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Detection of Cometary Activity of (60558) 174P/Echeclus. Young-Jun Choi (JPL) Paul Weissman (JPL). 174P/Echeclus. 2005 Dec 30.5UT Palomar. 2006 Apr 20.5UT Palomar. (60558) 2000 EC98. Discovery: 2000 Mar 3 by SpaceWatch
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Detection of Cometary Activity of (60558) 174P/Echeclus Young-Jun Choi (JPL) Paul Weissman (JPL)
174P/Echeclus 2005 Dec 30.5UT Palomar
(60558) 2000 EC98 • Discovery: 2000 Mar 3 by SpaceWatch • Orbit: a=10.759AU, e=0.455, q=5.86AU, Q=15.65AU, i=4.3o • B-V=0.760.15, V-R=0.51~0.55 0.09 P=26.8hr (Rousselot et al. 2005) • V-R=0.470.06, V-I=0.500.06(Bauer et al. 2003) • Albedo(v)=0.046(0.035-0.063), D=85(73-97) km (Stansberry et al.) • Spectroscopy(2001 Apr 27, Lazzarin et al)
Dec 30, 2005 Apr 20, 2006
Characteristics • 2006 Jan 30 (TMO; r ~ 10”) V=17.53, (B-V)=0.78, (V-R)=0.54, (V-I)=0.93 • 2006 Apr 20 (Palomar; r ~ 10”) V=17.26, (B-V)=0.75, (V-R)=0.43, (V-I)=0.90 • Rousselot : (B-V)=0.76, (V-R)=0.51-0.55 • Bauer : (V-R)=0.47, (V-I)=0.97 • Surface Brightness Profile
Slope = -3 Slope = -6 2006 Apr 20 2005 Dec 30
Expansion Velocity: V ~ 500 – 800 m/s V(DI) ~ 100 (Ipatov), 230 m/s (Schleicher) V(Hale-Bopp, P/SW1) ~ 50 m/s Tth ~ 280K, vs ~ 350 m/s 2005 Dec 30
Dust Production • Assuming dust grain of radius=1m, albedo = 0.04, density = 1 cm-3
V-R -0.007 B-V -0.0008 R-I 2005 Dec 30 +0.0048 V-R B-V 0.0 R-I 2006 Apr 20
Past activity search • SpaceWatch, NEAT,Bauer,Rousselot • 2004 (Apr, Jun) • 2003 (Apr , May) • 2002 (Jan, Feb,Mar, Apr, May,Jun) • 2001 (Feb, Mar,Apr , May, Dec) • 2000 (Jan, Feb,Mar, Apr, May) • 1998 (Jan, Feb, Apr) • 1997 (Jan, Apr) • 1996 (Feb) • Active coma: 2000 Jan 27, Feb 5
Spacewatch Archive 2000 Mar 03 2000 Feb 05 2000 Jan 27
Summary • 174P/Echeclus is unique since physical properties is known before its activity. • High expansion velocity and high dust production rate • The activity is repeated and activity on Dec 2005 is very fresh
Reason for Activity • Collision: Low probability among Centaurs • Outburst: • No water ice sublimation • Sublimation of highly volatile gases (CO, CH4,) • Timescale(~107 yr), production rate • By crystallization of amorphous ice
Jan – Jun 2006 • Jan 1 (Wise), 30 (TMO) • Feb 04, 09 (TMO) • Feb 24, 25, 26 (Spitzer, BOAO, TMO, Palomar) • Mar 19 (HST) • Apr 20, 22 (Palomar) • May 2-4 (VATT) • Jun 10 (VATT)