This result allows us to better understand the structure and the evolution of supergiants.

Betelgeuse is a red supergiant located in the constellation of Orion. This star is quite different from our Sun: 600 times larger in dimension, it radiates approximately 100,000 times more energy.

You can easily find 430 light year distant Betelgeuse using nothing more than your unaided eyes tonight dominating the southern evening sky. It is one of the brightest stars of winterand is the lead star in seasonal landmark constellation Orion – making the hunter’s left shoulder.

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Monster Star Comes into Focus

Written by The Night Sky Guy on July 29, 2009 – 9:13 am -

Stars are so far away that most telescopes, even some of the largest, cannot resolve them into disks. They simply appear as a point of light. Now all that is changing, thanks to a new technique where the power of three giant telescopes can be combined as one.  Now astronomers have taken the sharpest view of a dying mammoth star ever made (see image on right).  Even with Earth’s turbulent, image-distorting atmosphere in the way, the resolution of the red giant Betelgeuse is as fine as 37 milliarcseconds, which is roughly the size of a tennis ball on the International Space Station (ISS), as seen from the ground.

For the first time they could show, how the gas is moving in different areas over the surface of a distant star. This latest news on the famous bright star, Betelgeuse, in the constellation Orion, comes on the heels of the discovery last month that the same star is skrinking in size. This new accomplishment was made possible by combining three 1.8 m telescopes as an interferometer, giving the astronomers the resolving power of a virtual, gigantic 48 m telescope. Using the ESO VLT Interferometer in Chile, they discovered that the gas in the dying star’s atmosphere is vigorously moving up and down, but the size of such “bubbles” is as large as the star itself. These colossal bubbles are a key for pushing material out of the star’s atmosphere into space, before the star explodes as a supernova.

Artists impression, showing how a vast amount of material is flung out from Betelgeuse into space.

Artist's impression, showing how a vast amount of material is flung out from Betelgeuse into space.

Betelgeuse in Orion

Betelgeuse in Orion

When one looks up the clear night sky in winter, it is easy to spot a bright, orange star on the shoulder of the constellation Orion (the Hunter) even in light-flooded big cities. That is Betelgeuse. It is a giant star, which is so huge as to almost reach the orbit of Jupiter, swallowing the inner planets Mercury, Venus, Earth, and Mars, when placed at the center of the solar system. It is also glaringly bright, emitting 100 000 times more light than the Sun. Betelgeuse is a so-called red supergiant and approaching the end of its short life of several million years. Red supergiants shed a large amount of material made of various molecules and dust, which are recycled for the next generation of stars and planets possibly like the Earth. As a matter of fact, Betelgeuse is losing material equivalent to the Earth’s mass every year.

The death of the mammoth star, which is expected in the next few thousand to hundred thousand years, will be accompanied by cosmic fireworks known as a supernova like the famous SN1987A. However, as Betelgeuse is much closer to the Earth than SN1987A, the supernova can be clearly seen with the unaided eye, even in daylight.

– Adapted from material taken from a news announcement by the Max-Planck-Institut for Radio Astronomy

click image to enlarge

click image to enlarge

Doorstep Astronomy: You can check out Betelgeuse and its host constellation Orion in the early morning sky. Look towards the eastern horizon about a half hour before local sunrise and you should be able to make out the belt of three stars and the distinct orange-hued Betelgeuse sitting to their upper left. If the glare from the dawn is giving you a hard time finding the red giant, then use the super-bright, star-like Venus (brightest star in the sky) and just scan over to its right side and you should see 429 light year distant Betelgeuse stand out.




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Giant Star in Sky Shrinking

Written by The Night Sky Guy on June 9, 2009 – 4:16 pm -

The red supergiant star Betelgeuse, the bright reddish star in the constellation Orion, has steadily shrunk over the past 15 years, according to University of California, Berkeley, researchers. Long-term monitoring shows that Betelgeuse (bet’ el juz), which is so big that in our solar system it would reach to the orbit of Jupiter, has shrunk in diameter by more than 15 percent since 1993.
Since Betelgeuse’s radius is about five astronomical units, or five times the radius of Earth’s orbit, that means the star’s radius has shrunk by a distance equal to the orbit of Venus. 

Hubbles View of Betelgeuses disk

Hubble's View of Betelgeuse's disk



Despite Betelgeuse’s diminished size, astronomers pointed out that its visible brightness, or magnitude, has shown no significant dimming over the past 15 years.

“But we do not know why the star is shrinking,” one of the researchers said. “Considering all that we know about galaxies and the distant universe,there are still lots of things we don’t know about stars, including what happens as red giants near the ends of their lives.”

Courtesy of 214th Meeting of the American Astronomical Society in Pasedena, California

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