Category Archives: Herschel Space Telescope

astrocast.tv, comet, comet dust, Herschel Space Telescope

Crystalline Entities Found in Distant Solar System

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Herschel Discovers Cometary Crystals around Beta Pictoris

We all know about comets in our own solar system. They’re conglomerates of ices mixed with dust and rock. As they get close to the Sun their gases sublimate, the dust is freed and that action creates dust and plasma tails streaming out behind the comet.  Astronomers see comets as repositories of information (in the form of those ices and dust particles) about conditions in the early solar system, since those materials have survived until this time. In particular, comets often contain materials that formed close to the Sun in the early history of the solar system, but then were somehow transported out to colder regions where comets seem to thrive.

This infrared view of the Beta Pictoris solar system, was obtained by ESO’s 3.6-meter telescope and the NACO instrument on one of the 8.2-meter units of ESO’s Very Large Telescope (inner region), and then subtracting the overpowering glare of the central star. The image shows a planet orbiting at roughly the same distance from Beta Pictoris as Saturn is from our own Sun, and a prominent dust disc in the outer reaches of the system. Credits: ESO/A-M. Lagrange et al.

So, it’s rather cool that astronomers have now found cometary particles  in another solar system, the young star Beta Pictoris. The European Space Agency’s Herschel space telescope detected pristine materials in the dust disk surrounding this star. Those materials match the makeup of comets in our own solar system.

Beta Pictoris hosts a gas giant planet, in addition to a dusty debris disk that will likely spawn the formation of some icy bodies similar to the worldlets that astronomers are finding in our own Kuiper Belt.

So, what’s the material made of that Herschel found? First, the mineral olivine is present in the disk around Beta Pic.  Olivine forms in protoplanetary disk material close to newly formed stars.  In our solar system we find it in asteroids and comets, and of course it’s found on Earth, too.

The data collected by the Herschel telescope allowed astronomers to calculate that the olivine crystals in the Beta Pic disk make up about 4% of the total mass of the dust found in a region that lies between 15 to 45 astronomical units from the star.  In our solar system, that extends from well beyond the orbit of Saturn out beyond the inner limit of the Kuiper Belt. The 4% number is quite similar to such solar system comets as 17P/Holmes and 73P Schwassmann-Wachmann 3.

Astronomers concluded that the olivine was originally bound up inside comets and released into space by collisions between the icy objects.  And, since since olivine can only crystallize  at a distance of not more than 10 astronomical units of the central star, finding it in a cold debris disc means that it must have been transported from the inner region of the system out to colder areas. A process called “radial mixing” could help push materials out away from the central star, and that could explain how the olivine crystals made it to the deep freeze of the Beta Pic system.  Want to read more about this find? Check out ESA’s Herschel Web page for the full story.

  Get Your Stargazing On for October!

This month’s edition of “Our Night Sky”, the star gazing video I produce for AstroCast.tv is now up for your viewing pleasure!  Check it out!

galactic history, galaxies, Herschel Space Telescope, starbirth

Cosmic Fireworks

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Big News in Distant Galaxies

You know that saying about how time is the universe’s way of keeping everything from happening at once? Well, there’s a lot happening in astronomy news today, almost all at once. So, the universe is flinging cool new stuff at us.

First, take a gander at this image. It’s an artist’s concept of what galaxies in the early universe were doing about 13 or so billion years ago.

 

Galaxies in the early universe grew fast by rapidly making new stars. Such prodigious star formation episodes, characterized by the intense radiation of the newborn stars, were often accompanied by fireworks in the form of energy bursts caused by the massive central black hole accretion in these galaxies. This discovery was made by a group of astronomers led by Peter Barthel of the Kapteyn Institute of the University of Groningen in the Netherlands. (Credit: ESA/NASA/RUG/MarcelZinger)

Yep, they were making stars at a prodigiously fast rate, more rapidly than many galaxies do today. By comparison, our Milky Way’s star birth factories create at an average rate of one new star a year. Ours is a pretty quiet galaxy in that regard. And, while we do have a black hole at the center of the galaxy, compared to other galaxies’ very busy black holes, ours is pretty tame. Only occasionally does it capture a star or gas cloud and gobble it up.

Now, if you look at more active galaxies, you see more  star formation. And these busy galaxies were much more common in the early universe.  So, it makes sense that astronomers would find galaxies at that time busily baking up stars. Quasars and radio galaxies are prime examples of these active galactic denizens.  And, observing them is easy due to their bright radiation, which can be detected over huge distances. Essentially, these active galaxies are easily detected through their luminous radio, ultraviolet or x-ray radiation, which results from steady accretion on to their massive central black holes.

These exotic galaxies are getting a lot of attention from the Herschel Telescope, which is sensitive to far-infrared wavelengths of light (which indicate heat radiation). A group of astronomers in the Netherlands has used it to study star birth in distant galaxies.  Basically, it looks for heat radiation generated by star and planet formation in our own galaxy, and also studies the same radiation from complete galaxies.  If a distant object is emitting strong levels of far-infrared radiation, then it’s a sure bet that the galaxy is undergoing massive amounts of star formation. And, by massive, I mean creating hundreds of stars each year.

These busy galaxies also have strong signals in radio frequencies, emanating from their central black holes. The black holes are busy growing (accreting mass and perhaps even merging), at the same time their host galaxies are creating whole batches of hot young newborn stars.  And all of it is happening billions of light-years away, showing us galaxies in some of the earliest epochs of the universe.

The take-home message here is that these kinds of active galaxies existed early in cosmic history.  They’re among the largest, most distant, most powerful and most spectacular objects in the universe. And, they give astronomers a look at what massive normal galaxies may have looked like in their infancy as they balanced the action of growing black holes at their hearts with the demands of star birth in other regions.  These are the kind of “baby pictures” of infant galaxies that give astronomers a deeper understanding of what happened “way back when” at a time when the universe was a baby.