Ooo, That’s Pretty Cool

Ooo, that’s pretty cool

Also - a nice little teaser - we’ll be covering brown dwarfs in the next chapter of the Life of a Star!

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ASTRONOMERS FIND JUPITER-LIKE CLOUD BANDS ON CLOSEST BROWN DWARF

A team of astronomers has discovered that the closest known brown dwarf, Luhman 16A, shows signs of cloud bands similar to those seen on Jupiter and Saturn. This is the first time scientists have used the technique of polarimetry to determine the properties of atmospheric clouds outside of the solar system, or exoclouds.

Brown dwarfs are objects heavier than planets but lighter than stars, and typically have 13 to 80 times the mass of Jupiter. Luhman 16A is part of a binary system containing a second brown dwarf, Luhman 16B. At a distance of 6.5 light-years, it’s the third closest system to our Sun after Alpha Centauri and Barnard’s Star. Both brown dwarfs weigh about 30 times as much as Jupiter.

Despite the fact that Luhman 16A and 16B have similar masses and temperatures (about 1,900°F, or 1,000°C), and presumably formed at the same time, they show markedly different weather. Luhman 16B shows no sign of stationary cloud bands, instead exhibiting evidence of more irregular, patchy clouds. Luhman 16B therefore has noticeable brightness variations as a result of its cloudy features, unlike Luhman 16A.

“Like Earth and Venus, these objects are twins with very different weather,” said Julien Girard of the Space Telescope Science Institute in Baltimore, Maryland, a member of the discovery team. “It can rain things like silicates or ammonia. It’s pretty awful weather, actually.”

The researchers used an instrument on the Very Large Telescope in Chile to study polarized light from the Luhman 16 system. Polarization is a property of light that represents the direction that the light wave oscillates. Polarized sunglasses block out one direction of polarization to reduce glare and improve contrast.

“Instead of trying to block out that glare, we’re trying to measure it,” explained lead author Max Millar-Blanchaer of the California Institute of Technology (Caltech) in Pasadena, California.

When light is reflected off of particles, such as cloud droplets, it can favor a certain angle of polarization. By measuring the preferred polarization of light from a distant system, astronomers can deduce the presence of clouds without directly resolving either brown dwarf’s cloud structure.

“Even from light-years away, we can use polarization to determine what the light encountered along its path,” added Girard.

“To determine what the light encountered on its way we compared observations against models with different properties: brown dwarf atmospheres with solid cloud decks, striped cloud bands, and even brown dwarfs that are oblate due to their fast rotation. We found that only models of atmospheres with cloud bands could match our observations of Luhman 16A,” explained Theodora Karalidi of the University of Central Florida in Orlando, Florida, a member of the discovery team.

The polarimetry technique isn’t limited to brown dwarfs. It can also be applied to exoplanets orbiting distant stars. The atmospheres of hot, gas giant exoplanets are similar to those of brown dwarfs. Although measuring a polarization signal from exoplanets will be more challenging, due to their relative faintness and proximity to their star, the information gained from brown dwarfs can potentially inform those future studies.

NASA’s upcoming James Webb Space Telescope would be able to study systems like Luhman 16 to look for signs of brightness variations in infrared light that are indicative of cloud features. NASA’s Wide Field Infrared Survey Telescope (WFIRST) will be equipped with a coronagraph instrument that can conduct polarimetry, and may be able to detect giant exoplanets in reflected light and eventual signs of clouds in their atmospheres.

IMAGE….Astronomers have found evidence for a striped pattern of clouds on the brown dwarf called Luhman 16A, as illustrated here in this artist’s concept. The bands of clouds were inferred using a technique called polarimetry, in which polarized light is measured from an astrophysical object much like polarized sunglasses are used to block out glare. This is the first time that polarimetry has been used to measure cloud patterns on a brown dwarf. The red object in the background is Luhman 16B, the partner brown dwarf to Luhman 16A. Together, this pair is the closest brown dwarf system to Earth at 6.5 light-years away. CREDITS: Caltech/R. Hurt (IPAC)

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star jupiter browndwarf

Galaxies: Types and morphology

A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. Galaxies range in size from dwarfs with just a few hundred million (108) stars to giants with one hundred trillion (1014) stars, each orbiting its galaxy’s center of mass.

