Pluto at center with its large moon, Charon, and small moons Hydra and Nix, from the Hubble Space Telescope in 2005. Charon has been in the news recently about its water-ice surface and possible cryovolcanism, and see news below about Hydra and Nix. Credit: NASA, ESA, H. Weaver, A. Stern, and the HST Pluto Companion Search Team.
Contents on 20 July '07
- Minor-Object News -- five items
- Minor-Object Science -- five papers
- IAU Minor Planet Center
- Impact Risk Monitoring -- nothing to report
- Consolidated Risk Tables - CRT page
- Ephemerides for risk-rated objects
- Ephemerides for small asteroids
Navigation tips: Use the << and >> arrows on the menus for each regular section (Observers, Risks, etc.) to move to the previous and next day's news for that section. Use the Index menu item to access specific days this year through a calendar interface. And use the all-up news archive to access news from any time since A/CC began in early 2002. To keep track of what's new each day, watch the Chronology section.
Minor-Object News on 20 July '07
- "Researchers scour Prairies for meteorites," SNN at Star Phoenix 20 July - Quote: "Geology detectives in Saskatchewan might have made two important discoveries this summer. And, as it usually happens for members of the multi-university partnership Prairie Meteorite Search, the finds have come from unexpected places."
- Na Kilo Hoku: The University of Hawaii Institute for Astronomy has posted the 23rd edition (second for 2007) of its newsletter. In one article, "Pluto's Family," David Tholen reports that observations of the Pluto system find that the smaller moons Hydra and Nix "are nearly coplanar with Charon's orbit, which strongly suggests a common formation mechanism for all three satellites" (see an HST image of the Pluto system above). Another article explains briefly how "Antarctic Meteorites Reveal Solar System History." Light pollution is becoming a problem on the islands with big telescopes and "New Lighting Law Protects Observatories" tells about steps taken to fix that.
- "Ball of Gas Meets Ball of Stars," Sky & Telescope 20 July - Quote: "On Sunday evening, Comet LINEAR (C/2006 VZ13) passes within kissing distance of the great globular star cluster Messier 3... This is a great chance to see exactly why Charles Messier decided to include this cluster in his catalog of comet-impostors."
- "Hanging out with black hole physicists," Nunatsiaq News 20 July - Quote: "The scientists are here because they believe the Haughton impact crater ... closely resembles the landscape of Mars. [Jarloo] Kiguktak is here, with a rifle slung over his shoulder, so none of the scientists are eaten by polar bears."
- "Aucklanders treated to meteorite display," TV3 News 20 July - Quote: "Early risers in Auckland were treated to a natural fireworks display this morning -- spotting a meteorite flashing across the West Coast sky." - Note: On-air audio of witness reports is available.
Minor-Object Science on 20 July '07
- "Debris Disks in NGC 2547" by Gorlova, N. with Z. Balog, G.H. Rieke & 4 others, abstract & PDF at arXiv.org 20 July - Quote: "We have surveyed the 30 Myr-old cluster NGC 2547 for planetary debris disks using Spitzer. At 4.5-8 um we are sensitive to the photospheric level down to mid-M stars (0.2 Msol) and at 24 um to early-G stars (1.2 Msol). We find only two to four stars with excesses at 8 um out of ~400-500 cluster members, resulting in an excess fraction <~1 percent at this wavelength. By contrast, the excess fraction at 24 um is ~40 percent (for B-F types). Out of four late-type stars with excesses at 8 um two marginal ones are consistent with asteroid-like debris disks. Among stars with strong 8 um excesses one is possibly from a transitional disk, while another one can be a result of a catastrophic collision. Our survey demonstrates that the inner 0.1-1 AU parts of disks around solar-type stars clear out very thoroughly by 30 Myrs of age."
- "Coronal abundances of X-ray bright pre-main sequence stars in the Taurus Molecular Cloud" by Scelsi, L. with A. Maggio, G. Micela & 2 others, abstract & PDF at arXiv.org 20 July - Quote: "We studied the thermal properties and chemical composition of the X-ray emitting plasma of a sample of bright members of the Taurus Molecular Cloud to investigate possible differences among classical and weak-lined T Tauri stars and possible dependences of the abundances on the stellar activity level and/or on the presence of accretion/circumstellar material."
