Deep Sky Astronomy & Telescopes

Exploring the Galaxy’s Outer Halo

July 11, 2014

Not long ago we talked about what the Milky Way would look like when seen from afar. I had mentioned Poul Anderson’s World Without Stars, which appeared in Analog in 1966 under the title The Ancient Gods. In the Anderson tale, a starship crew is sent to make contact with a recently discovered technological civilization […]

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The Milky Way from a Distance

July 3, 2014

Growing up in the American Midwest, I used to haunt the library in Kirkwood, Missouri looking for books on astronomy. I had it in mind to read all of them and I pretty much did, looking with fascination at fuzzy images of distant objects I yearned to see close up. What did Saturn look like […]

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Intergalactic Travel via Hypervelocity Stars

June 26, 2014

We’ve been looking at not just interstellar but intergalactic crossings in the past few days, something of an homage to Carl Sagan, whose enthusiasm for continuous acceleration at 1 g and relativistic time dilation was immense in the years shortly after Robert Bussard’s key paper on interstellar ramjets. Without a working ramjet and largely unaided […]

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Gaia: Early Views, Big Prospects

February 18, 2014

We have several months yet before the European Space Agency’s Gaia mission enters its five-year operational phase. But you can see an important milestone in the image below. Gaia’s two telescopes have to be aligned and focused as its other instruments are calibrated. Testing involves downloading data like this image of NGC1818, a young star […]

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An Intergalactic River of Hydrogen?

January 28, 2014

NGC 6946, the so-called ‘Fireworks Galaxy,’ has caught the eye of many an astronomer, even if its position — close to the plane of the Milky Way and thus partially obscured by gas and dust — makes the observation difficult. At 22 million light years from Earth, this face-on spiral galaxy has been the site […]

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A Brown Dwarf Benchmark

January 21, 2014

Couple the Keck I 10-meter telescope on Mauna Kea with HIRES (the High-Resolution Echelle Spectrometer) and you get extremely high spectral resolution, making the combination a proven champion at finding planets around other stars. But it was when Justin Crepp (University of Notre Dame) and team followed up seventeen years of HIRES measurements with new […]

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Cloudy Encounter at the Core

January 13, 2014

The supermassive black hole at the center of our galaxy comes to Centauri Dreams‘ attention every now and then, most recently on Friday, when we talked about its role in creating hypervelocity stars. At least some of these stars that are moving at speeds above galactic escape velocity may have been flung outward when a […]

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Stars at Galactic Escape Velocity

January 10, 2014

How do you boost the velocity of a star up to 540 kilometers per second? Somewhere in that region, with a generous error range on either side, is the speed it would take to escape the galaxy if you left from our Solar System’s current position. Here on Centauri Dreams we often discuss exotic technologies […]

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Brown Dwarfs at the Boundary

December 10, 2013

We spend a lot of time probing the borderlines of astronomy, wondering what the boundaries are between a large gas giant and a brown dwarf, for example. The other end of that question is also intriguing: When does a true star get small enough to be a brown dwarf? For main sequence stars don’t operate […]

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Ancient Brown Dwarfs Discovered

November 21, 2013

How many brown dwarfs should we expect in the Milky Way? I can recall estimates that there could be as many brown dwarfs as main sequence stars back when people started speculating about this, but we have to go by the data, and what we have so far tells another tale. The WISE (Wide-field Infrared […]

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