Asteroids with Satellites Database--Johnston's Archive
(208996)
Achlys
compiled by Wm. Robert Johnston
last updated
29 September 2025
--Orbital and physical data--
(See this page for definitions of quantities; source codes in brackets, see this link for full references; *A, *D, and *E indicate assumed, derived, and estimated values, respectively.)
dynamical type, primary:
TNO, plutino
orbital data, primary (osculating elements)
[JPL]
: |
semimajor axis a: |
39.627546 AU
| |
orbital period P: |
249.46175 yr
(= 91115.906 d)
| |
eccentricity e: |
0.1748402
| |
perihelion distance q: |
32.69906 AU
| |
aphelion distance Q: |
46.556033 AU
| |
inclination i: |
13.5452432°
| |
argument of perihelion ω: |
14.40226°
| |
ascending node Ω: |
251.872934°
| |
mean anomaly M: |
242.81014°
| |
perihelion passage TP: |
2107 Feb 05.72
| |
Epoch: |
2025 Nov 21
| |
data arc: |
1996-2025
(1061 obs.)
| |
Earth MOID: |
31.6833 AU
| |
Jupiter Tisserand invariant TJ: |
5.414
|
| Neptune Tisserand invariant TN: | 2.95653163107859 [*D] |
orbital data, secondary:
|
semimajor axis as: |
7200
± 300 km
(separation)
[B07d]
| |
separation/primary radius as/rp: | 19 [*E] | |
separation/Hill radius as/rH: | 0.0046 [*E] | |
orbital period Ps: |
12
d [*E]
| |
eccentricity es: |
?
| |
normalized ang. mom. αL: |
?
|
|
other data, system (combined):
|
absolute mag. H: |
3.72
[MPC]
3.74 ± 0.08 [M12a]
| |
slope parameter G: |
(0.15) [*A]
| |
effective diameter dE: |
772
± 12
km [D17a]
| |
geometric albedo: |
0.107
± 0.023/0.016
[M12a]
| |
color index U-B: |
?
| |
color index B-V: |
0.65
[F04a]
| |
color index V-R: | 0.39 ± 0.03 [F04a] | |
color index B-R: | 1.04 ± 0.03 [F04a] | |
color index V-I: | 0.75 ± 0.03 [F04a] | |
color index R-J: | 0.82 ± 0.06 [P10a] | |
color index V-J: | 1.21 ± 0.05 [D09c] | |
color index J-H: | 0.34 ± 0.08 [P10a] | |
color index V-H: | 1.52 ± 0.05 [D09c] | |
taxonomic type: |
BB (G-mode) [P10a]
| |
mass m: |
2.02x1020
kg [*D]
| |
density ρ: |
>0.85
g/cm3[T10a]
| |
Hill radius rH: |
1600000 km [*D]
|
other data, primary:
|
diameter dp: |
768
± 64
km [*D]
| |
axial ratios a/b, b/c: | 1.1, ? [*E] | |
rotation period RPp: |
6.787
± 0
h [S17b]
| |
amplitude in mag., rotational ΔM: |
0.07
± 0.01
[T10a]
| |
pole direction Β, λ: |
?
,
?
|
other data, secondary:
|
diameter ds: |
72
± 12
km [*D]
| |
diameter ratio ds/dp: |
0.1
± 0.014
[B07d]
| |
component mag. difference ΔM: |
5.0
± 0.3
[I8812]
| |
rotation period RPs: |
?
| |
|
|
--
(208996) Achlys
--discovery and notes:
Primary discovered
2003 Jan 13
from
Palomar Observatory, California, USA
by
C. A. Trujillo and M. E. Brown.
Alternate designation(s):
2003 AZ84
.
Linked to prediscovery observations from 1996 Mar 19.
Permanent number assigned 2009 Mar 11.
Named 2025 Jun 30 for the Greek personification of sorrow and grief [WGSBN0515].
Companion discovered
2005 Dec 02
by M. E. Brown and T.-A. Suer
using
Hubble Space Telescope
observations from Hubble Space Telescope.
