Sunday Night Stargazin’

Have a Conjunction with the Night Sky

According to the folks over at Spaceweather.com (who ping me daily with cool and useful information), there’s going to be a neat conjunction in the western sky tonight (for those of you readers who haven’t experienced sunset yet).  The crescent Moon, Mercury, and the Pleiades star cluster will be grouped together after sunset.  So, go out after sunset, look west, and watch the western sky in the gathering gloom!  Read more about this at the link above.

As much as I like spring and summer, I’m always a little triste to see the Pleiades disappear from our evening and early morning skies for a few months. They’ll reappear in the night sky in the mid-autumn (for Northern Hemisphere gazers, mid-spring for the folks south of the equator), and they’ll be a harbinger of brighter, glitterier things to come (like Orion, yah!!!).   So, I’ll check it out tonight, provided it’s not cloudy.

Diamonds Loose in the Sky

All that Glitters

When you look at the night sky, of course you see stars glittering up there. And, planets.  And, if you  have a telescope, you can make out the blurry wisps of nebulae and galaxies.  Nebulae are clouds of gas and dust that float in space. They can be starbirth regions, the outpouring of a star (or stars) dying, and a mixture of both.

As it turns out, when you look at the clouds of gas and dust (called circumstellar disks) surrounding some special types of stars, you are looking at something else that glitters: diamonds.  In these regions, there are countless numbers of these tiny sparklers (and I do mean tiny — most are not even the width of a human hair) swarming around in those disks. Yet around some stars, there are enough diamond specks that if you packed them all together, they’d have enough mass to make a tiny moonlet.

Artist's conception of where diamonds are found in circumstellar disks with special conditions that lead to the formation of such diamonds. Courtesy Subaru Telescope, NAOJ. (Click to embiggen.)

How can diamonds form in space? It’s a detective story, really, and a group of scientists from Japan, Germany, and Denmark used Subaru telescope on Mauna Kea in Hawai’i, to study ayoung star called Elias 1 to solve the central riddle of that story: how can diamonds form in space?

When scientists look for diamonds in space, they are like detectives using fingerprints to trace a missing person or find the perpetrator of a crime. The fingerprints of diamond crystals take the form of  lines in the infrared wavelength of light, outside the range of visible light. The first such signature was discovered in 1983 in the circumstellar disk of Elias 1, a young star located in the direction of Taurus. It is is one of many Herbig Ae/Be (HAEBE) stars?young, very bright stars that are about 1.5-10 times as massive as our Sun.

The research team began with clues from previous laboratory research into how diamonds are formed (carbon materials are subjected to  great temperatures and pressures).  They coupled this with observations of stars that are surrounded by dust, and have partner stars that emit tremendous bursts of hard x-ray emissions.   X-rays are emitted under extremely energetic and hot conditions, so that supplies the necessary energy and pressure for a natural diamond factory in space.

The scientists knew from their research that diamonds are formed close to the stars where they exist. They aren’t floating in from random points in space.  Also, diamond stars must have special ingredients: that disk full of carbon material, a hot central star and a companion emitting hard x-rays. The star must be of intermediate mass that can warm up the disk to a medium temperature. Then, carbon onions can form, providing the cradle for diamond creation. The need for such special conditions would explain why we see so few stars with diamond signatures in their disks.

The findings of this research (more details here) will raise even more questions and speculation about the formation of these fascinating crystals. It’s possible that there are tons of diamonds that astronomers cannot yet see because their emissions are hidden from view by shells of material surrounding the stars where they exist.

A Black Hole Gets the Vapors

There’s Water Out There — WAY Out There!

You know that stuff that falls out of the sky, runs through rivers, fills the oceans, makes up ice cubes here in our refrigerators on Earth? That water stuff?  Well, it can be found in some pretty distant reaches of the cosmos, not just here on good ol’ planet Earth (or locked away on a Martian polar ice cap or under Europa’s shimmering icy surface). Astronomers have found signs of water in a very distant part of universe. It’s actually water vapor contained in a jet ejected from a supermassive black hole that lies billions of light-years away from us.  That water vapor existed near the black hole at a point about 2.5 billion years AFTER the Big Bang. That is an incredibly long time ago, and shows us the scene at a time when the universe was still quite young.

The black hole is jackhammering out of a galaxy called MG J0414+0534, and what the astronomers saw was the telltale fingerprint of water vapor in emissions from something called a maser. This is a region of gas where molecules in the gas amplify and emit beams of microwave radiation in much the same way as a laser emits beams of light. For it to show the fingerprint of water vapor scientists detected means that the gas-emitting region is hot and dense enough to heat water to its boiling point.

This image is made from HST data and shows the four lensed images of a dusty red quasar (which contains the jet and water maser emissions), connected by a gravitational arc of the quasar host galaxy. The lensing galaxy is seen in the center, between the four lensed images. (Courtesy John McKean/HST Archive data. Click to embiggen.)

This water maser emission is not something you can see with an optical telescope. You need radio telescopes like the Extended Very Large Array and the Effelsberg radio telescope that can detect the emissions, and you need a gravitational lens. The gravitational lens acts as if it was a telescope, bending and magnifying light from the distant galaxy to make a clover-leaf pattern of four images of MG J0414+0534.