the dust environment of main-belt comet p/2012 t1 (pan-starrs) moreno, f.(1); cabrera-lavers,...
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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(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 comet reservoir ?• Most are dynamically stable ≈100 Myr• Recurrent activity• Earth’s water contribution
P/2013 P5
New !!
• 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.
OBSERVATIONS OF P/2012 T1 (PANSTARRS)Roque de los Muchachos Observatory, La Palma
DATE (UT) DAYS AFTER PER.
Tp=2012/09/10.9INSTRUM./TELESC. RESOLUTION m(1,1,0)
2012 Nov 13.1 63.2 PFIP/WHT 4.2m 265.8 km/px 16.9±0.2
2012 Nov 20.0 70.1 OSIRIS/GTC 10.4m 274.8 km/px 17.0±0.2
2012 Dec 13.9 94.0 OSIRIS/GTC 10.4m 307.1 km/px 17.3±0.2
2013 Jan 17.9 129.0 OSIRIS/GTC 10.4m 385.4 km/px 17.7±0.2
2013 Feb 17.9 160.0 OSIRIS/GTC 10.4m 466.4 km/px 18.9±0.2
2013 Feb 27.9 170.0 LIRIS/WHT 4.2m 485.0 km/px KS ≥22.8±0.1
2013 Feb 27.9 170.0 ACAM/WHT 4.2m 485.0 km/px --
Seeing conditions: 0.9”-1.1”
GTCWHT
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, 2012 Jan 18, 2013
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≥22)SIZE DISTRIBUTION: n(r)=Cr-α, GRAINS DISTRIBUTED IN SIZES FROM µm TO cm 3)MASS LOSS RATE4)EJECTION PATTERN
COMPARE SYNTHETIC TAIL WITH OBSERVATIONS AND COMPUTE STANDARD DEVIATION
ObservationModel
P/2012 T1(PANSTARRS)
ISOTROPICMODEL
Moreno et al. 2013
Nov.13 Nov.20
Dec.14 Jan.18
mR(Observed) mR(Model)
Oct. 11 19.8* 19.5
Feb.17 22.6 22.6*L. Buzzi (Wainscoat et al. 2012)
ObservationModel
P/2012 T1(PANSTARRS)
ANISOTROPICMODEL
I=80°Φ=260°
Moreno et al. 2013
Nov.13 Nov.20
Dec.14 Jan.18
ACTIVE AREA AT LATITUDES [-90°,-45°]
ObservationModel
(Equivalent to north hemisphere conf.)
ISOTROPIC ANISOTROPIC
P/2012 T1 (PANSTARRS) on Dec. 14th, 2012
<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 rangePower index -3.5Terminal velocity v 1/r1/2 ȣ
MBC P/2010 R2(La Sagra)
Moreno et al. 2011
10.9 Oct 2010 16.0 Oct 2010 26.9 Oct 2010
04.8 Nov 2010 09.8 Jan 2011
ISOTROPIC EJECTION MODEL FOR P/2010 R2 (La Sagra)
Moreno et al. 2011
Obs.Model
10.9 Oct 2010 16.0 Oct 2010 26.9 Oct 2010
04.8 Nov 2010 09.8 Jan 2011
ANISOTROPIC EJECTION MODEL FOR P/2010 R2 (La Sagra)
Moreno et al. 2011
Obs.Model
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)