- "Formation of Protoplanets from Massive Planetesimals in Binary Systems" by Tsukamoto, Yusuke with Junichiro Makino, abstract & PDF at arXiv.org 20 July - Quote: "More than half of stars reside in binary or multiple star systems and many planets have been found in binary systems. From theoretical point of view, however, whether or not the planetary formation proceeds in a binary system is a very complex problem... We performed N-body simulations of planetary formation in binary systems starting from massive planetesimals whose size is about 100-500 km. [and found that the] basic processes of the planetary formation ... are essentially the same in binary systems and single star systems, at least in the late stage where the effect of gas drag is small."
- "Molecular line radiative transfer in protoplanetary disks: Monte Carlo simulations versus approximate methods" by Pavlyuchenkov, Ya. with D. Semenov, Th. Henning & 4 others, abstract & PDF at arXiv.org 20 July - Quote: "We analyze the line radiative transfer in protoplanetary disks using several approximate methods and a well-tested Accelerated Monte Carlo code."
- "The 105 Lsun High-Mass Protostellar Object IRAS 23151+5912" by Beuther, H. with Q. Zhang, T.R. Hunter & 2 others, abstract & PDF at arXiv.org 20 July - Quote: "With a size of approximately 5000 AU and no Keplerian rotation signature, this structure does not resemble a genuine accretion disk but rather a larger-scale rotating toroid that may harbor a more common accretion disk at its so far unresolved center."
NEOCP Activity on 20 July '07
The MPC's NEO Confirmation Page has 7 listings: 2 new, 5 updated
When last checked at 2355 UTC today, the Minor Planet Center's NEO discovery Confirmation Page (NEOCP) had two new and five updated listings. Of these, three were "one nighters."
New MPECs on 20 July '07
Minor Planet Electronic Circulars
There was one MPEC issued this day from the International Astronomical Union's Minor Planet Center in Cambridge, Massachusetts.
- Observations of small asteroids (H>22.0)
- K07N04T 2007 NT4 (arc=4 days, H=23.8 ~59m) from Mt. John Obs. (July 19.53-54p4)
- Observations of other objects
- K07N05C 2007 NC5 (q=0.283 AU, Q=4.405 AU, arc=15 days, H=18.0 ~851m) from Irmtraut Obs. (July 19.04p1)
- K07M24B 2007 MB24 (i=47.7°, arc=25 days, H=18.4 ~708m) from New Millennium Obs. (July 18.96-00p9)
- K07L32R 2007 LR32 (arc=55 days, H=17.3 ~1.17 km) from New Millennium Obs. (July 18.99-07p12) and Petit Jean Mtn. South Obs. (PJMSO) (July 19.36-37p7)
- K07L15A 2007 LA15 (arc=36 days, H=19.5 ~426m) from PJMSO (July 19.25p6)
- K07L08V 2007 LV8 (arc=37 days, H=20.2 ~309m) from PJMSO (July 19.28-29p6)
- K07L00F 2007 LF (arc=42 days, H=20.5 ~269m) from PJMSO (July 19.27-28p6)
- K07C26K 2007 CK26 (arc=2 opp, H=19.1 ~513m) from PJMSO (July 19.33p6)
- K06X00A 2006 XA (arc=230 days, H=17.3 ~1.17 km) from PJMSO (July 19.35-36p4)
- K05G22O 2005 GO22 (q=0.336 AU, arc=2 opp, H=18.7 ~616m) from LINEAR (July 19.31-33p3)
