1. Physics of two PHAs using groundbased observations
M. Birlan1,2, M. Popescu2,1, A. Nedelcu2,1,
A. Sonka2, B. Dumitru1,3
IMCCE, CNRS UMR8028, Observatoire de Paris
Astronomical Institute, Romanian Academy
Institute for Space Science, Romania
AIM, Madrid, March 1-2, 2016

2. Asteroid population More than 700,000 objects
13,500 Near-Earth Asteroids (NEA),
~900 Potential Hazardous Asteroids (PHA)
~11% of NEA
Population with known spectral trends
(1,400 objects)
2007 PA8
2004 BL86
AIM, Madrid, March 1-2, 2016

3. Discover an asteroid- short opportunities for NEA
AIM, Madrid, March 1-2, 2016
Credits:

4. Spectroscopy - NEAs Geometries of observations - only few / century
Spectroscopy – one spectrum for the major part of observed NEAs
New constrains concerning their phisics
Requires medium to large groundbased facilities & dedicated observing instruments/modes
AIM, Madrid, March 1-2, 2016

5. 2007 PA8 Tisserand parameter – 2.947 (close to JFC)
Belongs to the 5% largest PHA
Delta V = 6.8 km/s
MOID = 0.024
Close approach 5 Nov 2012
Diameter: ~ 2km
AIM, Madrid, March 1-2, 2016

6. 2007 PA8 IRTF – September 2012 Band I & II parameters
2007 PA8 more akin to H chondrites
Fresh surface
No taxonomic match in Bus-DeMeo taxonomy
AIM, Madrid, March 1-2, 2016

7. 2007 PA9 - dynamics Backward integration of 1,275 clones for 200kyrs
Evolution of population & density of population/century in (a,e) space
Nedelcu et al, A&A, 2014
AIM, Madrid, March 1-2, 2016

8. 2007 PA8 - Remarks
Piece of a larger H –like parrent body in the Main Belt
Parrent body other than asteroid 6 Hebe
Express delivery from the Main-Belt to NEAs
AIM, Madrid, March 1-2, 2016

9. 2004 BL86 - Grazed the Earth : Jan 26, 2015
- Distance: 1.2 million km.
- Discovered in 2004 (LINEAR program)
Estimated diameter: 500m
Arecibo radar : binary object
AIM, Madrid, March 1-2, 2016

10. Physical properties
Usually observations using 3m diameter facilities: IRTF (Hawaii) & INT (Canarias Islands) operated remotely from Paris Observatory (CODAM) or Bucharest-Astronomical Institute (ROC).
CODAM
ROC
AIM, Madrid, March 1-2, 2016

11. 2004 BL86
Successful observing runs in Feb 6 & 7, 2015, first spectrum of this PHA (INT/Vis + IRTF/Nir)
AIM, Madrid, March 1-2, 2016

12. 2004 BL86 Analysis - BL86 is V-type asteroid
Mineralogical analysis: 2004 BL86 has a basaltic mineralogy
Thermal albedo of BL86 help in deriving a diameter of 290 ± 20 m.
AIM, Madrid, March 1-2, 2016

13. 2004 BL86
Spectroscopic analysis diminish by 40% the diameter previously estimated
Long term orbital integrations using clones show that 2004 BL86 is highly chaotic
No keyhole for hitting the Earth in the next five centuries
Next favorable observation of 2004 BL86 in 2050!
Birlan et al A&A, 2015
AIM, Madrid, March 1-2, 2016

14. AIM, Madrid, March 1-2, 2016

15. NIR spectroscopy – 809 Lundia
Hunting for the right time
needs – physical ephemerides
Coordinate photometry & spectroscopy
AIM, Madrid, March 1-2, 2016