Galaxies come in three main types: ellipticals, spirals, and irregulars. A slightly more extensive description of galaxy types based on their appearance is given by the Hubble sequence.

Since the Hubble sequence is entirely based upon visual morphological type (shape), it may miss certain important characteristics of galaxies such as star formation rate in starburst galaxies and activity in the cores of active galaxies.

Ellipticals

The Hubble classification system rates elliptical galaxies on the basis of their ellipticity, ranging from E0, being nearly spherical, up to E7, which is highly elongated. These galaxies have an ellipsoidal profile, giving them an elliptical appearance regardless of the viewing angle. Their appearance shows little structure and they typically have relatively little interstellar matter. Consequently, these galaxies also have a low portion of open clusters and a reduced rate of new star formation. Instead they are dominated by generally older, more evolved stars that are orbiting the common center of gravity in random directions.

Spirals

Spiral galaxies resemble spiraling pinwheels. Though the stars and other visible material contained in such a galaxy lie mostly on a plane, the majority of mass in spiral galaxies exists in a roughly spherical halo of dark matter that extends beyond the visible component, as demonstrated by the universal rotation curve concept.

Spiral galaxies consist of a rotating disk of stars and interstellar medium, along with a central bulge of generally older stars. Extending outward from the bulge are relatively bright arms. In the Hubble classification scheme, spiral galaxies are listed as type S, followed by a letter (a, b, or c) that indicates the degree of tightness of the spiral arms and the size of the central bulge.

Barred spiral galaxy

A majority of spiral galaxies, including our own Milky Way galaxy, have a linear, bar-shaped band of stars that extends outward to either side of the core, then merges into the spiral arm structure. In the Hubble classification scheme, these are designated by an SB, followed by a lower-case letter (a, b or c) that indicates the form of the spiral arms (in the same manner as the categorization of normal spiral galaxies).

Ring galaxy

A ring galaxy is a galaxy with a circle-like appearance. Hoag’s Object, discovered by Art Hoag in 1950, is an example of a ring galaxy. The ring contains many massive, relatively young blue stars, which are extremely bright. The central region contains relatively little luminous matter. Some astronomers believe that ring galaxies are formed when a smaller galaxy passes through the center of a larger galaxy. Because most of a galaxy consists of empty space, this “collision” rarely results in any actual collisions between stars.

Lenticular galaxy

A lenticular galaxy (denoted S0) is a type of galaxy intermediate between an elliptical (denoted E) and a spiral galaxy in galaxy morphological classification schemes. They contain large-scale discs but they do not have large-scale spiral arms. Lenticular galaxies are disc galaxies that have used up or lost most of their interstellar matter and therefore have very little ongoing star formation. They may, however, retain significant dust in their disks.

Irregular galaxy

An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy. Irregular galaxies do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearance, with neither a nuclear bulge nor any trace of spiral arm structure.

Dwarf galaxy

Despite the prominence of large elliptical and spiral galaxies, most galaxies in the Universe are dwarf galaxies. These galaxies are relatively small when compared with other galactic formations, being about one hundredth the size of the Milky Way, containing only a few billion stars. Ultra-compact dwarf galaxies have recently been discovered that are only 100 parsecs across.

Interacting

Interactions between galaxies are relatively frequent, and they can play an important role in galactic evolution. Near misses between galaxies result in warping distortions due to tidal interactions, and may cause some exchange of gas and dust. Collisions occur when two galaxies pass directly through each other and have sufficient relative momentum not to merge.

Starburst

Stars are created within galaxies from a reserve of cold gas that forms into giant molecular clouds. Some galaxies have been observed to form stars at an exceptional rate, which is known as a starburst. If they continue to do so, then they would consume their reserve of gas in a time span less than the lifespan of the galaxy. Hence starburst activity usually lasts for only about ten million years, a relatively brief period in the history of a galaxy.

