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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
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TheDustEnvironment of Main-BeltComet 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
MBCs: • New cometreservoir ? • Most are dynamicallystable ≈100 Myr • Recurrentactivity • Earth’swatercontribution P/2013 P5 New !!
A missionproposalisbeingpreparedtobesubmittedtothenextESA’s M4 call: CASTALIA: A MISSION TO A MAIN-BELT COMET • 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 See poster byBoehnhardtet al.
OBSERVATIONS OF P/2012 T1 (PANSTARRS) Roque de los Muchachos Observatory, La Palma GTC WHT Seeingconditions: 0.9”-1.1”
P/2012 T1 (PANSTARRS) OSIRIS@GTC PFIP@WHT Red bandpasses Nov 20, 2012 Nov 13, 2012 Feb 18, 2013 Dec 14, 2012 Jan 18, 2013 Moreno et al. ApJL 2013 in press Moreno et al. 2013
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)=v1(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
Observation Model
Nov.13 Nov.20 P/2012 T1 (PANSTARRS) ISOTROPIC MODEL Observation Model *L. Buzzi (Wainscoat et al. 2012) Jan.18 Dec.14 Moreno et al. 2013
Observation Model Nov.13 Nov.20 P/2012 T1 (PANSTARRS) ANISOTROPIC MODEL ACTIVE AREA AT LATITUDES [-90°,-45°] (Equivalenttonorthhemisphere conf.) I=80° Φ=260° Jan.18 Dec.14 Moreno et al. 2013
P/2012 T1 (PANSTARRS) onDec. 14th, 2012 ISOTROPIC ANISOTROPIC
Broadsizedistribution, µm to cm range Powerindex -3.5 Terminal velocity v 1/r1/2 ȣ Feb 28, 2013 Nov 13, 2012 Nov 20, 2012 Jan 18, 2013 Feb 18, 2013 Dec 14, 2012 Moreno et al 2013 <2.2 kg/s Waterproductionratefrom HERSCHEL/HIFI (O’Rourke et al 2013)
MBC P/2010 R2 (La Sagra) Moreno et al. 2011
ISOTROPIC EJECTION MODEL FOR P/2010 R2 (La Sagra) 10.9 Oct 2010 16.0 Oct 2010 26.9 Oct 2010 Obs. Model 04.8 Nov 2010 09.8 Jan 2011 Moreno et al. 2011
ANISOTROPIC EJECTION MODEL FOR P/2010 R2 (La Sagra) 10.9 Oct 2010 16.0 Oct 2010 26.9 Oct 2010 Obs. Model 04.8 Nov 2010 09.8 Jan 2011 Moreno et al. 2011
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: 5-30×106 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)