(174567) Varda

Asteroid (174567) Varda
Properties of the orbit ( animation ) Epoch: April 27, 2019 ( JD 2,458,600.5)
Orbit type	DO (E SDO ) or Cubewano ( «Heiss» ), «Distant Object»
Major semi-axis	46.116 AU
eccentricity	0.142
Perihelion - aphelion	39.589 AU - 52.643 AU
Inclination of the orbit plane	21.5 °
Length of the ascending node	184.1 °
Argument of the periapsis	180.1 °
Time of passage of the perihelion	April 1, 2094
Sidereal period	313 a 2 M
Mean orbital velocity	4,350 km / s
Physical Properties
Medium diameter	${\ displaystyle 716 {,} 6 _ {- 4.8} ^ {+ 4.8} \, \ mathrm {km}}$
Dimensions	2.65 ± 0.03  ·  10 ²⁰ kg
Albedo	0.102 ± 0.024
Medium density	${\ displaystyle 1 {,} 24 _ {- 0.35} ^ {+ 0.50} \ mathrm {}}$ g / cm³
Rotation period	5.91 ± 0.06 h (0.246) d
Absolute brightness	3.097 - 3.930 mag
Spectral class	C B-V = 0.886 ± 0.025 VR = 0.540 ± 0.030 V-I = 1.156 ± 0.029 BR = 1.450 ± 0.040
history
Explorer	Jeffrey A. Larsen
Date of discovery	June 21, 2003
Another name	2003 MW ₁₂
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.

(174567) Varda (former designation 2003 MW ₁₂ ) is a large trans-Neptunian object in the Kuiper belt , which is classified as an extended Scattered Disk Object (DO) or as a Cubewano in terms of orbital dynamics . Due to its size of around 717 km, it is a dwarf planet candidate . Varda has a natural companion named Ilmarë , which is just under half the diameter of the asteroid . Since both revolve around the common center of gravity , the system can also be understood as a double asteroid system.

Discovery and naming

Varda was discovered on June 21, 2003 by Jeffrey A. Larsen with the 0.9 m Spacewatch telescope at the Steward Observatory of the Kitt Peak Observatory as part of a project of the United States Naval Academy . The discovery was announced on January 7, 2006; the planetoid was initially given the provisional designation 2003 MW ₁₂ and later the minor planet number 174567 from the IAU .

Varda was named on January 16, 2014 after the star queen Varda Elentári from J. R. R. Tolkien's Silmarillion .

After her discovery, Varda could be identified in photos up to March 19, 1980, which were taken as part of the Sloan Digital Sky Survey (SDSS) at the Siding Spring Observatory , and so her orbit was calculated more precisely. Since then, the planetoid has been observed through various telescopes such as the Hubble , Herschel, and Spitzer Space Telescopes, as well as various earth-based telescopes. In April 2017, a total of 216 observations were made over a period of 36 years. The last observation so far was made in July 2018 at the Purple Mountain Observatory . (As of March 25, 2019)

properties

The orbit of Varda (white) compared to Pluto and the planets.

Orbit

Varda orbits the Sun in an elliptical orbit between 39.59 AU and 52.64 AU from its center within 313.18 years . The eccentricity of the orbit is 0.142, the orbit is inclined at 21.50 ° to the ecliptic . The planetoid is currently 46.63 AU from the Sun and 47.16 AU from Earth . The perihelion it passes the next time in 2094, the last Periheldurchlauf should be done so in the 1781st

Marc Buie ( DES ) classifies the planetoid as an extended SDO (ESDO or DO a), while the Minor Planet Center him as Cubewano classifies, and he to the ground dynamically "hot" classical KBO would belong; the latter also lists it as a non-SDO and generally as a “distant object” .

Size and rotation

Investigations in 2013 with the Herschel space telescope (instruments SPIRE and PACS) combined with the revised data from the Spitzer space telescope (instrument MIPS) came to the conclusion in 2014 that the diameter of Varda is about 705 km, that of Ilmarë about 361 km. A star occultation on September 10, 2018 determined the diameter of Varda to be 716.6 km. Based on a diameter of 716.6 km, the total area is about 1,613,000 km², which roughly corresponds to the area of Iran including Armenia . The apparent magnitude of Varda is 20.33 ^m .

Since it can be assumed that Varda is in hydrostatic equilibrium due to its size and should therefore be largely round, it should meet the criteria for classification as a dwarf planet . Mike Brown believes that Varda is most likely a dwarf planet. According to Gonzalo Tancredi, it is only possibly one.

Using light curve observations , Varda rotates once around its axis in 5 hours and 54.6 minutes. From this it follows that in a Varda year it performs 464518.8 self- rotations ("days"). However, this is still fraught with uncertainties, as the observation time at that time was insufficient and the error rate is around 30%.

Provisions of the diameter for Varda
year	Dimensions km	source
2008	730.0	Tancredi
2010	801.0	Tancredi
2013	592.0 ^+91.0_−84.0	Lellouch u. a.
2014	792.0 ^+91.0_−84.0(System) 705.0 ^+81.0_-75.0	Vilenius et al. a.
2014	<412.0 (system) <366.0	Thirouin et al. a.
2015	722.0 ^+82.0_-76.0	Grundy et al. a.
2013	878.06	LightCurve DataBase
2018	716.6 ± 4.8	Anderson et al. a.
2018	689.0	Brown
The most precise determination is marked in bold .

internal structure

By analyzing the orbit of the moon Ilmarë, the mass of the system could be determined to be 2.65  ·  10 ²⁰ kg. With diameters of around 717 km and 361 km, the result is a density of 1.25 ± 0.40 g / cm³ - hardly higher than that of water. The surfaces of Varda and Ilmarë appear reddish in the visible spectrum and in the near infrared . The spectrum shows no absorption lines from water ice , but from methanol ice .

moon

In 2011, a team of astronomers led by Keith S. Noll announced the discovery of a companion named Ilmarë , 326 km in diameter, and tracked down using images from the Hubble Space Telescope . It circles the common barycentre with Varda in 5 days and 18 hours at a mean distance of 4809 ± 400 km. One orbit of Ilmarë takes 23.35 Varda days. The system mass was determined to be 2.664 ± 0.064  ·  10 ²⁰ . Since both circle around the common barycentre and are of comparable size, the system can be understood as a double asteroid system. It was named after Varda's maid in the Silmarillion.

The Varda 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 Varda's equator	Date of discovery Date of publication
(174567) Varda	716.6	100.00	2.66  ·  10 ²⁰	-	-	-	-	June 21, 2003 January 7, 2006 50060107 ♠0
Ilmarë (Varda I)	326.0	45.49	?	4809	5.75058	0.0215	21.2 °	April 26, 2009 50110000 ♠2011

Web links

Varda pre-discovery photos
How many dwarf planets are there in the outer solar system? Current list of the largest TNOs from Mike Brown
Free the dwarf planets! Mike Brown's column on the IAU and the dwarf planets regarding their classifications (23 August 2011)

Individual evidence

^ ^A ^b Marc W. Buie : Orbit Fit and Astrometric record for 174567 . SwRI (Space Science Department). Retrieved March 25, 2019.
↑ ^a ^b MPC : MPEC 2010-S44: Distant Minor Planets (2010 OCT.11.0 TT) . IAU . September 25, 2010. Accessed March 4, 2019.
^ Wm. R. Johnston: List of Known Trans-Neptunian Objects . Johnston's Archives. October 7, 2018. Retrieved March 25, 2019.
↑ ^a ^b ^c (174567) Varda at the IAU Minor Planet Center (English) Retrieved March 25, 2019.
↑ v ≈ π * a / period (1 + sqrt (1-e²))
↑ ^a ^b ^c ^d ^e E. Vilenius u. a .: “TNOs are cool”: A survey of the trans-Neptunian region X. Analysis of classical Kuiper belt objects from Herschel and Spitzer observations (PDF) . In: Astronomy and Astrophysics . 564, No. A35, March 25, 2014, p. 18. arxiv : 1403.6309 . doi : 10.1051 / 0004-6361 / 201322416 .
↑ ^a ^b A. Thirouin et al.: Rotational properties of the binary and non-binary populations in the trans-Neptunian belt . In: Astronomy and Astrophysics . 569, September 8, 2014, p. A3. arxiv : 1407.1214 . bibcode : 2014A & A ... 569A ... 3T . doi : 10.1051 / 0004-6361 / 201423567 .
↑ ^a ^b ^c ^d ^e W. Grundy et al: The mutual orbit, mass, and density of the large transneptunian binary system Varda and Ilmarë (PDF) . In: Icarus . 257, May 4, 2015, pp. 130-138. arxiv : 1505.00510 . bibcode : 2015Icar..257..130G . doi : 10.1016 / j.icarus.2015.04.036 .
↑ H. Boehnhardt include: Photometry of Transneptunian Objects for the Herschel Key Program "TNOs are Cool" . In: Earth, Moon, and Planets . 114, No. 1-2, November 2014, pp. 35-57. bibcode : 2014EM & P..114 ... 35B . doi : 10.1007 / s11038-014-9450-x .
↑ ^a ^b LCDB Data for (174567) Varda . MinorPlanetInfo. December 2016. Retrieved March 25, 2019.
↑ ^a ^b W. Grundy: Varda and Ilmarë (174567 2003 MW12) . Lowell Observatory . Retrieved March 25, 2019.
↑ S. Tegler u. a .: Two Color Populations of Kuiper Belt and Centaur Objects and the Smaller Orbital Inclinations of Red Centaur Objects (PDF) . In: The Astronomical Journal . 152, No. 6, December 2016, p. 210, 13. bibcode : 2016AJ .... 152..210T . doi : 10.3847 / 0004-6256 / 152/6/210 .
↑ Jeffrey A. Larsen, Eric A. Roe, C. Elise Albert: The Search for Distant Objects in the Solar System Using Spacewatch . In: The Astronomical Journal . 133, No. 4, February 20, 2007, pp. 1247-1270. bibcode : 2007AJ .... 133.1247L . doi : 10.1086 / 511155 .
↑ MPC : MPEC 2006-A28: 2003 MW12 . IAU . January 7, 2006. Retrieved March 25, 2019.
↑ (174567) Varda in the Small-Body Database of the Jet Propulsion Laboratory (English). Retrieved March 25, 2019.
↑ MPC : MPEC List Of Centaurs and Scattered-Disk Objects . IAU . Retrieved March 25, 2019.
↑ ^a ^b C. Anderson et al. a .: (174567) Varda 2018 Sep 10 . Wayback machine. September 10, 2018. Retrieved March 25, 2019.
↑ (174567) Varda in the database of the "Asteroids - Dynamic Site" (AstDyS-2, English).
↑ ^a ^b Gonzalo Tancredi: Physical and dynamical characteristics of icy “dwarf planets” (plutoids) (PDF) . In: IAU (Ed.): Icy Bodies of the Solar System: Proceedings IAU Symposium No. 263, 2009 . 2010. doi : 10.1017 / S1743921310001717 . Retrieved March 25, 2019.
^ Gonzalo Tancredi, Sofía Favre: DPPH List . In: Dwarf Planets and Plutoid Headquarters, from Which are the dwarfs in the solar system? . August. Retrieved March 25, 2019.
^ E. Lellouch et al.: “TNOs are Cool”: A survey of the trans-Neptunian region. IX. Thermal properties of Kuiper belt objects and Centaurs from combined Herschel and Spitzer observations (PDF) . In: Astronomy and Astrophysics . 557, No. A60, June 10, 2013, p. 19. bibcode : 2013A & A ... 557A..60L . doi : 10.1051 / 0004-6361 / 201322047 .
↑ Mike Brown : How many dwarf planets are there in the outer solar system? . CalTech . November 12, 2018. Retrieved March 25, 2019.
^ Wm. R. Johnston: Asteroids with Satellites - (174567) Varda and IImare . Johnston's Archives. January 31, 2015. Accessed March 25, 2019.

[Buie-1] A ^b Marc W. Buie : Orbit Fit and Astrometric record for 174567 . SwRI (Space Science Department). Retrieved March 25, 2019.

[Mpc2010list-2] MPC : MPEC 2010-S44: Distant Minor Planets (2010 OCT.11.0 TT) . IAU . September 25, 2010. Accessed March 4, 2019.

[johnstonlist-3] Wm. R. Johnston: List of Known Trans-Neptunian Objects . Johnston's Archives. October 7, 2018. Retrieved March 25, 2019.

[MPC-4] (174567) Varda at the IAU Minor Planet Center (English) Retrieved March 25, 2019.

[MittOrbGesch-5] v ≈ π * a / period (1 + sqrt (1-e²))

[TNOsCool10-6] E. Vilenius u. a .: “TNOs are cool”: A survey of the trans-Neptunian region X. Analysis of classical Kuiper belt objects from Herschel and Spitzer observations (PDF) . In: Astronomy and Astrophysics . 564, No. A35, March 25, 2014, p. 18. arxiv : 1403.6309 . doi : 10.1051 / 0004-6361 / 201322416 .

