J/A+A/522/A93 Short-term variability of 29 minor planets (Thirouin+, 2010)
Short-term variability of a sample of 29 trans-Neptunian objects and Centaurs.
Thirouin A., Ortiz J.L., Duffard R., Santos-Sanz P., Aceituno F.J.,
Morales N.
<Astron. Astrophys. 522, A93 (2010)>
=2010A&A...522A..93T 2010A&A...522A..93T
ADC_Keywords: Minor planets ; Photometry
Keywords: Kuiper Belt: general - techniques: photometric
Abstract:
We present results of 6 years of observations, reduced and analyzed
with the same tools in a systematic way. We present completely new
data on 15 objects (1998SG35, 2002GB10, 2003EL61, 2003FY128, 2003MW12,
2003OP32, 2003WL7, 2004SB60, 2004UX10, 2005CB79, 2005RM43, 2005RN43,
2005RR43, 2005UJ438, 2007UL126 (or 2002KY14)), for 5 objects we
present a new analysis of previously published results plus additional
data (2000WR106, 2002CR46, 2002TX300, 2002VE95, 2005FY9) and for 9
objects we present a new analysis of data already published (1996TL66,
1999TZ1, 2001YH140, 2002AW197, 2002LM60, 2003AZ84, 2003CO1, 2003VS2,
2004DW). Lightcurves, possible rotation periods and photometric
amplitudes are reported for all of them. The photometric variability
is smaller than previously thought: the mean amplitude of our sample
is 0.1mag and only around 15% of our sample has a larger variability
than 0.15mag. The smaller variability than previously thought seems to
be a bias of previous observations. We find a very weak trend of
faster spinning objects towards smaller sizes, which appears to be
consistent with the fact that the smaller objects are more
collisionally evolved, but could also be a specific feature of the
Centaurs, the smallest objects in our sample.We also find that the
smaller the objects, the larger their amplitude, which is also
consistent with the idea that small objects are more collisionally
evolved and thus more deformed. Average rotation rates from our work
are 7.5h for the whole sample, 7.6h for the TNOs alone and 7.3h for
the Centaurs. All of them appear to be somewhat faster than what one
can derive from a compilation of the scientific literature and our own
results. Maxwellian fits to the rotation rate distribution give mean
values of 7.5h (for the whole sample) and 7.3h (for the TNOs only).
Assuming hydrostatic equilibrium we can determine densities from our
sample under the additional assumption that the lightcurves are
dominated by shape effects, which is likely no realistic. The
resulting average density is 0.92g/cm3 which is not far from the
density constraint that one can derive from the apparent spin barrier
that we observe.
Description:
The time series photometry of all the objects is provided as Table 3.
We highlighted in bold face the times corresponding to the images that
we used to obtain an R magnitude calibration. The rest of the R
magnitudes in the table was obtained by using the relative magnitude
information. Also, in table 1 are geometric data such as geocentric
and heliocentric distances. The R magnitudes that the TNOs would have
if they were at 1AU from the Earth and the Sun (mR(1,1)) are also
shown. No phase corrections were applied.
In table 3, we present our photometric results: the name of the object
and for each image we specify the Julian date (not corrected for
travel time), the Relative magnitude [mag] and the 1-sigma error
associated [mag], the R magnitude [mag], the filter used during
observational runs, the phase angle (phi) [deg], topocentric (rh)
and heliocentric (Delta) distances [AU] and the magnitude [mag] at 1AU
from the Earth and at 1AU from the Sun. We highlight in bold face the
date of the image in which we performed a crude absolute calibration.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 63 29 List of studied objects
table1.dat 69 239 Dates, geometric and photometric data of the
observations
table3.dat 87 5377 Photometric results
table3.tex 572 5386 Latex version of the table
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See also:
B/astorb : Orbits of Minor Planets (Bowell+ 2010)
J/A+A/468/L13 : Photometry of the trans-Neptunian object 2005FY9 (Ortiz+, 2007)
J/AJ/133/26 : Solar phase curves of distant icy bodies (Rabinowitz+, 2007)
J/A+A/508/451 : Light curves of 5 Trans-Neptunian Objects (Perna+, 2009)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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2- 7 I6 --- Planet ? Planet number, if assigned (G1)
10- 19 A10 --- Name Planet name (G1)
25- 29 F5.2 mag H ? Absolute magnitude H parameter
32- 40 F9.6 deg i ? Orbit inclination
42- 51 F10.8 --- e ? Orbit eccentricity
53- 63 F11.8 AU a ? Orbit semimajor axis
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Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
2- 7 I6 --- Planet ? Planet number, if assigned (G1)
10- 19 A10 --- Name Planet name (G1)
24- 33 A10 "DD/MM/YYYY" Date Observation date
35- 37 I3 --- Nimg Number of images
39- 44 F6.3 AU rh Topocentric distance
46- 51 F6.3 AU delta Heliocentric distance
53- 56 F4.2 deg phi Phase angle
58 A1 --- Filt [R] Filter used
60- 69 A10 --- Tel Telescope: Calar Alto, INT or OSN (1)
-------------------------------------------------------------------------------
Note (1): Telescopes are:
Calar Alto = 2.2m at Calar Alto Obs. (Almeria, Spain)
INT = 2.5m Isaac Newton Telescope at El Roque de Los Muchachos (Spain)
OSN = 1.5m telescope at Sierra Nevada Obs. (Granada, Spain)
-------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
2- 7 I6 --- Planet ? Planet number, if assigned (G1)
10- 19 A10 --- Name Planet name (G1)
23 A1 --- n_JD [*] * for the date of the image in which we
performed a crude absolute calibration
25- 37 F13.5 d JD Julian date, not corrected for travel time
39- 44 F6.3 mag relmag Relative magnitude
46- 50 F5.3 mag e_relmag 1-σ error associated to relmag
52- 56 F5.2 mag Rmag R magnitude
58- 62 A5 --- Filter Filter used during observational runs
(Clear or R)
64- 67 F4.2 deg phi Phase angle
69- 74 F6.3 AU rh Topocentric distance
76- 81 F6.3 AU delta Heliocentric distance
83- 87 F5.2 mag mR(1,1) Magnitude at 1AU from the Earth and at 1AU
from the Sun
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Global notes:
Note (G1): Planet names and numbers as in the "Astorb" data-base
(Cat. B/astorb)
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Acknowledgements:
Audrey Thirouin, thirouin(at)iaa.es
(End) Patricia Vannier [CDS] 27-Aug-2010