Atop the gantry at Pad 17-B at Cape Canaveral Air Force Station on Saturday, the Dawn spacecraft was removed from its Delta II launcher second stage to be stored until a new launch window opens during September and October. Credit: NASA KSC.
Contents on 24 July '07
- Minor-Object News
- 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 24 July '07
There is no news to report yet today (none found or none prepared).
Minor-Object Science on 24 July '07
- "Collisional Velocities and Rates in Resonant Planetesimal Belts" by Queck, Martina with Alexander V. Krivov, Miodrag Sremcevic & Philippe Thebault, abstract & PDF at arXiv.org 24 July - Quote: "We consider a belt of small bodies around a star, captured in one of the external or 1:1 mean-motion resonances with a massive perturber. The objects in the belt collide with each other. Combining methods of celestial mechanics and statistical physics, we calculate mean collisional velocities and collisional rates, averaged over the belt. The results are compared to collisional velocities and rates in a similar, but non-resonant belt, as predicted by the particle-in-a-box method. It is found that the effect of the resonant lock on the velocities is rather small, while on the rates more substantial. The collisional rates between objects in an external resonance are by about a factor of two higher than those in a similar belt of objects not locked in a resonance. For Trojans under the same conditions, the collisional rates may be enhanced by up to an order of magnitude. Our results imply, in particular, shorter collisional lifetimes of resonant Kuiper belt objects in the solar system and higher efficiency of dust production by resonant planetesimals in debris disks around other stars."
- "The Hot Inner Disk of FU Ori" by Zhu, Zhaohuan with Lee Hartmann, Nuria Calvet & 3 others, abstract & PDF at arXiv.org 24 July - Quote: "We have constructed a detailed radiative transfer disk model which reproduces the main features of the spectrum of the outbursting young stellar object FU Orionis from ~4000 angstrom, to ~8 micron. Using an estimated visual extinction Av~1.5, a steady disk model with a central star mass ~0.3 Msun and a mass accretion rate ~2e-4 Msun/yr, we can reproduce the spectral energy distribution of FU Ori quite well. With the mid-infrared spectrum obtained by the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope, we estimate that the outer radius of the hot, rapidly accreting inner disk is ~1 AU using disk models truncated at this outer radius. Inclusion of radiation from a cooler irradiated outer disk might reduce the outer limit of the hot inner disk to ~0.5 AU. In either case, the radius is inconsistent with a pure thermal instability model for the outburst. Our radiative transfer model [suggests] that the magnetorotational instability (MRI) can be supported out to that distance."
- "12 and 18 micron images of dust surrounding HD 32297" by Moerchen, Margaret M. with Charles M. Telesco, James M. De Buizer & 2 others, abstract & PDF at arXiv.org 24 July - Quote: "We present the first subarcsecond-resolution images at multiple mid-IR wavelengths of the thermally-emitting dust around the A0 star HD 32297. Our observations ... reveal a nearly edge-on resolved disk ... that extends ~150 AU in radius... The global mid-IR colors and detailed consideration of the radial color-temperature distribution imply that the central part of the disk out to ~80 AU is relatively deficient in dust."
- "A Ring of Warm Dust in the HD 32297 Debris Disk" by Fitzgerald, Michael P. with Paul G. Kalas & James R. Graham, abstract & PDF at arXiv.org 24 July - Quote: "We report the detection of a ring of warm dust in the edge-on disk surrounding HD 32297... An analysis of the stellar component of the SED suggests a spectral type later than A0... The inner boundary of the warm dust is located [~65 AU] from the star... Previous indirect estimates of the stellar age (~30 Myr) indicate the dust is composed of debris. The peak vertical optical depths in our models ... imply that grain-grain collisions likely play a significant role in dust dynamics and evolution. Submicron grains can survive radiation pressure blow-out if they are icy and porous. Similarly, the inferred warm temperatures (130-200 K) suggest that ice sublimation may play a role in truncating the inner disk."
- "The Circumstellar Structure and Excitation Effects around the Massive Protostar Cepheus A HW 2" by Torrelles, J.M. wutg N.A. Patel, S. Curiel & 3 others, abstract & PDF at arXiv.org 24 July - Quote: "We report SMA 335 GHz continuum observations ... together with VLA ammonia observations ... toward Cep A HW 2. We find ... an elongated structure of [450 AU] peaking on HW 2. In addition, two ammonia cores are observed ... and an elongated core... All these results argue against the interpretation of the elongated dust-gas structure as due to a chance-superposition of different cores; instead, they imply that it is physically related to the central massive object within a disk-protostar-jet system."
NEOCP Activity on 24 July '07
The MPC's NEO Confirmation Page has 2 listings: 2 updated
When last checked at 2357 UTC today, the Minor Planet Center's NEO discovery Confirmation Page (NEOCP) had two updated listings.
