J/A+A/631/A2 List of new asteroid models (Durech+, 2019)
Inversion of asteroid photometry from Gaia DR2 and the Lowell Observatory
photometric database.
Durech J., Hanus J., Vanco R.
<Astron. Astrophys. 631, A2 (2019)>
=2019A&A...631A...2D 2019A&A...631A...2D (SIMBAD/NED BibCode)
ADC_Keywords: Photometry ; Minor planets
Keywords: minor planets - asteroids: general - methods: data analysis -
techniques: photometric
Abstract:
Rotation properties (spin-axis direction and rotation period) and
coarse shape models of asteroids can be reconstructed from their
disk-integrated brightness when measured from various viewing
geometries. These physical properties are essential for creating a
global picture of structure and dynamical evolution of the main belt.
The number of shape and spin models can be increased not only when new
data are available, but also by combining independent data sets and
inverting them together. Our aim was to derive new asteroid models by
processing readily available photometry.
We used asteroid photometry compiled in the Lowell Observatory
photometry database with photometry from the Gaia Data Release 2. Both
data sources are available for about 5400 asteroids. In the framework
of the Asteroids@home distributed computing project, we applied the
light curve inversion method to each asteroid to find its convex shape
model and spin state that fits the observed photometry.
Due to the limited number of Gaia DR2 data points and poor photometric
accuracy of Lowell data, we were able to derive unique models for only
∼1100 asteroids. Nevertheless, 762 of these are new models that
significantly enlarge the current database of about 1600 asteroid
models.
Our results demonstrate the importance of a combined approach to
inversion of asteroid photometry. While our models in general agree
with those obtained by separate inversion of Lowell and Gaia data, the
combined inversion is more robust, model parameters are more
constrained, and unique models can be reconstructed in many cases when
individual data sets alone are not sufficient.
Description:
Table A.1: List of new asteroid models. For each asteroid, we list one
or two pole directions in the ecliptic coordinates (λ, β),
the sidereal rotation period P, the rotation period PLCDB from the
LCDB and its quality code U (if available), the number of sparse
photometric data points NL and NG in the Lowell database and Gaia DR2,
respectively, and the method which was used to derive the rotation
period: C - convex models, E - ellipsoids, CE - both methods gave the
same unique period. The accuracy of the sidereal rotation period P is
of the order of the last decimal place given. For some asteroids, the
LCDB contains a note about the rotation state or binarity: Here A
means an ambiguous period; B stands for a binary system; T means
tumbling - a non-principal-axis rotation; T0 means that the
theoretical tumbling damping time scale (Pravec et al.,
2014Icar..233...48P 2014Icar..233...48P ) is long enough that tumbling might be expected,
but observations are not sufficient to substantiate either tumbling or
not tumbling; T- means that the tumbling damping time scale is long
enough that tumbling might be expected, but observations indicate that
the object is not tumbling; and T+ indicates that the tumbling damping
time scale is short enough that tumbling would not seem likely,
however observations indicate that it may be tumbling or actually is
tumbling.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 92 762 List of new asteroid models
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Number Asteroid number
9- 28 A20 --- Name Asteroid name or designation
30- 32 D3.2 deg ELON1 Ecliptic pole longitude (J2000.0) for model 1,
lambda1
34- 36 D3.2 deg ELAT1 Ecliptic pole latitude (J2000.0) for model 1,
beta1
39- 41 D3.2 deg ELON2 [0/360]? Ecliptic pole longitude (J2000.0) for
model 2, lambda2
43- 45 D3.2 deg ELAT2 ? Ecliptic pole latitude (J2000.0)
for model 2, beta2
48- 57 F10.6 h P Sidereal period of rotation
61 A1 --- l_PLCDB Limit flag on PLCDB
62- 70 F9.5 h PLCDB ? Rotation period in the LCDB
72- 73 A2 --- u_PLCDB [123± ] Uncertainty code according to LCDB
76- 77 A2 --- Note ? Note according to LCDB
81- 83 I3 --- NL Number of Lowell photometric points
86- 87 I2 --- NG Number of Gaia photometric points
91- 92 A2 --- Method Method used for period determination (1)
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Note (1): The method which was used to derive the unique rotation period
as follows:
C = convex inversion
E = ellipsoids
CE = both methods gave the same unique period
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Acknowledgements:
Josef Durech, durech(at)sirrah.troja.mff.cuni.cz
(End) Josef Durech [Charles Univer. Prague], Patricia Vannier [CDS] 13-Sep-2019