(26375) 1999 DE ₉

Asteroid (26375) 1999 DE 9
Properties of the orbit ( animation ) Epoch:  April 27, 2019 ( JD 2,458,600.5)
Orbit type	RKBO 2: 5 , or SDO , "Distant Object"
Major semi-axis	55,511  AU
eccentricity	0.417
Perihelion - aphelion	32,369 AU - 78,653 AU
Inclination of the orbit plane	7.6 °
Length of the ascending node	323.1 °
Argument of the periapsis	159.9 °
Time of passage of the perihelion	April 20, 1986
Sidereal period	413 a 7.1 M.
Mean orbital velocity	3.965 km / s
Physical Properties
Medium diameter	${\displaystyle 461{,}0_{-45,3}^{+46,1}\,\mathrm {km} }$
Dimensions	≈ 1.025  ·  10 20 kg
Albedo	${\displaystyle 0{,}069_{-0,012}^{+0,016}\,\mathrm {km} }$
Medium density	≈ 2.0 g / cm³
Rotation period	24 h (1.0 d )
Absolute brightness	4.70 - 5.21 mag
Spectral class	C B-V = 0.967 ± 0.043 VR = 0.579 ± 0.036 VI = 1.147 ± 0.044 BR = 1.536 ± 0.056
history
Explorer	Scott S. Sheppard Jane X. Luu Amanda S. Bosh Jan T. Kleyna Amanda A. Sickafoose
Date of discovery	February 20, 1999
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.

(26375) 1999 DE ₉ is a large trans-Neptunian object in the Kuiper belt , which is classified dynamically as a resonant Kuiper belt object (2: 5 resonance) or as a scattered disk object (SDO). Because of its size, the asteroid is a dwarf planet candidate .

discovery

1999 DE ₉ was discovered on February 20, 1999 by Scott Sheppard and Jane Luu (official) as well as Amanda Bosh, Jan Kleyna and Amanda Sickafoose with the 0.9 m telescope at the Kitt Peak Observatory ( Arizona ). The discovery was announced on July 5, 2000, the planetoid was later given the minor planet number 26375 by the IAU .

After its discovery, DE _{9 could be identified} in photos up to January 29, 1990, taken as part of the Digitized Sky Survey program, and its observation period was extended by nine years in order to calculate its orbit more precisely. In April 2017, a total of 266 observations were made over a period of 27 years. The last observation so far was carried out in April 2017 on the Pan-STARRS telescope. (As of February 28, 2019)

properties

Orbit

1999 DE ₉ orbits the sun in 413.59 years on a strongly elliptical orbit between 32.37  AU and 78.65 AU from its center. The eccentricity of the orbit is 0.417, the orbit is inclined 7.63 ° with respect to the ecliptic . Currently, the planetoid is 39.35 AU from the sun. The last time it passed through perihelion was in 1986, so the next perihelion should take place in 2400.

Marc Buie ( DES ) classifies the planetoid as RKBO ( 2: 5 resonance with Neptune ), while the Minor Planet Center classifies it as an SDO and generally as a "Distant Object".

size

A diameter of around 461 km is currently assumed, based on a reflectivity of 6.9% and an absolute brightness of 5.21  ^m , which was determined using the light curves with the Spitzer space telescope . Assuming a diameter of 461 km, this results in a total surface of around 668,000 km². The apparent brightness of 1999 DE ₉ is 20.93  ^m , the mean surface temperature is estimated at only 37  K (−236 ° C), which corresponds to the temperature of the Neptune moon Triton , the coldest directly measured temperature in the solar system to date . Based on an estimated general average density of 2 g / cm³, the mass is estimated to be 1.025  ·  10 ²⁰  kg.

Since it can be assumed that 1999 DE ₉ is in hydrostatic equilibrium due to its size and must therefore be largely round, it should meet the criteria for classification as a dwarf planet . Both Mike Brown and Gonzalo Tancredi assume that 1999 DE ₉ is possibly a dwarf planet.

Spectral light curve analyzes showed only small deviations, which indicates a round shape with no albedo spots, and traces of a few percent water ice were found on the surface. Some results also suggest the presence of the hydroxy group .

