TY - JOUR

T1 - A shape-and-density model of the putative binary EKBO 2001 QG298

AU - Takahashi, Shigeru

AU - Wing-Huen, I. P.

PY - 2004

Y1 - 2004

N2 - Recent observations of the Edgeworth-Kuiper belt object (EKBO) 2001 QG 298 (Sheppard, Jewitt 2004) have shown that the lightcurve of this object has a very large amplitude (1.14 ± 0.04mag), indicating that it is either of an elongated shape or of a binary structure with two components of similar sizes nearly in contact with each other. On the basis of these interesting published data, we employed Roche binary lightcurve simulations to construct a shape model of EKBO 2001 QG298. The shape parameters of the best-fitted model were 260 (164) × 205 (130) × 185 (116) km for the primary, and 265 (168) × 160 (102) × 150 (94) km for the secondary in the case of an albedo of 0.04 (0.10). An additional result of this calculation is that the average bulk density of the contact binary system could be estimated to be 630kgm-3. This value is similar to that of several icy moons of Saturn with a diameter of less than 200 km. We have also used the Jacobi ellipsoidal approximation to compute the shape of one of the largest EKBOs, Varuna. The corresponding shape parameters are a : b : c = 1.00 : 0.76 : 0.50. The lower limit of the bulk density is p ≥ 1000kgm-3. These results are in good agreement with the published values of Jewitt and Sheppard (2002), and are consistent with their suggestion that larger icy bodies have higher densities (Sheppard, Jewitt 2002).

AB - Recent observations of the Edgeworth-Kuiper belt object (EKBO) 2001 QG 298 (Sheppard, Jewitt 2004) have shown that the lightcurve of this object has a very large amplitude (1.14 ± 0.04mag), indicating that it is either of an elongated shape or of a binary structure with two components of similar sizes nearly in contact with each other. On the basis of these interesting published data, we employed Roche binary lightcurve simulations to construct a shape model of EKBO 2001 QG298. The shape parameters of the best-fitted model were 260 (164) × 205 (130) × 185 (116) km for the primary, and 265 (168) × 160 (102) × 150 (94) km for the secondary in the case of an albedo of 0.04 (0.10). An additional result of this calculation is that the average bulk density of the contact binary system could be estimated to be 630kgm-3. This value is similar to that of several icy moons of Saturn with a diameter of less than 200 km. We have also used the Jacobi ellipsoidal approximation to compute the shape of one of the largest EKBOs, Varuna. The corresponding shape parameters are a : b : c = 1.00 : 0.76 : 0.50. The lower limit of the bulk density is p ≥ 1000kgm-3. These results are in good agreement with the published values of Jewitt and Sheppard (2002), and are consistent with their suggestion that larger icy bodies have higher densities (Sheppard, Jewitt 2002).

KW - Kuiper Belt

KW - Minor planets, asteroids

KW - Planets and satellites: individual (Janus)

UR - http://www.scopus.com/inward/record.url?scp=12144281201&partnerID=8YFLogxK

U2 - 10.1093/pasj/56.6.1099

DO - 10.1093/pasj/56.6.1099

M3 - 期刊論文

AN - SCOPUS:12144281201

SN - 0004-6264

VL - 56

SP - 1099

EP - 1103

JO - Publications of the Astronomical Society of Japan

JF - Publications of the Astronomical Society of Japan

IS - 6

ER -