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Brown Dwarfs Under The Weather

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This post is not about short people of a particular colour, who are ill. This is about Brown Dwarfs, stars that are forever stuck in puberty – too massive to be a planet, and not massive enough to ignite nuclear fusion like “normal” stars that go on to live “star” lives (you know, burning hot and shining bright, possibly giving energy to planets / moons-full of life-forms, like our Sun).

A new study of 44 such brown dwarfs has revealed that, like planets, the brown dwarfs too have weather systems. For obvious reasons, the weather there is a bit “unearthly”. On Earth, the majority of storms and lightning are somehow related to water. But the brown dwarfs are far too hot to have any kind of water-based weather. Yet, they still do have clouds, and storms, and lightning, and you get the picture.

An artist’s rendition of the weather on a brown dwarf. Credit: NASA/JPL-Caltech/University of Western Ontario/Stony Brook University

(See, I did say “you get the picture”. Get it? Please don’t kill me.)

So what are these storms made of then? The clouds and the rain they rain are believed to be made of hot sand, salts, and even molten iron! To give you some idea, iron melts at 2,800°F (1,538°C). So, imagine a real hot, burning furnace, and add lightning to it. I think this image fits the context.

So how did astronomers see such violent weather on these “failed stars”? Well, clouds moving across the surface of a planet, or star in this case, result in variation of the brightness of the light emanating from that surface. In the case of planets, it is the light that they reflect (coming from their star), while in the case of these brown dwarfs, it’s the light they generate themselves. Even though the light from the dwarfs is not very bright compared to normal stars, our instruments can still pick up the variations in it, as clouds block some of it for some time, and then move to some other part of the surface, leading to changes in brightness over time.

Although out of the 44 brown dwarfs under study, only about half showed direct evidence for these brightness variations, scientists still think most or all of the dwarfs must be “weathered”. This is because it’s likely that not all of them were aligned perfectly with the line of sight from Earth – some of them would be aligned such that the storms would either be hidden or always be in view; for detection of weather patterns, the key is change in brightness. For example, if a storm were to always cover the surface of the dwarf, the light from the dwarf would be reduced. But since we never get to see that same dwarf being any brighter, we can’t say whether this is because it’s covered by a storm, or because it’s just less bright by itself (by not being massive enough, and hence, by not producing enough energy).

So, the point is, we can assume that almost all brown dwarfs weather such weather.

And it turns out that Santa was extra pleased with the astronomers’ efforts! In addition to the above, they also discovered that some of these dwarfs rotated more slowly than any previously observed! They have a couple of theories as to why that might be – different formation histories, undetected planets tugging on the dwarfs (gravitationally) and slowing them down over time, etc. As always, they need more observations and data to say anything conclusively.

The observations were made with the Spitzer Space Telescope, which takes images in the infrared spectrum and was ideally suited for the job. This was in part because of the thermal-imaging capabilities (as used by night-vision goggles, and also by the “predator” in the Arnold Schwarzenegger movie, Predator), and partly because of its orbit – it orbits the Sun, instead of the Earth. This allows it to make observations of such faint stars, which would otherwise be next to impossible to see, because of the background glare from the Earth.

All this information not only helps the astronomers understand brown dwarfs better, but also their little cousins, the gas giants, like Jupiter. Perhaps these observations may one day be able to explain what’s really going on with Jupiter’s Great Red Spot, which has been in existence for over 400 years!

Great Red Spot, as spotted by Voyager 1 in late 1970s. Credit: NASA (http://photojournal.jpl.nasa.gov/catalog/PIA00014) [Public domain], via Wikimedia Commons

 And you thought the recent “polar vortex” was bad!

 

— Shivang Gupta

Sources:

– News release

Wikipedia

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Words

Sometimes there just aren’t any words that can do justice to what one wants to say; or perhaps there are, but one simply doesn’t know them.

Either way, I’ve often found myself being in that situation because of the beauty of our universe.

