(148780) Altjira

Asteroid (148780) Altjira
Properties of the orbit ( animation ) Epoch: April 27, 2019 ( JD 2,458,600.5)
Orbit type	Cubewano
Major semi-axis	44,013 AU
eccentricity	0.066
Perihelion - aphelion	41.114 AU - 46.913 AU
Inclination of the orbit plane	5.2 °
Length of the ascending node	1.8 °
Argument of the periapsis	296.3 °
Time of passage of the perihelion	April 11, 1914
Sidereal period	292 a 0 M
Mean orbital velocity	4.482 km / s
Physical Properties
Medium diameter	${\ displaystyle 246 _ {- 139} ^ {+ 38} \ mathrm {km}}$
Dimensions	3.986 ± 0.067  ·  10 ¹⁸ (system) kg
Albedo	${\ displaystyle 0 {,} 043 _ {- 0.010} ^ {+ 0.182} \ mathrm {}}$
Medium density	${\ displaystyle 0 {,} 30 _ {- 0.14} ^ {+ 0.50} \ mathrm {}}$ g / cm³
Absolute brightness	5.7 likes
history
Explorer	Deep Ecliptic Survey
Date of discovery	October 20, 2001
Another name	2001 UQ ₁₈
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . The affiliation to an asteroid family is automatically determined from the AstDyS-2 database . Please also note the note on asteroid items.

(148780) Altjira is a Trans-Neptunian object in the Kuiper Belt , which is classified as Cubewano . The asteroid has a diameter of 150 miles. Together with its moon (148780) Altjira 1 , which is slightly smaller than Altjira with a diameter of about 221 km, Altjira forms a double asteroid system .

Discovery and naming

Altjira was on 20 October 2001 by a team of astronomers in the project Deep Ecliptic Survey from the Kitt Peak National Observatory in Arizona ( USA discovered) from. The discovery was announced on November 2, 2001; the asteroid was given the preliminary designation 2001 UQ ₁₈ . On February 2, 2007 he received the minor planet number 148780 from the IAU .

On July 18, 2008, the object was named Altjira, after the Aboriginal deity of creation . According to the mythology of the Arrernte tribe in central Australia , Altjira created the earth during the dreamtime and then withdrew to heaven.

Since its discovery, the asteroid has been observed through various telescopes such as the Hubble , Herschel, and Spitzer Space Telescopes, as well as Earth-based telescopes. In September 2017 there were a total of 70 observations over a period of 7 years.

properties

Orbit

Altjira orbits the sun in a slightly elliptical orbit between 41.11 AU and 46.91 AU from its center. The eccentricity of the orbit is 0.066, the orbit is inclined at 5.2 ° to the ecliptic .

The orbital period of Altjira is 292.00 years. This is comparable to the orbital period of Quaoar (288.8 years) or Haumea (284.8 years). On its orbit around the sun Altjira orbits together with its companion (148780) Altjira 1 the common barycenter .

The rotation period is currently undefined. A double-bound rotation can be ruled out due to the long orbit of the moon.

size

The single body diameter (effective system diameter) is currently set to 331 ^{+ 051}₋₁₈₇ km estimated. Due to the dual nature of the Altjira system, the actual mean diameter of Altjira itself is 246 ^{+ 038}₋₁₃₉ km estimated; it is only 10.1% larger than its companion (148780) Altjira 1 . Altjira can be compared to the size of the asteroid (3) Juno .

Assuming a mean diameter of 246 km, this results in a surface area of around 190,100 km², which is slightly less than the area of Senegal .

Altjira's flat light curve (Δmag <0.10) indicates a relatively round shape with a homogeneous surface.

