The Asteroid/Comet Connection's
daily news journal about
asteroids, comets, and meteors

Today's issue status: done

• News briefs – comet mission & extrasolar news
• Risk monitoring

Cover: Juan Lacruz at La Canada Observatory in Spain picked up comet 32P/Comas Sola yesterday morning and this morning. He tells A/CC that, as far as he knows, this is the first this comet has been observed since June 1997. [This was confirmed for A/CC July 22nd and with the July 26th Observations of Comets MPEC–Ed.] The main image (with a satellite passing through) is a stack of 124 60-second exposures. The inset image from this morning is a stack of 150 60-second exposures. North is up and east is left. 32P was discovered in 1926 by Jose Comas Sola in Spain, and has been observed at every perihelion since.

Comet mission news:  The week of 9-16 July during the Rosetta mission first cruise phase was mostly quiet according to today's status report. (The “SSMM,” to which patch files were uploaded, is the spacecraft's Solid State Mass Memory.)

The Deep Impact mission has posted its July newsletter. Lucy McFadden has a must-read narration of the June 17th flyby sequence review. And principle investigator Mike A'Hearn reports that, after the review, there are still uncertainties about the comet nucleus reflectivity and what its orientation will be at the time of encounter, as well as about dust brightness. Recent Hubble and Spitzer space telescope observations are being analyzed to help better understand the nucleus reflectivity, shape, and rotation. He also reports that, with the successful completion of thermal-vacuum testing of the flyby/impactor stack, the impactor next has to undergo its own separate testing.

Ray Brown Ray continues his articles on Deep Impact mission science objectives with a new

educational article on comet density, porosity, and strength. There is an interview with instrument scientist Casey Lisse, who looks forward to learning “What happens when you whack a body the size of an Appalachian mountain with something the size of a small car at 6 miles per second?” And another piece tells about observing by amateur astronomer Gary Emerson, founder of Deep Impact's Small Telescope Science Program (STSP), which starts again this coming October.

Extrasolar news:  Tomorrow's edition of the journal Nature has an article about X-ray and optical observation of what's believed to be “the sudden onset of a phase of rapid accretion” in the birth of a brand new Sun-like star called V1647 Orionis, also known as IRAS 05436-0007. Vanderbilt University has a related news release today, and Space.com has a report.

This event came to the attention of professional astronomy after discovery by Kentucky amateur astronomer Jay McNeil using a 3" (78mm) telescope

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this past January and announced February 9th in IAUC 8284. He found it within the larger M78 Orion Nebula, and, now known as McNeil's Nebula, it is lit by the birthing stellar outburst, only the third ever observed and the first since the advent of X-ray astronomy. See first reports by Sky & Telescope February 17th and Space.com February 23rd. A search at S&T discovered a previous illumination from October 1966, but not in other years for which images could be found, and the magazine requested February 19th that amateurs send their older Orion Nebula M78 images, with or without McNeil's nebula showing.

That the astronomical community took quick interest in McNeil's discovery is reflected by eight other IAUCs issued during February and March: 8287, 8289, 8290, 8295, 8301, 8303, 8304, and 8306.

July 22nd update:  The Chandra X-ray Observatory has a news release today and an X-ray/optical comparison of McNeil's Nebula.

What does any of this have to do with asteroids, comets, and meteors? Planets and every class of minor object, from distant planetoids to meteors and interplanetary dust, are what remains of the Sun's own proto-planetary disk. The event in Orion discovered by Jay McNeil is believed to be the interaction of such a disk with a star, aged less than a million years, that is much like the Sun, which is about 4.6 billion years old. The Chandra news release describes the event as a violent reallignment between the star's magnetic field and the magnetic field of the circumstellar disk. This may directly relate to meteorite chemical composition. See 2002 news about how an environment bathed in X-rays may explain the oldest materials found in meteorites. And see an April item about trying to understand why particles accreted in the Sun's proto-planetary disk instead of just bouncing off each other.

Risk monitoring 21 July

The Tuesday Daily Orbit Update MPEC has observation of 2004 NL8 from Francisquito Observatory in southern California, and today both NEODyS and JPL very slightly lowered their risk assessments for this mile-size object.