Sunday, April 11, 2010

Disk occulting Epsilon Aurigae resolved with optical interferometry

When the approaching rare eclipse of Eps Aur was advertised in earnest in 2008 it was mentioned (3rd graf) that optical interferometers would try to watch 'close-up' what was happening in that mysterious system. This week we learned that the technique has succeeded! A sequence of interferometric images with the Michigan Infra-Red Combiner (MIRC) instrument at the CHARA array on Mt. Wilson near LA in CA is good enough to show a dark disk move over the bright star: The images zoom in enough to reveal the shape of the dark object's shadow. A geometrically thin, dark, dense, but partially translucent cloud can be seen passing in front of Epsilon Aurigae, demonstrating that the basic paradigm for the eclipses was right, although the disk appears much flatter than recent modeling from the Spitzer Space Telescope suggests. A lot of coverage here, here, here, here, here, here, here, here, here, hier und hier, further discussion here, here and here and the light curve.

The Venus/Mercury pair "dominated" the other news in the past week, with the latter fading rapidly in the last few days: selected images of today from Germany, yesterday from Canada and Germany (more), April 9 from the U.S. (more) and Germany, April 8 from Austria and Germany (wide view with Mars included!), April 7 from the U.K. (more, more) and Germany, April 6 from Austria and Germany (with the Pleiades and some effects; more, more, more, more and more, also the 2 preceding ones), April 5 from the U.S., U.K., Spain and Germany (more, more and more, also the 4 preceding ones), April 4 from the U.S. (more) and the U.K., April 3 from the U.S. and U.K., April 2 from Austria and Germany (more and more) and April 1 from Germany (timelapse video). One of mine also made it into this collection and Venus and Mercury were resolved in daytime observations - plus the future of Venus this year. • Mars is now in the Beehive; images of April 10 (also a drawing), April 6 and April 2 and Saturn on April 8 (more and more, incl. an animation).

In yet other news another sungrazing comet came and vanished (animation, story, still), images of 81P/Wild of April 10, April 9, April 8 (more), April 5 and April 4, with a substantial dust tail, split C/2007 Q3 (Siding Spring) today (processed), on April 9 (more, processed), April 5 and April 2, also Machholz and a new Boattini. • A proposal regarding a lower size limit for dwarf planets made headlines here and here, Quaoar is very dense, a minor planet came close, a meteorite hit a car in Canada, others were found after the Feb. 28 bolide, a visit to the Hoba meteorite and a JPL Release advertising meteor showers.

• From the Jan. 15 annular eclipse in India a new Baily's Beads movie from the edge and a slide show from Kanyakumari. • The profile of asteroid Anastasia from an occultation of a bright star (most missed it), and a video of a short grazing occultation by the Moon. • A faint aurora was seen over N. Germany (more; story), plus spot 1057. • A video and a picture (report) of the ISS crossing the Sun and a picture of the ISS over the Moon (more). • The aurora from the ISS (later). • And phenomenal cloud FX after the last STS launch, discussed hier, here, here, here, here, here, here and here.

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