Provisions of the diameter for Altjira
year	Dimensions km	source
2008	<200.0	Brucker et al. a.
2011	220.6 (system) 164.0 ± 36	Grundy et al. a.
2012	313.0 ^{+ 050.0}_{- 048.0}(System) 257.0 ^{+ 090.0}_{- 092.0}(System) 191.1	Vilenius et al. a.
2014	331.0 ^{+ 051.0}_−187.0(System) 246.0 ^{+ 038.0}_−139.0	Vilenius et al. a.
2018	264.0	Brown
The most precise determination is marked in bold .

internal structure

Like most trans-Neptunian objects, Altjira has a low reflectance of 0.043 . The surface color is therefore darker than coal. The extremely low mean density of 0.3 g / cm³ - which is far below the density of water - is an indication that it is not a compact body, but that the asteroid is likely to be a rubble pile , a collection of Dust and rocks that are riddled with cavities.

moon

On March 17, 2007, the discovery of a great companion around Altjira was announced. The discovery is based on images taken by the Hubble Space Telescope . The moon, designated S / 2007 (148780) 1 , has a diameter of 221 kilometers and orbits the common barycentre in almost 140 days within Altjira's Hill radius (550,000 km) at a wide distance of about 9,900 km.

The Altjira system at a glance:

Components	Physical parameters			Path parameters				discovery
Surname	Throughput diameter (km)	Relative size %	Mass (kg)	Major semi-axis (km)	Orbital time (d)	eccentricity	Inclination to the ecliptic	Date of discovery Date of publication
(148780) Altjira	246.0	100.0	?	-	-	-	-	October 20, 2001 50010000 ♠2001
(148780) Altjira 1 (Altjira I)	221.0	89.9	?	9904	139.561	0.3445	35.19	August 6, 2006 50070314 ♠March 14, 2007

Web links

Wm. Robert Johnston: (148780) Altjira (English)

Individual evidence

↑ v ≈ π * a / period (1 + sqrt (1-e²))
↑ ^a ^b E. Vilenius, C. Kiss, T. Müller, M. Mommert, P. Santos-Sanz, A. Pál, J. Stansberry, M. Mueller, N. Peixinho, E. Lellouch, S. Fornasier, A Delsanti, A. Thirouin, JL Ortiz, R. Duffard, D. Perna, F. Henry: “TNOs are Cool”: A survey of the trans-Neptunian region X. Analysis of classical Kuiper belt objects from Herschel and Spitzer observations . In: Astronomy & Astrophysics . 564, January 1, 2014, p. A35. arxiv : 1403.6309 . bibcode : 2012A & A ... 541A..94V . doi : 10.1051 / 0004-6361 / 201322416 . Retrieved January 14, 2018.
↑ sphinx.planetwaves.net: Altjira. Retrieved September 20, 2017 .
↑ (148780) Altjira in the Small-Body Database of the Jet Propulsion Laboratory (English). Retrieved January 14, 2018.
↑ (148780) Altjira at the IAU Minor Planet Center (English)
↑ R. Duffard, JL Ortiz, A. Thirouin, P. Santos-Sanz, N. Morales: Transneptunian objects and Centaurs from light curves . In: Astronomy and Astrophysics . 505, No. 3, August 27, 2009, pp. 1283-1295. arxiv : 0910.1472 . bibcode : 2009A & A ... 505.1283D . doi : 10.1051 / 0004-6361 / 200912601 . Retrieved January 15, 2018.
↑ M. Brucker et al. a .: High Albedos of Low Inclination Classical Kuiper Belt Objects (December 2008)
↑ WM Grundy, KS Noll, F. Nimmo, HG Roe, MW Buie, SB Porter, SD Benecchi, DC Stephens, HF Levison, JA Stansberry: Five new and three improved mutual orbits of transneptunian binaries . In: Icarus . 213, No. 2, June 2011, pp. 678-692. arxiv : 1103.2751 . bibcode : 2011Icar..213..678G . doi : 10.1016 / j.icarus.2011.03.012 . Retrieved January 15, 2018.
↑ E. Vilenius, C. Kiss, M. Mommert, T. Müller, P. Santos-Sanz, A. Pal, J. Stansberry, M. Mueller, N. Peixinho, S. Fornasier, E. Lellouch, A. Delsanti , A. Thirouin, JL Ortiz, R. Duffard, D. Perna, N. Szalai, S. Protopapa, F. Henry, D. Hestroffer et al .: “TNOs are Cool”: A survey of the trans-Neptunian region. VI. Herschel / PACS observations and thermal modeling of 19 classical Kuiper belt objects . In: Astronomy and Astrophysics . 541, No. A94, May 4, 2012, p. 17. arxiv : 1204.0697 . bibcode : 2012A & A ... 541A..94V . doi : 10.1051 / 0004-6361 / 201118743 . Retrieved January 14, 2018.
↑ M. Brown : How many dwarf planets are there in the outer solar system? (November 2018)