Active galaxy

A portion of the observable galaxies are classified as active galaxies if the galaxy contains an active galactic nucleus (AGN). A significant portion of the total energy output from the galaxy is emitted by the active galactic nucleus, instead of the stars, dust and interstellar medium of the galaxy.

The standard model for an active galactic nucleus is based upon an accretion disc that forms around a supermassive black hole (SMBH) at the core region of the galaxy. The radiation from an active galactic nucleus results from the gravitational energy of matter as it falls toward the black hole from the disc. In about 10% of these galaxies, a diametrically opposed pair of energetic jets ejects particles from the galaxy core at velocities close to the speed of light. The mechanism for producing these jets is not well understood.

The main known types are: Seyfert galaxies, quasars, Blazars, LINERS and Radio galaxy.

source

images: NASA/ESA, Hubble (via wikipedia)

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space galaxies astronomy

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acosmicgeek

4 years ago

For a star to be born, there is one thing that must happen: a gaseous nebula must collapse. So collapse. Crumble. This is not your destruction. This is your birth.

Zoe Skylar

(via the-wolf-and-moon)

Everything that is created comes from destruction, that’d just how our universe works.

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stars astronomy destruction theuniverse

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acosmicgeek

4 years ago

Omg particles are such players - JUST CHOOSE ONE!!!

But yeah wave-particle duality is kinda confusing sometimes lol

Like, how is it both? I dunno! Maybe I’ll read up on that later ...

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Photons : Hello I’m a particle . Oh yeah but i behave like a wave too , isn’t that beautiful !!

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sciencememe wave-particle duality

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acosmicgeek

4 years ago

Galileo, what a man

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Reality is often disappointing

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acosmicgeek

4 years ago

Goddamn

We learned about the Uyuni Salt Flat in Marine Bio this year but the teacher never showed ANYTHING like this!!! I already thought that the band was beautiful, this just makes it 10 times more so. Welp, I know what to put next on my dream vacay list.

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Night Sky Reflections from the Worlds Largest Mirror : What’s being reflected in the world’s largest mirror? Stars, galaxies, and a planet. Many of these stars are confined to the grand arch that runs across the image, an arch that is the central plane of our home Milky Way Galaxy. Inside the arch is another galaxy – the neighboring Large Magellanic Cloud (LMC). Stars that are individually visible include Antares on the far left and Sirius on the far right. The planet Jupiter shines brightly just below Antares. The featured picture is composed of 15 vertical frames taken consecutively over ten minutes from the Uyuni Salt Flat in Bolivia. Uyuni Salt Flat (Salar de Uyuni) is the largest salt flat on Earth and is so large and so extraordinarily flat that, after a rain, it can become the world’s largest mirror – spanning 130 kilometers. This expansive mirror was captured in early April reflecting each of the galaxies, stars, and planet mentioned above. via NASA

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astronomy thenightsky uyunisaltflats

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acosmicgeek

4 years ago

Pass the happy! 🌌✨ When you receive this, list 5 things that make you happy and send this to 10 of the last people in your notifications!

1. Being reminded to think of happy things xD

2. Space (literally anything, you guys can tell how obsessed I am)

3. Writing Sci-Fi stories

4. Wearing a sweater on a cold day

5. Having lemon cookies to go with my coffee

Remember to all: especially in times like these, it’s nice to take a minute and think about the things that make you happy. They don’t have to be super obvious and sappy, like your family or your pet dog, they can be the little things that brighten your day. Like stars, and lemon cookies. Think about happy little things.

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acosmicgeek

4 years ago

True.

Iron actually takes more energy to fuse than it releases, so the inward pressure needed to keep the star from collapsing isn’t enough when it’s mainly fusing iron, and then it collapses.

WANT MORE? GET YOUR HEAD STUCK IN THE STARS AT MY BLOG!