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

Today's issue status: done

• News briefs – stellar influences & meteor news
• Risk monitoring
  – NEODyS has posted 2004 OT11

Cover: Comet C/2003 K4 (LINEAR) was caught by Pepe Manteca at Begues Observatory in Spain on the night of July 15th in this composite of seven 300-second exposures processed at A/CC from FITS data for tail and coma detail (north up, east left). An animation (look for “15/07/2004”) can be seen on his and Rafael Ferrando's 2003 K4 (LINEAR) page, where imagery has north down. See the Index for more images and A/CC's report about this object's September 30th passage only 20 lunar distances from Earth's orbit, but 2 AU from where we will all be at the time.

Stellar influences:  New Scientist has an article from 27 July, “Stray star may have jolted Sedna,” about a paper by Allesandro Morbidelli and Hal Levison, “Scenarios for the Origin of the Orbits of the Trans-Neptunian Objects 2000 CR105 and 2003 VB12 (Sedna),” that was submitted to the Astronomical Journal in April (576Kb PDF preprint, see March 26th “Readings”). Even without trying to follow the math, it is a very interesting read, and is best read after an accompanying paper submitted at the same time, “Sculpting the Kuiper Belt by a Stellar Encounter: Constraints from the Oort Cloud and Scattered Disk,” by Levison, Morbidelli, and Luke Dones (679Kb PDF preprint).

The latter deals with whether a star passing close to the young Sun could have resulted in the outer Solar System that is observed today:

“ An encounter strong enough to truncate the proto-planetary disk at ~50 AU requires that a fairly massive star pass within ~200 AU of the Sun [probably] while the Sun was in its birth star cluster. ”

The authors “rule out” a passage after the Sun's first ten million years with one caveat. A major constraint is that the encounter had to have happened before the Oort Cloud formed, since a star passing that close would have stripped it away, and

there is an argument that its formation may have come as late as some 700 million years into the Sun's life.

The other paper examines five scenarios for how 2000 CR105 and 2003 VB12 could have arrived at the unusual orbits they travel today. The authors settle on a low-mass stellar passage (not by the star that may have trimmed the proto-planetary disk) as most likely to have “lifted” 2000 CR105's orbit, and maybe also 2003 VB12's orbit. They note that the better explanation for 2003 VB12 may be the “exotic scenario . . . where the Sun captures a big fraction of the planetesimal disk of a small mass star” passing by. See more about 2003 VB12 via the Index, and more about 2000 CR105 in the Catchall Catalog [link|alt].

Meteor news:  Australian Broadcasting reported this morning, “Meteor lights up central Victorian sky,” saying that there were “reports of a big red and blue light streaking over the Castlemaine area just after 1:00am AEST today [that] ‘exploded into pieces.’”

The journal Science has an article today by Edwin Gnos et al. for purchase about meteorite SaU 169. Its place of origin on the Moon has been determined and a history of four major impacts, the last of which launched it into space. Today there is a University of Arizona news release and reports at Nature, Space.com, Astronomy.com, and New Scientist.

Risk monitoring 29 July

The Thursday Daily Orbit Update MPEC (DOU) has observation of 2004 OT11 from within its confirmation period yesterday morning from discoverer LINEAR in New Mexico and Robert Hutsebaut in Belgium operating a telescope in New Mexico (see the A/CC cover image yesterday). And the DOU has observations on both sides of last midnight from Wildberg Observatory in Germany. Today NEODyS posted this object, while JPL raised its risk ratings and diameter estimate (to 1.3 km. = 0.8 mile) and increased its impact solution count.

Both risk monitors are showing their earliest solutions as four years from last week. Based on observations spanning less than 39 hours, these risk assessments are of course highly preliminary and will change as the night-and-day cycle of observation and analysis progresses. (If you are new to impact hazard monitoring, please read “Understanding Risk Pages” by Jon Giorgini of JPL.)

The DOU also has observation of 2004 NL8 from Naef Observatory in Switzerland late Tuesday night, and yesterday morning from Powell Observatory in Kansas. Today NEODyS posted a new impact solution for this kilometer-size object with a slightly raised risk rating.