- K04S09T 2004 ST9 (arc=2 opp, H=18.0 ~851m) from New Millennium Obs. (July 18.96-00p5) and PJMSO (July 19.32p5)
- K03M09T 2003 MT9 (q=0.200 AU, Q=4.874 AU, arc=2 opp, H=18.6 ~645m) from LINEAR (July 19.30-32p3)
- K03H02F 2003 HF2 (q=0.361 AU, arc=4 opp, H=19.6 ~407m) from Mandi Obs. (July 17.92-95p3) and PJMSO (July 19.22-23p5)
- J99V06O 1999 VO6 (i=40.1°, q=0.297 AU, arc=8 opp, H=17.0 ~1.35 km) from PJMSO (July 19.34-35p5)
- J97P00N 1997 PN (arc=2 opp, H=19.8 ~371m) from LINEAR (July 19.34-38p5)
- F4269 154269 2002 SM from the Siding Spring Survey (SSS) (July 19.73-75p4)
- F3415 153415 2001 QP153 from LINEAR (July 19.39-43p4)
- E5656 145656 4788 P-L from PJMSO (July 19.23-24p5)
- E0158 140158 2001 SX169 from LINEAR (July 19.31-33p3)
- D6818 136818 1997 MW1 from New Millennium Obs. (July 18.90-95p6)
- 85275 85275 1994 LY from New Millennium Obs. (July 18.91-99p11) and PJMSO (July 19.30-31p5)
- 24443 24443 2000 OG from LINEAR (July 19.24-27p4)
- 18882 18882 1999 YN4 from LINEAR (July 19.23-27p5)
- 02100 2100 Ra-Shalom (1978 RA) from the Mt. Lemmon Survey (MLS) (July 19.44-45p4) and the Catalina Sky Survey (CSS) (July 19.45-47p4)
- 00433 433 Eros (1898 DQ) from LINEAR (July 19.23-27p5)
Observers on 20 July '07
Nine observing facilities appeared in this day's MPECs.
|703||Catalina Sky Survey in Arizona, 1 in MPEC 2007-O33 -- 2100|
|A21||Irmtraut Obs. in Germany, 1 in MPEC 2007-O33 -- 2007 NC5|
|704||LINEAR in New Mexico, 8 in MPEC 2007-O33 -- 2005 GO22, 2003 MT9, 1997 PN, 153415, 140158, 24443, 18882, 433|
|B28||Mandi Obs. in Italy, 1 in MPEC 2007-O33 -- 2003 HF2|
|474||Mt. John Obs. in New Zealand, 1 in MPEC 2007-O33 -- 2007 NT4|
|G96||Mt. Lemmon Survey in Arizona, 1 in MPEC 2007-O33 -- 2100|
|A24||New Millennium Obs. in Italy, 5 in MPEC 2007-O33 -- 2007 MB24, 2007 LR32, 2004 ST9, 136818, 85275|
|H45||Petit Jean Mtn. South Obs. in Arkansas, 11 in MPEC 2007-O33 -- 2007 LR32, 2007 LA15, 2007 LV8, 2007 LF, 2007 CK26, 2006 XA, 2004 ST9, 2003 HF2, 1999 VO6, 145656, 85275|
|E12||Siding Spring Survey in New South Wales, 1 in MPEC 2007-O33 -- 154269|
Chronology on 20 July '07
Times are UTC for when the items were noted or added by Major News.
|1516||Added news report, "Na Kilo Hoku"|
Added link to news story, "Researchers scour Prairies for meteorites"
Added link to news story, "Hanging out with black hole physicists"
Added link to news story, "Ball of Gas Meets Ball of Stars"
|1336||Grabbed MPEC 2007-O33 - Daily Orbit Update - see above|
|0418||Added MOS paper, "Coronal abundances of X-ray bright pre-main sequence stars in the Taurus Molecular Cloud" - see above|
Added MOS paper, "Debris Disks in NGC 2547" - see above
Added MOS paper, "Formation of Protoplanets from Massive Planetesimals in Binary Systems" - see above
Added MOS paper, "Molecular line radiative transfer in protoplanetary disks: Monte Carlo simulations versus approximate methods" - see above
Added MOS paper, "The 105 Lsun High-Mass Protostellar Object IRAS 23151+5912" - see above
Added link to news story, "Aucklanders treated to meteorite display"