It’s a bitter-sweet thing – on the one hand, not being able to define that feeling of raw wonder in my own way feels like something is amiss, but on the other hand, just to be able to feel that thing in the first place is a privilege.

 

Three Galaxies and a Comet

Three Galaxies and a Comet (credit: Miloslav Druckmuller, Brno University of Technology)

 

Pictured above – The Milky Way galaxy, along with the Large and Small Magellanic Clouds (small, satellite galaxies of the Milky Way), as well as Comet McNaught.

Click on the image for more details.

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Is it a fish? Is it a cow? No, it’s a supernova nebula!!

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The supernova remnant nebula W50 has been officially nicknamed the “Manatee Nebula”, January 19, 2013.

Credit: NRAO/AUI/NSF, K. Golap, M. Goss; NASA’s Wide Field Survey Explorer (WISE).

When the National Radio Astronomy Observatory (NRAO), observed the nebula, situated 18,000 light-years away, at radio wavelengths using the Very Large Array (VLA) telescope, it was found that the nebula had a remarkable resemblance to the Manatee, an endangered species of marine mammals, also popularly known as “sea-cows”.

Check out the official press release, for a (totally awesome) side-by-side comparison of the nebula and the “cow”.

The nebula is 700 light-years across, and together with its resemblance to the manatee, truly becomes a giant “cow in the sky”.

 

History of W50

Long, loooong ago (or very, veeeery recently – depending on whether you talk in terms of your lifetime, or the universe’s), a star in the star system SS 433 went supernova, leaving SS 433 an eclipsing, X-ray binary system. As it turns out, SS 433 also happens to be a micro-quasar.

Coming back to the original language of this blog, which is English, an “eclipsing, X-ray binary” simply means that the system is composed of two stars, which appear to eclipse each other (as viewed from the Earth), and that at least one of the stars emits most of its energy in the form of X-rays. And a micro-quasar (a smaller cousin of the quasar), is a star that weighs about a few times the Sun’s mass, and emits most of its energy in the form of high-frequency, short-wavelength X-rays. The star in this case could be a white dwarf, a black hole or a neutron star.

In the case of SS 433, the more massive, primary star is most likely a black hole micro-quasar (the chance that it is a neutron star instead is small). It also happens to be the first discovered micro-quasar! The other, less massive, secondary star is likely an A-type star, as per the scheme of stellar classification.

The nebula that the supernova explosion left behind is what came to be known as W50 some 20,000 years later.

Feast your eyes on this video of the Manatee Nebula, and accompanying simulation of SS 433!

 

To conclude, I have rambled on about this tiny bit of information, and you have (hopefully!) been generous enough to read it so far, but in case you are wondering “why should I care?”, I have an answer for you. You should care because you are a part of this universe!

Today there’s a cow in the sky.

Who knows, maybe tomorrow pigs will fly!

 

Official press release here.

And to give credit where it’s due, this is the initial post that brought the news to me in the first place and resulted in this blog.

Pareidolia in the Carina Nebula

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Pareidolia – Observing imagined patterns, shapes or meaning where none exists.

Hubble Heritage is holding a competition on their Facebook page, titled Creative Challenge. In the contest, contestants are given an image and they must use their imagination and creativity to show what they see in that image.

This month’s Creative Challenge shows us an image of the Carina Nebula:

Carina Nebula

Do you see anything here?

I did. Here‘s what I saw, titled Cosmic Collision (Not posting the image itself, so as not to ruin anybody else’s imagination of what this beautiful image might contain). And here‘s a top/bottom comparison of the two images.

To check out what others are seeing in this nebula, please check out Hubble Heritage’s Facebook page.

And as I pointed out earlier, this is a contest! And the winner of that contest would be determined by how many likes his/her pareidolia image gets. So if you like what I have done here, do remember to ‘Like’ my image of Cosmic Collision on Facebook here. Each ‘Like’ that the image gets brings it closer to winning!

Above all, come and be a part of this contest! Let your imagination run wild!

Do you like my image of the Cosmic Collision? Let me know in the comments and in this poll: