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Post Info TOPIC: Asteroid 136472 (2005 FY9)


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RE: Asteroid 136472 (2005 FY9)
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Title: Evidence of N2-Ice On the Surface of the Icy Dwarf Planet 136472 (2005 FY9)
Authors: S.C. Tegler, W.M. Grundy, F. Vilas, W. Romanishin, D. Cornelison, G.J. Consolmagno

We present high signal precision optical reflectance spectra of 2005 FY9 taken with the Red Channel Spectrograph and the 6.5-m MMT telescope on 2006 March 4 UT (5000 - 9500 A; 6.33 A pixel-1) and 2007 February 12 UT (6600 - 8500 A; 1.93 A pixel-1). From cross correlation experiments between the 2006 March 4 spectrum and a pure CH4-ice Hapke model, we find the CH4-ice bands in the MMT spectrum are blueshifted by 3 4 A relative to bands in the pure CH4-ice Hapke spectrum. The higher resolution MMT spectrum of 2007 February 12 UT enabled us to measure shifts of individual CH4-ice bands. We find the 7296 A, 7862 A, and 7993 A CH4-ice bands are blueshifted by 4 2 A, 4 4 A, and 6 5 A. From four measurements we report here and one of our previously published measurements, we find the CH4-ice bands are shifted by 4 1 A. This small shift is important because it suggest the presence of another ice component on the surface of 2005 FY9. Laboratory experiments show that CH4-ice bands in spectra of CH4 mixed with other ices are blueshifted relative to bands in spectra of pure CH4-ice. A likely candidate for the other component is N2-ice because its weak 2.15 micron band and blueshifted CH4 bands are seen in spectra of Triton and Pluto. Assuming the shift is due to the presence of N2, spectra taken on two consecutive nights show no difference in CH4/N2. In addition, we find no measurable difference in CH4/N2 at different depths into the surface of 2005 FY9.

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Asteroid 136472 (2005 FY9)
spacer.gif 2003 EL61 & 2003UB313

2003 EL61 and 2003UB313

orbits 52 AU from the Sun.
2005 FY9 is estimated to have an absolute magnitude of -0.4; with a Pluto-like albedo of 0.6 this would give it a diameter that is slightly less than the diameter of Pluto, about 1990km. But if it's darker (Sedna is ~ 0.1) then it could be a lot bigger.
Its orbit is inclined at 29 degrees to the solar plane, and has a Period of 308 years. It was discovered by Mike Brown.
It is currently in the constellation Coma Berenices
Orbital elements:
2005 FY9
Epoch 2005 Aug. 18.0 TT = JDT 2453600.5 MPC
M 213.91871 (2000.0) P Q
n 0.00319661 Peri. 245.84775 +0.70933335 +0.51938413
a 45.6397027 Node 79.41551 -0.32755355 +0.84151339
e 0.1518904 Incl. 28.99834 -0.62414330 +0.14864500
P 308 H 0.1 G 0.15 U 8
Residuals in seconds of arc
030201 644 0.6+ 0.7+ 050331 644 0.0 0.0 050331 644 0.1+ 0.0
030310 644 0.6- 0.8- 050331 644 0.1- 0.0 050405 644 0.2+ 0.1+
2005 FY9 is visually the second brightest Kuiper belt object, after Pluto, with an apparent magnitude of nearly 17.
Semi-major axis a 11018 million kilometres (45.64 AU)
Perihelion q 09345 million kilometres (38.71 AU)
Aphelion Q 12690 million kilometres (52.57 AU)
Inclination i 28.99834
Mean orbital speed
4.419 km/s
Orbital period P 112000 d (308 years)
Eccentricity e 0.1518904
Ascending node
79.41551
Mean anomaly M 213.91871
Argument of perihelion

245.84775


Three discoveries 2003 EL61, 2003 UB313 (18.9 magnitude at 96 AU, and an H of -1.1) and 2005 FY9 (absolute magnitude H =0.1)
Quaoar
, Orcus( 2004 DW ), and Sedna have H values of 2.6, 2.3 and 1.6, respectively.
Yes, click this! For List of Transneptunian Objects
Ephemeris:
2005 FY9                 a,e,i = 45.64, 0.15, 29                 q = 38.707
Date__(UT)__HR:MN R.A._(ICRF/J2000.0)_DEC APmag delta deldot S-O-T /r S-T-O

2006-Sep-17 00:00 12 20 51.26 +28 59 39.4 16.99 52.8409934292484 -0.9059376 28.4940 /T 0.5287
2006-Sep-27 00:00 12 21 43.56 +28 54 36.9 17.00 52.8232292246931 -5.2421687 30.4317 /T 0.5586

Yes, click this! For Past Daily Ephemeris


-- Edited by Blobrana at 14:07, 2008-01-22

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