J/AJ/157/228 Cold Classical TNOs: LCs & rotational properties (Thirouin+, 2019)
Light curves and rotational properties of the pristine Cold Classical
Kuiper Belt objects.
Thirouin A., Sheppard S.S.
<Astron. J., 157, 228 (2019)>
=2019AJ....157..228T 2019AJ....157..228T (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Minor planets ; Photometry ; Optical ;
Photometry, infrared
Keywords: Kuiper belt objects: individual (2004 VC 131, 2004 MU 8, 2004 VU 75) ;
techniques: photometric
Abstract:
We present a survey of the rotational and physical properties of the
dynamically low inclination Cold Classical (CC) trans-Neptunian objects
(TNOs). The CCs are primordial planetesimals and contain information about
our solar system and planet formation over the first 100 million years
after the Sun's formation. We obtained partial/complete light curves
for 42 CCs. We use statistical tests to derive general properties about
the shape and rotational frequency distributions of the CCs and infer
that they have slower rotations and are more elongated/deformed than
the other TNOs. On the basis of the full light curves, the mean rotational
period of the CCs is 9.48±1.53 hr compared to 8.45±0.58 hr for the
rest of the TNOs. About 65% of the TNOs have a light-curve amplitude below
0.2 mag compared to the 36% of CCs with small amplitude. We present the
full light curve of one likely contact binary, 2004 VC131, with a
potential density of 1 g/cm3 for a mass ratio of 0.4. We have hints
that 2004 MU8 and 2004 VU75 are perhaps potential contact binaries, on
the basis of their sparse light curves, but more data are needed to confirm
this finding. Assuming equal-sized binaries, we find that ∼10%-25% of
the CCs could be contact binaries, suggesting a deficit of contact binaries
in this population compared to previous estimates and to the (∼40%-50%)
possible contact binaries in the Plutino population. These estimates are
lower limits and may increase if nonequal-sized contact binaries are
considered. Finally, we put in context the results of the New Horizons
flyby of 2014 MU69.
Description:
Our two main facilities are the Magellan-Baade telescope and the Lowell's
Discovery Channel Telescope (DCT). At Las Campanas Observatory (Chile),
the 6.5 m Magellan-Baade telescope is equipped with IMACS
(Inamori-Magellan Areal Camera & Spectrograph). This instrument is a
wide-field imager with a 27.4' diameter field (8 CCDs) and a pixel scale
of 0.20"/pixel. The short camera mode was used for all our runs. The
Lowell's DCT (Happy Jack, Arizona) is equipped with the Large Monolithic
Imager (LMI), a 6144x6160 pixels CCD (Levine et al. 2012SPIE.8444E..19L 2012SPIE.8444E..19L).
The field of view is 12.5'x12.5', and 0.12"/pixel is the pixel scale.
We use a range of exposure times between 250 and 900 s, depending on the
telescope, the weather conditions, and the filter. Generally, broadband
filters are selected to maximize the signal-to-noise ratio of the TNO
(VR filter at DCT and WB4800-7800 filter at Magellan). Both filters
cover a similar range, near 500-800 nm.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 98 43 Periodicity and amplitude findings
table1.dat 90 91 Orbital parameters and observing circumstances
of Cold Classicals (CCs) observed for this work
table3.dat 57 643 Photometry used in this paper
--------------------------------------------------------------------------------
See also:
J/A+A/522/A93 : Short-term variability of 29 minor planets (Thirouin+, 2010)
J/A+A/569/A3 : Rotational properties of TNOs (Thirouin+, 2014)
J/AJ/154/62 : Orbital parameters of Kuiper Belt objects (Volk+, 2017)
J/AJ/154/241 : Photometry of a Kuiper Belt object: 2002 CC249
(Thirouin+, 2017)
http://minorplanetcenter.net/ : MPC database
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 29 A29 --- TNO Trans-Neptunian object (TNO) name
31 A1 --- m_TNO [AB] Multiplicity index on TNO
33 I1 --- Flag [1]? Rotation period flag (1)
35 A1 --- l_Per [>] Limit flag on Per
36- 40 F5.2 h Per [1.1/15.7]? Periodicity
42 A1 --- l_Dmag [>] Limit flag on dmag
43- 46 F4.2 mag Dmag [0.08/0.55] Full lightcurve amplitude Δm
48- 51 F4.2 mag e_Dmag [0.04]? Uncertainty in Dmag
52 A1 --- u_Dmag [:] Uncertainty flag on Dmag (:=approximate value)
54- 63 F10.5 d phi0 [7230.85274/8342.83471]? Zero phase without
light-time correction (JD-2450000) φ0
65- 67 F3.1 mag HMag [5.0/7.2]? MPC H absolute magnitude
69- 71 I3 km D0.04 [241/665]? Diameter, assuming albedo of 0.04
73- 75 I3 km D0.20 [108/297]? Diameter, assuming albedo of 0.20
77- 98 A22 --- Res Resolved binary status (2)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
1 = 2004 VU75 has potential rotational periods of 8.46h, 10.2h, or 12.9h.
Note (2): This field indicates if the object is a known or not resolved binary
(Noll et al. 2008Icar..194..758N 2008Icar..194..758N; Stephens & Noll 2006AJ....131.1142S 2006AJ....131.1142S). Some
objects have not been observed for companion search (to our knowledge), thus
it is unknown if they are binary or not and we used a question mark to
identify them.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 29 A29 --- TNO TNO name
31- 36 F6.3 AU a [42.098/48.029] Minor Planet Center (MPC)
semi-major axis
38- 42 F5.3 --- e [0.022/0.191] MPC eccentricity
44- 46 F3.1 deg i [0.2/9.7] MPC inclination
48- 57 A10 "date" Date UT observation date
59- 60 I2 --- Nobs [1/27] Number of observations
62- 67 F6.3 AU Delta [37.438/47.259] Geocentric distance, Δ
69- 74 F6.3 AU rh [38.275/47.638] Heliocentric distance
76- 78 F3.1 deg alpha [0/1.3] Phase angle, α
80- 81 A2 --- Filt [VR r'] Filter used
83- 90 A8 --- Tel Telescope used (Magellan or DCT)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 29 A29 --- TNO TNO name
31 A1 --- m_TNO [AB] Multiplicity index on TNO
33- 45 F13.5 d JD Julian Date of observation without light-time
correction
47- 52 F6.3 mag omag [-0.54/0.44] Relative observed magnitude
54- 57 F4.2 mag e_omag [0.02/0.18] Uncertainty in omag
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 13-Aug-2019