[MittOrbGesch-1] v ≈ π * a / period (1 + sqrt (1-e²))

[TNOsCool10-2] E. Vilenius, C. Kiss, T. Müller, M. Mommert, P. Santos-Sanz, A. Pál, J. Stansberry, M. Mueller, N. Peixinho, E. Lellouch, S. Fornasier, A Delsanti, A. Thirouin, JL Ortiz, R. Duffard, D. Perna, F. Henry: “TNOs are Cool”: A survey of the trans-Neptunian region X. Analysis of classical Kuiper belt objects from Herschel and Spitzer observations . In: Astronomy & Astrophysics . 564, January 1, 2014, p. A35. arxiv : 1403.6309 . bibcode : 2012A & A ... 541A..94V . doi : 10.1051 / 0004-6361 / 201322416 . Retrieved January 14, 2018.

[jacobson-3] sphinx.planetwaves.net: Altjira. Retrieved September 20, 2017 .

[jpl-4] (148780) Altjira in the Small-Body Database of the Jet Propulsion Laboratory (English). Retrieved January 14, 2018.

[MPC-5] (148780) Altjira at the IAU Minor Planet Center (English)

[duffard2009-6] R. Duffard, JL Ortiz, A. Thirouin, P. Santos-Sanz, N. Morales: Transneptunian objects and Centaurs from light curves . In: Astronomy and Astrophysics . 505, No. 3, August 27, 2009, pp. 1283-1295. arxiv : 0910.1472 . bibcode : 2009A & A ... 505.1283D . doi : 10.1051 / 0004-6361 / 200912601 . Retrieved January 15, 2018.

[7] M. Brucker et al. a .: High Albedos of Low Inclination Classical Kuiper Belt Objects (December 2008)

[grundy2011-8] WM Grundy, KS Noll, F. Nimmo, HG Roe, MW Buie, SB Porter, SD Benecchi, DC Stephens, HF Levison, JA Stansberry: Five new and three improved mutual orbits of transneptunian binaries . In: Icarus . 213, No. 2, June 2011, pp. 678-692. arxiv : 1103.2751 . bibcode : 2011Icar..213..678G . doi : 10.1016 / j.icarus.2011.03.012 . Retrieved January 15, 2018.

[TNOsCool6-9] E. Vilenius, C. Kiss, M. Mommert, T. Müller, P. Santos-Sanz, A. Pal, J. Stansberry, M. Mueller, N. Peixinho, S. Fornasier, E. Lellouch, A. Delsanti , A. Thirouin, JL Ortiz, R. Duffard, D. Perna, N. Szalai, S. Protopapa, F. Henry, D. Hestroffer et al .: “TNOs are Cool”: A survey of the trans-Neptunian region. VI. Herschel / PACS observations and thermal modeling of 19 classical Kuiper belt objects . In: Astronomy and Astrophysics . 541, No. A94, May 4, 2012, p. 17. arxiv : 1204.0697 . bibcode : 2012A & A ... 541A..94V . doi : 10.1051 / 0004-6361 / 201118743 . Retrieved January 14, 2018.

[10] M. Brown : How many dwarf planets are there in the outer solar system? (November 2018)