skaltezon

Post information about any aspect of the observed physical universe that interests you.
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Blast from the past

Images from the Swift Xray Telescope, a satellite launched by NASA in 2004,
indicate that xrays from the presumed star-swallower Swift J1644+57 would
have been emitted 3.9 billion years ago, theoretically from around the base
of an associated relativistic jet. Although the news is just arriving, it's an ancient event.

NASA - Researchers Detail How A Distant Black Hole Devoured A Star



Relativistic jet - Wikipedia, the free encyclopedia


Sagittarius A* -- 150,000x closer and 4x bigger

Our own galaxy's supermassive black hole, called Sagittarius A*, was discovered in the radio spectrum
in 1974 by astronomers Balick and Brown at the National Radio Astronomy Observatory.

Measurements reveal a sphere assumed to be the event horizon concealing a mass exceeding 4 million suns.

Sagittarius A* - Wikipedia, the free encyclopedia

2002 image of Sagittarius A* (Sgr A*) obtained via the Chandra X-ray Observatory, a satellite launched by NASA in 1999.



You can't see Sgr A* in this wide-field image, but it underlies the brightest spot shown. Huge lobes of 20 million-degree Centigrade gas that extend over dozens of light years on either side of it (the red loops at 2 and 7 o'clock) indicate that enormous explosions occurred several times over the last ten thousand years.

During the two-week observation period, Sgr A* flared up in X-ray intensity half a dozen or more times. But even during the flares the intensity of the X-ray emission from the vicinity of the black hole was relatively weak, suggesting that Sgr A* has cleared the vicinity of most infalling matter. Three young stars (not shown here) orbit the object rapidly, just out of swallowing range.

Chandra :: Photo Album :: Sagittarius A* :: 06 Jan 03

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Burning Down

So is this a thread for discussion of astrophysics, or just for posting random articles?

VEGANGELICA

Nice X-ray picture of our galaxy's supermassive black hole, Sgr A*!

I am interested in the use of different wavelengths of radiation to create striking visual images that increase astrophysicists' understanding of the universe. I like such images because they remind me that our human senses do not let us perceive all of reality.

For example, observe the following two pictures courtesy of the NASA Jet Propulsion Laboratory website I was looking at just last week for fun:
Space Images Wallpaper Search: The Universe - NASA Jet Propulsion Laboratory.

If these pictures used only visible light, then they would leave us blind to much of the complexity and grandeur of these celestial events and bodies:

Infrared light image of "Mountains" where stars are being born, viewed by NASA's Spitzer Space Telescope.
Infrared light penetrates dust, while visible light is blocked by it, so this infrared image looks very different than the one made using visible light:



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Cartwheel Galaxy, seen by detecting ultraviolet (shown as blue), visible (shown as green), infrared (shown as red), and X-ray (shown as purple) radiation:

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skaltezon

Nice photos. The "Mountains of Creation" region is in Casseopeia. We also use infrared and radio telescopes to study the Milky Way's galactic center, since gas and dust obscures it in visible wavelengths.

RVCA

I'm just curious, what's your background in astrophysics? Have you studied it, or are you just a fan?

skaltezon

Post information about any aspect of the observed physical universe that interests you, or comment on what someone else has posted.

VEGANGELICA

I hope you include flowers as part of the observed physical universe, because my interest in the perception of electromagnetic radiation actually began with them.

If we zoom in closely on our Milky Way galaxy, to our Solar System, to our Earth, then we come to many flowers, each like a little black hole, absorbing ultraviolet light to create interesting patterns that only creatures with vision in the ultraviolet part of the spectrum can see.

I was excited when I first learned long ago of this great example of other animals' ability to do and perceive things that we humans cannot.

Observe the two pictures below showing Oenothera biennis L. The flower in visible light just looks bland yellow to us. Yet under ultraviolet light, a striking center spot with radiating lines appears, presumably helping pollinators home in on the important nectar and pollen in the middle of the blossom and helping the plant ward off flower predators (http://www.news.cornell.edu/releases...owers.hrs.html).

Ultraviolet Flowers: Oenothera biennis

Oenothera biennis L. flower in visible light:


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Oenothera biennis L. flower in ultraviolet light, showing patterns that a bee would perceive. No one...except the bee ...knows what internal color or mental image a bee perceives when it views the flower.

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skaltezon

That's too much zooming. I'm looking for objects, processes and energies that lie beyond our planet's atmosphere, please.

VEGANGELICA

Okay, I'll zoom out a little.

Solar flares. I like those. I remember when I first realized that our sun is a star similar to all the other stars we see in the universe, and the sun isn't particularly "friendly" or "happy." It looks so benign and warm, albeit very bright, to our naked eye from our vantage point, but what is really going on in that massive, seething fusion-ball is this:


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Here's a more recent, closer look from a rocket telescope. "Close-up images reveal an active surface with coronal loops emerging and disappearing all over the Sun's surface and can span a length of about 250,000 miles, or about 30 times the diameter of Earth."
Rocket telescope gets closest look at the Sun

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skaltezon

That's an enormous loop of plasma in that first image -- made me think of coronal mass ejections (CMEs), where huge quantities of matter and electromagnetic radiation are released into space. A typical CME could be a billion tons of plasma traveling at 1.8 million kph, consisting primarily of electrons and protons with small quantities of heavier elements such as helium, oxygen, and even iron. The frequency of ejections depends on the phase of the solar cycle: from about one every other day near the solar minimum to 5–6 per day near the solar maximum.

When the ejection is directed towards the Earth, the shock wave of the traveling mass causes a geomagnetic storm that directs trillion-watt power discharges into the Earth's upper atmosphere. It can damage satellites and pose a radiation hazard to astronauts and jet passengers.

Coronal mass ejection - Wikipedia, the free encyclopedia