1. A Possible Collaboration in Solar System Research for EAO Subaru
EAO Subaru Science Workshop 2019, KASI, 2019 January 17
A Possible Collaboration in Solar System Research for EAO Subaru
Masateru Ishiguro (Seoul National University)

2. 1. Research Objectives How did the planetary formation occur?
How was the Earth ocean created?
How did the life on Earth emerge?
We solar system researchers look for answers
in the most pristine objects in the current solar system.

3. Altwegg et al. Science 23 Jan 2015, 347, 6220

4. 2. From Hayabusa to Hayabusa2
Ordinary chondrite
We should send another spacecraft to C-type asteroid.
Image copy right: ISAS/JAXA

5. Kuroda et al. PASJ 66, 3 (2014)

6. Kuroda et al. PASJ 66, 3 (2014)
Ryugu
Moskovitz+2013

7. Ongoing Projects Asteroid Ryugu Asteroid Bennu
Image credit (JAXA for Ryugu, NASA for Bennu)
Ongoing Projects
Asteroid Ryugu
Asteroid Bennu
The sample return is an ultimate technique for investigating the original ingredients of solar system materials.
Observation research is about to shift from surfaces to interiors

8. Cometary Outbursts

9. Holmes Event Total dust mass (4–8)×1011 kg
Total kinetic energy (1–6)×1015 J
image credit John Pane via Astronomy Picture of the Day

10. Analogical Phenomena
Ishiguro, Jewitt, Hanayama et al. ApJ 787, 55 (2014)
Ishiguro, Kuroda, Hanayama, et al. AJ 152, 169 (2016)

11. * Outbursts with E>1013 J occur annually.
Holmes(*2)
Finlay(*1)
Ikeya-Murakami(*3)
Nuclear Radius(km)
2.1
1.0
<1.6
Ejection speed(m/s)
550
570±40
500±40
Ejecta mass [kg]
(6±2)×1011
≈7×108
5×108
Energy [J]
(1-6)×1015
≈1×1013
5×1012
E/M [J/kg]
1×104
10^9 kg = 60-m radius asteroid or Norikura eruption
10^13J = Little Boy (atomic bomb)
*1 Ishiguro et al. AJ 152, 169, 2016
*2 Li, J. et al. ApJ 728, 1, 31, 2011
*3 Ishiguro, M. et al. ApJ 787, 1, 55, 2014
* Outbursts with E>1013 J occur annually.

12. Asteroidal Outbursts

13. 2-1. Impact (Cratering) (596)Scheila 50° 85° 10°
Ishiguro et al. ApJ 741, 1, L24, 5 (2011)

14. 2-1. Impacts (Catastrophe)
Jewitt et al. Nature 467, 7317, 817, 2010
Kim, Y., et al. ApJL 2017, 842, 23

15. 2-2. Rotational Breakup Jewitt et al. ApJ 784, L8 (2014)

16. (596) Scheila P/2010 A2 (LINEAR) 6478 Gault
2019 January 13 (SNU Observatory)

17. Frequencies of Asteroids and Comets Outbursts
Comet Outbursts
Finlay-class: 1~2 /year
Holmes-class: 1/100 /year
Asteroid Impacts
Catastrophe： 1 /year
Cratering：　 1/10 /year
Centrifugal disintegration
Asteroids >100-m: 10 /year
* Ishiguro, Kuroda, Hanayama et al. AJ (2016)
** Jewitt, Hsieh & Agarwal, Asteroids IV221 (2015)

18. Possible Research with Subaru
Icy volatiles (Optical – NIR spectroscopy, e.g., Kawakita et al. 2014, Ootsubo et al. 2012)
Dust morphology and mineralogy (Optical – NIR polarimetry, MIR spectroscopy, Kwon et al. 2018, Watanabe et al. 2011)
Fresh internal materials, hydrated minerals (Optical – NIR spectroscopy, Usui et al. 2018)