Based on light curve observations, which could only be partially carried out, 1999 DE ₉ rotates once around its axis in at least 24 hours. From this it would follow that in a 1999 DE ₉ year he performed 151064.9 self- rotations (“days”). This one day rotation period seems to represent a lower bound and is possibly completely wrong.

Determination of the diameter for 1999 DE ₉

year	Dimensions km	source
2007	461.0 + 046.1- 045.3	Stansberry et al. a.
2008	482.0	Tancredi
2010	482.0	Tancredi
2013	311.0 + 029.0- 032.0	Lellouch u. a.
2013	444.0	Mommert et al. a.
2015	383.27	LightCurve DataBase
2018	474.0	Brown
The most precise determination is marked in bold .

See also

• List of trans-Neptunian objects
• List of dwarf planets of the solar system
• List of asteroids
• List of moons from asteroids

Web links

• 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

1. ^ ^{A b} Marc W. Buie : Orbit Fit and Astrometric record for 26375 . SwRI (Space Science Department). Retrieved February 28, 2019.
2. ↑ ^{a b} E. Lellouch u. a .: “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 .
3. ^ Wm. R. Johnston: List of Known Trans-Neptunian Objects . Johnston's Archives. October 7, 2018. Retrieved February 28, 2019.
4. ↑ ^{a b} MPC : MPEC List Of Centaurs and Scattered-Disk Objects . IAU . Retrieved February 28, 2019.
5. ↑ ^{a b c d} (26375) 1999 DE9 at the IAU Minor Planet Center (English) Retrieved on February 28, 2019.
6. ↑ v ≈ π * a / period (1 + sqrt (1-e²))
7. ↑ ^{a b c} J. Stansberry et al. a .: Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope (PDF) . In: University of Arizona Press . 592, No. 161-179, February 20, 2007. arxiv : astro-ph / 0702538 . bibcode : 2008ssbn.book..161S .
8. ↑ ^{a b c} (26375) 1999 DE9 in the Small-Body Database of the Jet Propulsion Laboratory (English). Retrieved February 28, 2019.
9. ↑ ^{a b} LCDB Data for (26375) 1999DE9 . MinorPlanetInfo. 2015. Retrieved February 25, 2019.
10. ↑ ^{a b c} O. Hainaut u. a .: Colors of minor bodies in the outer solar system. II. A statistical analysis revisited (PDF) . In: Astronomy and Astrophysics . 546, No. A115, September 10, 2012, p. 20. arxiv : 1209.1896 . bibcode : 2012A & A ... 546A.115H . doi : 10.1051 / 0004-6361 / 201219566 .
11. ↑ N. Peixinho et al. a .: The bimodal colors of Centaurs and small Kuiper belt objects (PDF) . In: Astronomy and Astrophysics . 546, No. A86, June 14, 2012, p. 12. arxiv : 1206.3153 . bibcode : 2012A & A ... 546A..86P . doi : 10.1051 / 0004-6361 / 201219057 .
12. ↑ MPC : MPEC 2000-N11: 1999 DE9 . IAU . July 5, 2000. Retrieved February 28, 2019.
13. ↑ (26375) 1999 DE9 in the database of the "Asteroids - Dynamic Site" (AstDyS-2, English).
14. ↑ ^{a b} Mike Brown : How many dwarf planets are there in the outer solar system? . CalTech . November 12, 2018. Retrieved February 28, 2019.
15. ↑ ^{a b} Gonzalo Tancredi: Physical and dynamical characteristics of icy “dwarf planets” (plutoids) (PDF) . In: International Astronomical Union (Ed.): Icy Bodies of the Solar System: Proceedings IAU Symposium No. 263, 2009 . 2010. doi : 10.1017 / S1743921310001717 . Retrieved February 25, 2019.
16. ^ Gonzalo Tancredi, Sofía Favre: DPPH List . In: Dwarf Planets and Plutoid Headquarters, from Which are the dwarfs in the solar system? . August. Retrieved February 25, 2019.
17. ↑ M. Mommert et al. a .: Remnant planetesimals and their collisional fragments: Physical characterization from thermal-infrared observations . September 23, 2013. Accessed February 25, 2019.