J/MNRAS/515/4551 NEA (2102) Tantalus light curves (Rozek+ 2022)
Physical properties of near-Earth asteroid (2102) Tantalus from
multi-wavelength observations.
Rozek A., Lowry S.C., Rozitis B., Dover L.R., Taylor P.A., Virkki A.,
Green S.F., Snodgrass C., Fitzsimmons A., Campbell-White J., Sajadian S.,
Bozza V., Burgdorf M.J., Dominik M., Figuera Jaimes R., Hinse T.C.,
Hundertmark M., Jorgensen U.G., Longa-Pena P., Rabus M., Rahvar S.,
Skottfelt J., Southworth J.
<Mon. Not. R. Astron. Soc. 515, 4551-4564 (2022)>
=2022MNRAS.515.4551R 2022MNRAS.515.4551R (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Minor planets ; Photometry
Keywords: techniques: photometric - techniques: radar astronomy -
minor planets - asteroids: individual: (2102) Tantalus -
methods: observational
Abstract:
Between 2010 and 2017 we have collected new optical and radar
observations of the potentially hazardous asteroid (2102) Tantalus
from the ESO NTT and Danish telescopes at the La Silla Observatory and
from the Arecibo planetary radar. The object appears to be nearly
spherical, showing a low amplitude light-curve variation and limited
large-scale features in the radar images. The spin-state is difficult
to constrain with the available data; including a certain light-curve
subset significantly changes the spin-state estimates, and the
uncertainties on period determination are significant. Constraining
any change in rotation rate was not possible, despite decades of
observations. The convex lightcurve-inversion model, with rotational
pole at lon=210±41° and lat=-30±35°, is more flattened
than the two models reconstructed by including radar observations:
with prograde (lon=36±23°, lat=30±15°), and with
retrograde rotation mode (lon=180±24°, lat=-30±16d°. Using
data from WISE we were able to determine that the prograde model
produces the best agreement in size determination between radar and
thermophysical modelling. Radar measurements indicate possible
variation in surface properties, suggesting one side might have lower
radar albedo and be rougher at centimetre-to-decimetre scale than the
other. However, further observations are needed to confirm this.
Thermophysical analysis indicates a surface covered in fine-grained
regolith, consistent with radar albedo and polarisation ratio
measurements. Finally, geophysical investigation of the spin-stability
of Tantalus shows that it could be exceeding its critical spin-rate
via cohesive forces.
Description:
We observed Tantalus primarily with the EFOSC2 camera on the 3.6m NTT
telescope at ESO's La Silla Observatory in Chile on 8 nights between
August 2010 and November 2013. These light curves were obtained under
ESO programme 185.C-1033.
We collected further optical light curves in June and July 2017 with
the Danish 1.54m telescope, also located at La Silla using the DFOSC
instrument. These observations were obtained as part of the MiNDSTEp
consortium that operates the Danish telescope for 6 months each year.
The table includes previously published photometry obtained at the
Bochum and Ondrejov observatories. The processed light curves were
retrieved from the NASA Planetary Data System.
The table also includes previously published photometry obtained at
the Palmer Divide Station. The processed light curves were retrieved
from the Asteroid Lightcurve Data Exchange Format (ALCDEF) database.
objects:
--------------------------------------------------------------
Planet Name H i e a
mag deg AU
--------------------------------------------------------------
2102 Tantalus 16.01 64.004662 0.29928139 1.29005830
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 83 32 *A chronological list of optical light curves of
asteroid (2102) Tantalus used in this study
tablea1.dat 32 1583 Near-Earth asteroid (2102) Tantalus optical
light curves
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Note on table1.dat: Each line represents a single light curve (sometimes a few
segments were observed on a single night).
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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- 2 I2 --- ID Light curve identification number
4- 14 A11 "date" Obs.date UT Date at the beginning of the night
16- 20 F5.3 AU Rh Hheliocentric distance
22- 26 F5.3 AU Delta Geocentric distance
28- 32 F5.2 deg alpha Solar phase angle
34- 38 F5.1 deg lambda0 Observer-centred ecliptic longitude
40- 44 F5.1 deg beta0 Observer-centred ecliptic latitude
46- 48 F3.1 h Total Length of the light curve
50- 53 F4.2 mag Ampl Apparent peak-to-peak amplitude
55- 58 A4 --- Filter Filter
60- 67 A8 --- Obs Observing facility used to obtain the
light curve (1)
69 A1 --- LC-subset [*] LC-subset note (2)
71 A1 --- LC+radar [*] LC+radar note (3)
73- 83 A11 --- Ref Reference (4)
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Note (1): Observing facility key (with MPC site code) as follows
Bochum = (Bochum, 809), European Southern Observatory 0.61m Bochum
telescope in La Silla, Chile
Ondrejov = (Ondrejov, 557), Academy of Sciences of the Czech Republic
Ondrejov Observatory 0.65m telescope, Czechia;
NTT = (NTT, 809), European Southern Observatory 3.58m New Technology
Telescope in La Silla, Chile
CS3-PDS = (PDS, U82), Palmer Divide Station (various telescopes with 0.3-0.5m
mirrors), California, USA
Danish = (Danish, 809), European Southern Observatory 1.54m Danish telescope
in La Silla, Chile.
Note (2): * if the shape modelling using light-curve inversion was done twice,
once using the full light-curve data set and one restricted to a subset of
light curves.
Note (3): * for the model combining radar data with optical light curves we used
a subset of the light curves from our observing campaign selected for SNR and
observing geometry coverage.
Note (4): References as follows:
Pravec1997b = 1997, Icarus, 130, 275
Warner2015 = 2015, Minor Planet Bulletin, 42, 79
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Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
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1- 14 F14.6 d JD Julian Date (no light-time correction)
16 A1 --- Filter [RVC] Filter (C for clear)
18- 23 F6.3 mag mag Relative magnitude
25- 29 F5.3 mag e_mag 1-sigma uncertainty in relative magnitude
31- 32 I2 --- ID [1/32] Lightcurve ID consistent with
Table 1 (1)
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Note (1): There are 32 lightcurves included in the file. Each light curve is
cleary marked in the last column, (see Table 1 in paper for a details of which
light curves are published and the references below)
(1) Pravec et al., 1997, Icarus, 130, 275
(2) Warner, 2015, Minor Planet Bulletin, 42, 79
(3) Warner, 2017, Minor Planet Bulletin, 44, 223
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Acknowledgements:
Agata Rozek, a.rozek(at)ed.ac.uk
(End) Patricia Vannier [CDS] 29-Jun-2022