* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Post Info TOPIC: Lightcurves of KBOs


L

Posts: 131433
Date:
Colours of minor bodies
Permalink  
 


Title: Colours of minor bodies in the outer solar system - II: A statistical analysis revisited
Authors: O. R. Hainaut, H. Boehnhardt, S. Protopapa

We present an update of the visible and near-infrared colour database of Minor Bodies in the Outer Solar System (MBOSSes), which now includes over 2000 measurement epochs of 555 objects, extracted from over 100 articles. The list is fairly complete as of December 2011. The database is now large enough to enable any dataset with a large dispersion to be safely identified and rejected from the analysis. The selection method used is quite insensitive to individual outliers. Most of the rejected datasets were observed during the early days of MBOSS photometry. The spectral gradient over the visible range is derived from the colours, as well as the R absolute magnitude M(1, 1). The average colours, absolute magnitude, and spectral gradient are listed for each object, as well as the physico-dynamical classes using a classification adapted from Gladman and collaborators. Colour-colour diagrams, histograms, and various other plots are presented to illustrate and investigate class characteristics and trends with other parameters, whose significances are evaluated using standard statistical tests. The colour tables and all plots are also available on the MBOSS colour web page this http URL which will be updated when new measurements are published.

Read more (303kb, PDF)



__________________


L

Posts: 131433
Date:
Kuiper Belt Objects
Permalink  
 


Title: High Albedos of Low Inclination Classical Kuiper Belt Objects
Authors: M. J. Brucker, W. M. Grundy, J. A. Stansberry, J. R. Spencer, S. S. Sheppard, E. I. Chiang, M. W. Buie
(Version v2)

We present observations of thermal emission from fifteen transneptunian objects (TNOs) made using the Spitzer Space Telescope. Thirteen of the targets are members of the Classical population: six dynamically hot Classicals, five dynamically cold Classicals, and two dynamically cold inner Classical Kuiper Belt Objects (KBOs). We fit our observations using thermal models to determine the sizes and albedos of our targets finding that the cold Classical TNOs have distinctly higher visual albedos than the hot Classicals and other TNO dynamical classes. The cold Classicals are known to be distinct from other TNOs in terms of their colour distribution, size distribution, and binarity fraction. The Classical objects in our sample all have red colours yet they show a diversity of albedos which suggests that there is not a simple relationship between albedo and colour. As a consequence of high albedos, the mass estimate of the cold Classical Kuiper Belt is reduced from approximately 0.01 Earth masses to approximately 0.001 Earth masses. Our results also increase significantly the sample of small Classical KBOs with known albedos and sizes from 21 to 32 such objects.

Read more (1547kb. PDF)

__________________


L

Posts: 131433
Date:
RE: Lightcurves of KBOs
Permalink  
 


Title: Light Curves of Dwarf Plutonian Planets and other Large Kuiper Belt Objects: Their Rotations, Phase Functions and Absolute Magnitudes
Authors: Scott S. Sheppard

I report new light curves and determine the rotations and phase functions of several large Kuiper Belt objects, including the dwarf planet Eris (2003 UB313). (120348) 2004 TY364 shows a light curve which if double-peaked has a period of 11.700.01 hours and peak-to-peak amplitude of 0.220.02 magnitudes. (84922) 2003 VS2 has a well defined double-peaked light curve of 7.410.02 hours with a 0.210.02 magnitude range. (126154) 2001 YH140 shows variability of 0.210.04 magnitudes with a possible 13.250.2 hour single-peaked period. The seven new KBOs in the sample which show no discernible variations within the uncertainties on short rotational time scales are 2001 UQ18, (55565) 2002 AW197, (119979) 2002 WC19, (120132) 2003 FY128, (136108) Eris 2003 UB313, (90482) Orcus 2004 DW, and (90568) 2004 GV9. The three medium to large sized Kuiper Belt objects 2004 TY364, Orcus and 2004 GV9 show fairly steep linear phase curves (~0.18 to 0.26 mags per degree) between phase angles of 0.1 and 1.5 degrees. The extremely large dwarf planet Eris (2003 UB313) shows a shallower phase curve (0.090.03 mags per degree) which is more similar to the other known dwarf planet Pluto. It appears the surface properties of the largest dwarf planets in the Kuiper Belt maybe different than the smaller Kuiper Belt objects. This may have to do with the larger objects ability to hold more volatile ices as well as sustain atmospheres. The absolute magnitudes obtained from the phase slopes are several tenths of magnitudes different than from the MPC.

Read more (267kb, PDF)

__________________


L

Posts: 131433
Date:
KBO Satellites
Permalink  
 


Satellites have been discovered around three TNOs; 2003 AZ_84, (50000) Quaoar, (55637) 2002 UX_25, and (90482) Orcus. .

IAUC 8812, 2007 Feb. 22.

__________________


L

Posts: 131433
Date:
Lightcurves of KBOs
Permalink  
 


Lightcurves of 20--100 kilometre Kuiper Belt Objects using the Hubble Space Telescope
Authors: David E. Trilling, Gary M. Bernstein


Researchers report high precision photometry of three small and one larger Kuiper Belt Objects (KBOs) obtained with the Advanced Camera for Surveys onboard the Hubble Space Telescope (ACS/HST).
The three small bodies are the smallest KBOs for which lightcurve measurements are available.
2003 BF91 has a diameter of 20 kilometres (assuming 10% albedo) and a 1.09 magnitude, 9.1-hour lightcurve that is feasibly explained by the rotation of an elongated, coherent body that is supported by material strength and best imagined as an icy outer Solar System analogy to asteroid (243) Ida.
Two other small KBOs, 2003 BG91 and 2003 BH91 (diameters 31 and 18 km, with albedo 10%), exhibit an unremarkable lightcurve and no detectable photometric variation, respectively.
For the larger KBO 2000 FV53 (116 km diameter, assuming 10% albedo) they strongly detected a non-sinusoidal periodic (7.5 hours) brightness variation with a very small amplitude (0.07 mag). This KBO may be nearly spherical, a result that might not be unusual in the Kuiper Belt but would be remarkable among outer Solar System satellites of similar size.
They carry out a study of possible physical states and bulk densities under the assumptions of both fluid equilibrium and finite, non-zero internal friction. The densities for the these KBOs are likely to be in the range 1--2 g/cm3, and a plausible solution for 2000 FV53 is a rubble pile of this density that is held slightly out of the minimum-energy shape by internal friction among constituent blocks that are relatively small.
Their interpretation of 2000 FV53 as a pulverized but essentially primordial object and 2003 BF91 as a collisional fragment is consistent with models of collisional timescales in the outer Solar System.
They compile all published KBO lightcurve data and compare their results to the larger population.


The best-fit periods are marked with the arrows, as are other peaks of note, in parentheses. 2003 BG91 (black) has a suite of solutions, of which the best has a period of 4.2 hours; the others correspond to periods of 4.5 and 4.9 hours. 2003 BF91 (red) has a secondary, non-resonant peak at 7.3 hours that is nearly as satisfactory a fit as the best fit. The best-fit solution for 2003 BH91 (green) is not significant and is therefore marked in parentheses. The best-fit
period for 2000 FV53 (blue) is 7.5 hours; a solution that is nearly as significant is found with a period of 3.79 hours, almost exactly half the best-fit solution.



Read More (PDF)

__________________
Page 1 of 1  sorted by
Quick Reply

Please log in to post quick replies.



Create your own FREE Forum
Report Abuse
Powered by ActiveBoard