J/ApJS/259/7 FOSSIL. II. Subaru/HSC light curves of Hildas (Chang+, 2022)
FOSSIL.
II. The rotation periods of small-sized Hilda asteroids.
Chang C.-K., Chen Y.-T., Fraser W.C., Lehner M.J., Wang S.-Y.,
Alexandersen M., Choi Y.-J., Granados Contreras A.P., Ito T., JeongAhn Y.,
Ji J., Kavelaars J.J., Kim M.-J., Lawler S.M., Li J., Lin Z.-Y.,
Lykawka P.S., Moon H.-K., More S., Munoz-Gutierrez M., Ohtsuki K.,
Pike R.E., Terai T., Urakawa S., Yoshida F., Zhang H., Zhao H., Zhou J.-L.,
The FOSSIL Collaboration
<Astrophys. J. Suppl. Ser., 259, 7 (2022)>
=2022ApJS..259....7C 2022ApJS..259....7C
ADC_Keywords: Minor planets; Photometry; Optical; Surveys
Keywords: Hilda group ; Period determination ; Asteroid rotation
Abstract:
Using the high-cadence lightcurves collected from the FOSSIL survey,
rotation periods of 17 small (diameter 1km<D<3km) Hilda asteroids
(hereinafter Hildas) were obtained. Combined with the previously
measured rotation periods of Hildas, a spin-rate limit appears at
around 3hr. Assuming rubble-pile structures for the Hildas, a bulk
density of ∼1.5g/cm3 is required to withstand this spin-rate limit.
This value is similar to that of the C-type asteroids (1.33g/cm3)
and higher than the ∼1g/cm3 bulk density of the Jupiter Trojans.
This suggests that the Hildas population may contain more C-type
asteroids than expected, and the limit at 3hr simply reflects the
spin-rate limit for C-type asteroids. In addition, a Hilda superfast
rotator was found, which has a rotation period of 1.633hr and an
estimated diameter of 0.7km. This object is unlikely to be explained
by a rubble-pile or monolithic structure.
Description:
In this paper, we report the results from analysis of lightcurves of
kilometer-sized Hildas collected from the Formation of the Outer Solar
System: An Icy Legacy (FOSSIL) survey to measure their rotation
periods and identify the possible spin-rate limit of Hildas.
High-cadence observations were performed using Subaru/Hyper
Suprime-Cam (HSC) on four blocks of pointings during 2019 April 10
(19Apr), 2020 May 18-19 (20May), 2020 August 20-22 (20Aug), and
2020 October 13-16 (20Oct). The g-band filter was used for the 19Apr
observations, and the r2 band was used for the other three blocks.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 67 679 Photometric measurements for Hilda data
presented in this paper
table3.dat 99 17 Physical parameters of the Formation of the Outer
Solar System: An Icy Legacy (FOSSIL) Hildas for
which rotation periods were obtained
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See also:
J/ApJ/744/197 : WISE/NEOWISE observations of Hilda asteroids (Grav+, 2012)
J/A+A/568/L7 : Reflectance spectra of 12 Trojans and Hildas (Marsset+, 2014)
J/ApJS/219/27 : Surveys of asteroid rotation periods using iPTF (Chang+, 2015)
J/ApJS/227/20 : Rotation periods of asteroids using iPTF (Chang+, 2016)
J/AJ/153/116 : Trojan asteroids in the Kepler campaign 6 field (Ryan+, 2017)
J/ApJS/241/6 : Searching for super-fast rotators using PS1 (Chang+, 2019)
J/ApJS/254/7 : Kepler light curves of Jovian Trojan asteroids (Kalup+, 2021)
http://www.minorplanet.info/php/lcdb.php : MinorPlanet.info LC database
http://www.fossil-survey.org/ : FOSSIL home page
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- FOSSIL FOSSIL survey identifier
14- 19 I6 --- Planet [96086/404979]? Asteroid number
22- 31 A10 --- ID MPC identifier if previously known
33- 46 F14.6 d JD [2458583.7/2459140] Julian Date
48- 54 F7.4 mag mag [18.75/25.17] Apparent AB magnitude (1)
56- 61 F6.4 mag e_mag [0.0016/0.06] Uncertainty in mag
63- 67 A5 --- Block Observation block identifier; see Table 1 (G1)
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Note (1): The g-band filter was used for the 19APR observations, and the
r2-band was used for the other three blocks.
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- FOSSIL FOSSIL survey identifier
14- 19 I6 --- Planet [96086/404979]? Asteroid number
21- 30 A10 --- ID MPC identifier if previously known
32- 36 A5 --- Block Block ID of the observation (G1)
38- 41 F4.1 mag HMag [13.5/19.3] Absolute magnitude, H, in
the observed band (g for 19Apr or r2)
43- 47 F5.2 km Diam [0.73/10.42] Diameter, D
49- 52 F4.2 km e_Diam [0.08/1.12] Diam uncertainty
54- 59 F6.3 h Per [1.633/13.521] Rotation period
61- 65 F5.3 h e_Per [0.006/2.274] Per uncertainty
67- 70 F4.2 mag Dmag [0.17/1] Lightcurve amplitude, δm
72- 75 F4.1 mag magAvg [18.9/24.7] Mean magnitude
77- 81 F5.2 --- B1 [-0.26/0.05] B1 fit parameter
83- 87 F5.2 --- C1 [-0.12/0.17] C1 fit parameter
89- 93 F5.2 --- B2 [-0.57/0.24] B2 fit parameter
95- 99 F5.2 --- C2 [-0.24/0.21] C2 fit parameter
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Global notes:
Note (G1): Details of the observations for each survey block (Table 1):
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Block RAdeg DEdeg JT Np Filt Exp Lim C Date Exp Span
ID Cl (s) mag min Pt (h)
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19Apr 197.526 -6.763 L5 5 g 90 24.5 10 2019-04-10 53 8.8
20May 224.351 -14.596 L5 2 r2 300 25.6 11 2020-05-19 23 3.8
20May 224.351 -14.596 L5 2 r2 300 25.7 11 2020-05-20 21 3.8
20Aug 341.656 -6.039 L4 3 r2 300 25.6 16 2020-08-21 16 4.5
20Aug 341.656 -6.039 L4 3 r2 300 25.6 16 2020-08-22 15 4.0
20Aug 341.656 -6.039 L4 3 r2 300 25.5 16 2020-08-23 15 4.1
20Oct 10.119 5.754 L4 3 r2 150 25.5 15 2020-10-14 24 3.4
20Oct 10.119 5.754 L4 3 r2 150 25.4 15 2020-10-15 24 3.4
20Oct 10.119 5.754 L4 3 r2 150 24.0 15 2020-10-16 8 1.0
20Oct 10.119 5.754 L4 3 r2 150 24.0 15 2020-10-17 8 1.0
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History:
From electronic version of the journal
References:
Chang et al. Paper I.: Jupiter Trojans. 2021PSJ.....2..191C 2021PSJ.....2..191C
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 24-May-2022