[Thirouin2014-7] A. Thirouin et al.: Rotational properties of the binary and non-binary populations in the trans-Neptunian belt . In: Astronomy and Astrophysics . 569, September 8, 2014, p. A3. arxiv : 1407.1214 . bibcode : 2014A & A ... 569A ... 3T . doi : 10.1051 / 0004-6361 / 201423567 .

[Grundy2015-8] W. Grundy et al: The mutual orbit, mass, and density of the large transneptunian binary system Varda and Ilmarë (PDF) . In: Icarus . 257, May 4, 2015, pp. 130-138. arxiv : 1505.00510 . bibcode : 2015Icar..257..130G . doi : 10.1016 / j.icarus.2015.04.036 .

[Boehnhardt2014-9] H. Boehnhardt include: Photometry of Transneptunian Objects for the Herschel Key Program "TNOs are Cool" . In: Earth, Moon, and Planets . 114, No. 1-2, November 2014, pp. 35-57. bibcode : 2014EM & P..114 ... 35B . doi : 10.1007 / s11038-014-9450-x .

[lcdb-10] LCDB Data for (174567) Varda . MinorPlanetInfo. December 2016. Retrieved March 25, 2019.

[GrundyVardaIlmare-11] W. Grundy: Varda and Ilmarë (174567 2003 MW12) . Lowell Observatory . Retrieved March 25, 2019.

[Tegler2016-12] S. Tegler u. a .: Two Color Populations of Kuiper Belt and Centaur Objects and the Smaller Orbital Inclinations of Red Centaur Objects (PDF) . In: The Astronomical Journal . 152, No. 6, December 2016, p. 210, 13. bibcode : 2016AJ .... 152..210T . doi : 10.3847 / 0004-6256 / 152/6/210 .

[Larsen2007-13] Jeffrey A. Larsen, Eric A. Roe, C. Elise Albert: The Search for Distant Objects in the Solar System Using Spacewatch . In: The Astronomical Journal . 133, No. 4, February 20, 2007, pp. 1247-1270. bibcode : 2007AJ .... 133.1247L . doi : 10.1086 / 511155 .

[Mpec2006A28-14] MPC : MPEC 2006-A28: 2003 MW12 . IAU . January 7, 2006. Retrieved March 25, 2019.

[jpl-15] (174567) Varda in the Small-Body Database of the Jet Propulsion Laboratory (English). Retrieved March 25, 2019.

[MpecSDOlist-16] MPC : MPEC List Of Centaurs and Scattered-Disk Objects . IAU . Retrieved March 25, 2019.

[Anderson2018-17] C. Anderson et al. a .: (174567) Varda 2018 Sep 10 . Wayback machine. September 10, 2018. Retrieved March 25, 2019.

[AstDys-18] (174567) Varda in the database of the "Asteroids - Dynamic Site" (AstDyS-2, English).

[Tancredi2010-19] Gonzalo Tancredi: Physical and dynamical characteristics of icy “dwarf planets” (plutoids) (PDF) . In: IAU (Ed.): Icy Bodies of the Solar System: Proceedings IAU Symposium No. 263, 2009 . 2010. doi : 10.1017 / S1743921310001717 . Retrieved March 25, 2019.

[Tancredilist-20] Gonzalo Tancredi, Sofía Favre: DPPH List . In: Dwarf Planets and Plutoid Headquarters, from Which are the dwarfs in the solar system? . August. Retrieved March 25, 2019.

[TNOsCool9-21] E. Lellouch et al.: “TNOs are Cool”: A survey of the trans-Neptunian region. IX. Thermal properties of Kuiper belt objects and Centaurs from combined Herschel and Spitzer observations (PDF) . In: Astronomy and Astrophysics . 557, No. A60, June 10, 2013, p. 19. bibcode : 2013A & A ... 557A..60L . doi : 10.1051 / 0004-6361 / 201322047 .

[brownlist-22] Mike Brown : How many dwarf planets are there in the outer solar system? . CalTech . November 12, 2018. Retrieved March 25, 2019.

[johnston174567-23] Wm. R. Johnston: Asteroids with Satellites - (174567) Varda and IImare . Johnston's Archives. January 31, 2015. Accessed March 25, 2019.