To learn how observers use the NEOCP, see Suno Observatory's Practical guide on how to observe NEOCP object.
New MPECs on 24 July '07
Minor Planet Electronic Circulars
As of last check at 2357 UTC, there has been one MPEC issued today from the International Astronomical Union's Minor Planet Center in Cambridge, Massachusetts.
- Observations of small asteroids (H>22.0)
- K07H15D 2007 HD15 (arc=27 days, H=24.0 ~54m) from Modra Obs. (April 24.02-03p3)
- K07E26N 2007 EN26 (arc=17 days, H=22.5 ~107m) from Schiaparelli Obs. (March 13.08-09p3)
- Observations of almost-small asteroids (21.7<H<=22.0)
- K07K02W 2007 KW2 (arc=51 days, H=22.0 ~135m) from Astronomical Research Obs. (ARO) (July 23.17p2)
- Observations of other objects
- K07M20T 2007 MT20 (arc=23 days, H=18.7 ~616m) from Schiaparelli Obs. (July 4.89-91p3)
- K07M13M 2007 MM13 (i=38.2°, arc=30 days, H=17.6 ~1.02 km) from ARO (July 23.16p3)
- K07L19V 2007 LV19 (arc=38 days, H=19.9 ~355m) from ARO (July 23.13-14p3)
- K07L08V 2007 LV8 (arc=37 days, H=20.2 ~309m) from Schiaparelli Obs. (June 16.89-90p2)
- K07H70D 2007 HD70 (arc=89 days, H=21.0 ~214m) from ARO (July 23.23p1)
- K07G05Z 2007 GZ5 (arc=92 days, H=21.2 ~195m) from Modra Obs. (April 15.96-97p2)
- K07E00X 2007 EX (arc=135 days, H=17.0 ~1.35 km) from Tiki Obs. (July 23.20-23p2)
- K07DA3T 2007 DT103 (arc=147 days, H=18.6 ~645m) from Simeis Astrophysical Obs. (July 22.79-80p14)
- K03M09T 2003 MT9 (q=0.200 AU, Q=4.874 AU, arc=2 opp, H=18.6 ~645m) from Hamamatsu-Yuto Obs. (July 22.60p1 & 22.66p1)
- K03B43B 2003 BB43 (i=40.9°, arc=3 opp, H=17.1 ~1.29 km) from ARO (July 23.29-31p3)
- K01M18T 2001 MT18 (arc=5 opp, H=18.2 ~776m) from ARO (July 23.35-37p3)
- K01F01A 2001 FA1 (arc=4 opp, H=17.7 ~977m) from ARO (July 23.25-28p3)
- E5656 145656 4788 P-L from Hamamatsu-Yuto Obs. (July 23.48p5)
- 85275 85275 1994 LY from Hamamatsu-Yuto Obs. (July 23.50p5)
Observers on 24 July '07
Six observing facilities appear in today's MPECs.
|H55||Astronomical Research Obs. in Illinois, 7 in MPEC 2007-O41 -- 2007 KW2, 2007 MM13, 2007 LV19, 2007 HD70, 2003 BB43, 2001 MT18, 2001 FA1|
|379||Hamamatsu-Yuto Obs. in Japan, 3 in MPEC 2007-O41 -- 2003 MT9, 145656, 85275|
|118||Modra Obs. in Slovakia, 2 in MPEC 2007-O41 -- 2007 HD15, 2007 GZ5|
|204||Schiaparelli Obs. in Italy, 3 in MPEC 2007-O41 -- 2007 EN26, 2007 MT20, 2007 LV8|
|094||Simeis Astrophysical Obs. in Ukraine, 1 in MPEC 2007-O41 -- 2007 DT103|
|F85||Tiki Obs. in Tahiti, 1 in MPEC 2007-O41 -- 2007 EX|
Impact Risk Monitoring on 24 July '07
At last check (NEODyS and JPL at 2357 UTC) there was no risk monitoring news to report yet today.
Chronology on 24 July '07
Times are UTC for when the items were noted or added by Major News.
|1422||Added MOS paper, "12 and 18 micron images of dust surrounding HD 32297" - see above|
Added MOS paper, "A Ring of Warm Dust in the HD 32297 Debris Disk" - see above
Added MOS paper, "Collisional Velocities and Rates in Resonant Planetesimal Belts" - see above
Added MOS paper, "The Circumstellar Structure and Excitation Effects around the Massive Protostar Cepheus A HW 2" - see above
Added MOS paper, "The Hot Inner Disk of FU Ori" - see above
|1411||Grabbed MPEC 2007-O41 - Daily Orbit Update - see above|