Announced
2007 Feb 22 [B07d].
--Links, more technical:
--Links, less technical:
--Links to ADS abstracts:
- Braga Ribas, Felipe, Sicardy, B., Ortiz, J. L., Duffard, R., Camargo, J. I. B., Lecacheux, J., Colas, F., Vachier, F., Tanga, P., Sposetti, S., Brosch, N., Kaspi, S., Manulis, I., Baug, T., Chandrasekhar, T., Ganesh, S., Jain, J., Mohan, V., Sharma, A., Garcia-Lozano, R., Klotz, A., Frappa, E., Jehin, E., Assafin, M., Vieira Martins, R., Behrend, R., Roques, F., Widemann, T., Morales, N., Thirouin, A., Mahasena, P., Benkhaldoun, Z., Daassou, A., Rinner, C., & Ofek, E. O. 2012, AAS/Division for Planetary Sciences Meeting Abstracts Stellar Occultations by Large TNOs on 2012: The February 3rd by (208996) 2003 AZ84, and the February 17th by (50000) Quaoar
- Assafin, M., Camargo, J. I. B., Vieira Martins, R., Braga-Ribas, F., Sicardy, B., Andrei, A. H., & da Silva Neto, D. N. 2012, Astronomy and Astrophysics Candidate stellar occultations by large trans-Neptunian objects up to 2015
- Braga-Ribas, F., Sicardy, B., Ortiz, J. L., Jehin, E., Camargo, J. I. B., Assafin, M., Behrend, R., Unda-Sanzana, E., Colque, J. P., Morales, N., Tancredi, G., Roland, S., Bruzzone, S., Salvo, R., Almenares, L., Emilio, M., Schoenell, W., Gil-Hutton, R., Milone, A., Jacques, C., Vanzi, L., Kavelaars, J. J., Cacella, P., Maury, A., Alvarez, E., van der Bliek, N. S., Vieira-Martins, R., Colas, F., Lecacheux, J., Vachier, F., Roques, F., Widemann, T., Thirouin, A., Gillon, M., Manfroid, J., Bergengruen, A., Martinez, M., Capeche, J., Amorim, A., Pimentel, E., Leiva, R., Toledo, I., Almeida, L. A., Magalhães, V. S., Montaña, C. E., & Rodrigues, C. V. 2011, EPSC-DPS Joint Meeting 2011 Stellar Occultations by TNOs: the January 08, 2011 by (208996) 2003 AZ84 and the May 04, 2011 by (50000) Quaoar
- Braga-Ribas, F., Sicardy, B., Colas, F., Lecacheux, J., Maury, A., Ortiz, J. L., Morales, N., de, I., Jehin, E., Manfroid, J., Gillon, M., Assafin, M., Vieira-Martins, R., Camargo, J. I. B., & Harlinten, C. 2011, Central Bureau Electronic Telegrams Stellar Occultation by Transneptunian Object (208996) 2003 AZ84
- Delsanti, A., Merlin, F., Guilbert-Lepoutre, A., Bauer, J., Yang, B., & Meech, K. J. 2010, Astronomy and Astrophysics Methane, ammonia, and their irradiation products at the surface of an intermediate-size KBO?. A portrait of Plutino (90482) Orcus
- Fornasier, S., Barucci, M. A., de Bergh, C., Alvarez-Candal, A., DeMeo, F., Merlin, F., Perna, D., Guilbert, A., Delsanti, A., Dotto, E., & Doressoundiram, A. 2009, Astronomy and Astrophysics Visible spectroscopy of the new ESO large programme on trans-Neptunian objects and Centaurs: final results
- Fornasier, S., Doressoundiram, A., Tozzi, G. P., Barucci, M. A., Boehnhardt, H., de Bergh, C., Delsanti, A., Davies, J., & Dotto, E. 2004, Astronomy and Astrophysics ESO Large Program on physical studies of Trans-Neptunian objects and Centaurs: Final results of the visible spectrophotometric observations
- de Bergh, C., Barucci, A., Doressoundiram, A., & Dotto, E. 2004, 35th COSPAR Scientific Assembly Spectroscopy of Kuiper Belt Objects and Centaurs
- Sheppard, Scott S. & Jewitt, David C. 2003, Earth Moon and Planets Hawaii Kuiper Belt Variability Project: An Update
- Helin, E. F., Pravdo, S., Lawrence, K., Thicksten, R., Haver, R., Pelloni, A., Forti, G., Chiang, E. I., Jordan, A. B., Young, J., Trujillo, C. A., & Marsden, B. G. 2003, Minor Planet Electronic Circulars 2003 AZ84
- Trujillo, C. A., Brown, M. E., Helin, E. F., Pravdo, S., Lawrence, K., Hicks, M., & Marsden, B. G. 2003, Minor Planet Electronic Circulars 2003 AZ84
©
2007-2014, 2025
by Wm. Robert Johnston.
Last modified
29 September 2025.
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