1. The Dust Environment of Main-Belt Comet P/2012 T1 (Pan-STARRS) Moreno, F.(1); Cabrera-Lavers, A.(2,3,4); Vaduvescu, O.(2,5); Licandro, J.(2,3); Pozuelos, F.(1) (1): Instituto de Astrofísica de Andalucía, CSIC, Granada (2): Instituto de Astrofísica de Canarias (3): Universidad de La Laguna, Tenerife (4): Gran Telescopio Canarias (GTC Project) (5): Isaac Newton Group of Telescopes, La Palma EPSC London, September 10th, 2013

2. MBCs: New comet reservoir ? Most are dynamically stable ≈100 Myr Recurrent activity Earth’s water contribution P/2013 P5 New !!

3. Characterize a new Solar System family, the MBCs, by in situ investigation Understand the physics of activity on MBCs Directly detect water in the asteroid belt Test whether MBCs are a viable source for Earth´s water Use MBCs as tracers of planetary system formation and evolution CASTALIA: A MISSION TO A MAIN-BELT COMET A mission proposal is being prepared to be submitted to the next ESA’s M4 call: See poster by Boehnhardt et al.

4. OBSERVATIONS OF P/2012 T1 (PANSTARRS) Roque de los Muchachos Observatory, La Palma DATE (UT)DAYS AFTER PER. Tp=2012/09/10.9 INSTRUM./TELESC.RESOLUTIONm(1,1,0) 2012 Nov 13.163.2PFIP/WHT 4.2m265.8 km/px16.9±0.2 2012 Nov 20.070.1OSIRIS/GTC 10.4m274.8 km/px17.0±0.2 2012 Dec 13.994.0OSIRIS/GTC 10.4m307.1 km/px17.3±0.2 2013 Jan 17.9129.0OSIRIS/GTC 10.4m385.4 km/px17.7±0.2 2013 Feb 17.9160.0OSIRIS/GTC 10.4m466.4 km/px18.9±0.2 2013 Feb 27.9170.0LIRIS/WHT 4.2m485.0 km/pxK S ≥22.8±0.1 2013 Feb 27.9170.0ACAM/WHT 4.2m485.0 km/px-- Seeing conditions: 0.9”-1.1” GTC WHT

5. P/2012 T1 (PANSTARRS) OSIRIS@GTC PFIP@WHT Red bandpasses Moreno et al. ApJL 2013 in press Nov 13, 2012 Nov 20, 2012 Feb 18, 2013 Dec 14, 2012Jan 18, 2013 Moreno et al. 2013

6. MONTE CARLO DUST TAIL/COMA MODEL (Moreno et al.) DYNAMICAL/RADIATIVE CODE - COMPUTE POSITION IN THE SKY PLANE OF PARTICLES EJECTED FROM NUCLEUS - CALCULATE TAIL BRIGHTNESS FROM LIGHT SCATTERING PROPERTIES OF DUST GRAINS MODEL PARAMETERS: 1)EJECTION VELOCITY OF GRAINS AS FUNCTIONS OF SIZE: V(1-µ,t)=v 1 (t)(1-µ) 1/k, k≥2 2)SIZE DISTRIBUTION: n(r)=Cr -α, GRAINS DISTRIBUTED IN SIZES FROM µm TO cm 3)MASS LOSS RATE 4)EJECTION PATTERN COMPARE SYNTHETIC TAIL WITH OBSERVATIONS AND COMPUTE STANDARD DEVIATION

8. Observation Model

9. P/2012 T1 (PANSTARRS) ISOTROPIC MODEL Moreno et al. 2013 Nov.13 Nov.20 Dec.14 Jan.18 m R (Observed)m R (Model) Oct. 1119.8 * 19.5 Feb.1722.6 * L. Buzzi (Wainscoat et al. 2012) Observation Model

10. P/2012 T1 (PANSTARRS) ANISOTROPIC MODEL I=80° Φ=260° Moreno et al. 2013 Nov.13 Nov.20 Dec.14 Jan.18 ACTIVE AREA AT LATITUDES [-90°,-45°] Observation Model (Equivalent to north hemisphere conf.)

11. ISOTROPIC ANISOTROPIC P/2012 T1 (PANSTARRS) on Dec. 14th, 2012

12. <2.2 kg/s Water production rate from HERSCHEL/HIFI (O’Rourke et al 2013) Moreno et al 2013 Nov 13, 2012 Dec 14, 2012 Nov 20, 2012 Jan 18, 2013 Feb 18, 2013 Feb 28, 2013 Broad size distribution, µm to cm range Power index -3.5 Terminal velocity v 1/r 1/2 ȣ

13. MBC P/2010 R2 (La Sagra) Moreno et al. 2011

14. 10.9 Oct 201016.0 Oct 201026.9 Oct 2010 04.8 Nov 201009.8 Jan 2011 ISOTROPIC EJECTION MODEL FOR P/2010 R2 (La Sagra) Moreno et al. 2011 Obs. Model

15. 10.9 Oct 201016.0 Oct 201026.9 Oct 2010 04.8 Nov 201009.8 Jan 2011 ANISOTROPIC EJECTION MODEL FOR P/2010 R2 (La Sagra) Moreno et al. 2011 Obs. Model

16. CONCLUSIONS FROM P/2012 T1 (PANSTARRS) MODELING - CLEAR SUSTAINED ACTIVITY PATTERN WITH DURATION 4-6 MONTHS, UNKNOWN MECHANISM, LIKELY WATER-ICE-DRIVEN ACTIVITY. - TOTAL EJECTED MASS: 5-30×10 6 kg - PARTICLE SIZE SIZE DISTRIBUTION (µm TO cm) WITH POWER LAW α = -3.5 - AN ANISOTROPIC EJECTION PATTERN WITH ACTIVE AREA AT LATITUDES [+45°,+90°] INTERVAL, OR [-90°,-45°] IS FAVORED - FOR THE ANISOTROPIC PATTERN, ROTATING AXIS IS NEAR THE ORBITAL PLANE, POINTING NEAR PERIHELION DIRECTION - SIMILAR PATTERN AS MBC P/2010 R2 (LA SAGRA) More details: Moreno et al., ApJ, 770, L30 (2013)