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| discovered = December 17, 2009
| discovered = December 17, 2009
| mp_name = {{mp|2009 YE|7}}
| mp_name = {{mp|2009 YE|7}}
| mp_category = [[Trans-Neptunian object|TNO]]<br>[[Scattered disc]]<ref name=jpldata/><br>[[Haumea family]]?<ref name="Brown2009">{{cite web
| mp_category = [[Trans-Neptunian object|TNO]]<br>[[Cubewano]]<ref name=jpldata/><br>[[Haumea family]]?<ref name="Brown2009">{{cite web
|date=2009-12-29
|date=2009-12-29
|title=A ghost of Christmas past
|title=A ghost of Christmas past
Line 30: Line 30:
|accessdate=2009-12-29}}</ref>
|accessdate=2009-12-29}}</ref>
| orbit_ref = <ref name="jpldata">{{cite web
| orbit_ref = <ref name="jpldata">{{cite web
|date=2010-03-21 last obs
|date=2010-09-12 last obs
|title=JPL Small-Body Database Browser: (2009 YE7)
|title=JPL Small-Body Database Browser: (2009 YE7)
|url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009YE7
|url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009YE7
|accessdate=2010-03-02}}</ref>
|accessdate=2010-09-13}}</ref>
| epoch = January 24, 2010 (2455220.5)
| epoch = July 23, 2010 (2455400.5)
| aphelion = 77.7 [[Astronomical unit|AU]] (Q)
| aphelion = 50.7 [[Astronomical unit|AU]] (Q)
| perihelion = 30.9 AU (q)
| perihelion = 38.3 AU (q)
| semimajor = 54.3 AU (a)
| semimajor = 44.5 AU (a)
| eccentricity = 0.43
| eccentricity = 0.14
| period = 400 [[Julian year (astronomy)|yr]]
| period = 297 [[Julian year (astronomy)|yr]]
| avg_speed = 3.85
| avg_speed = 4.47
| inclination = 29.1[[degree (angle)|°]]
| inclination = 29.1[[degree (angle)|°]]
| asc_node = 141°
| asc_node = 141°
| mean_anomaly = 303° (M)
| mean_anomaly = 177° (M)
| arg_peri = 21.8°
| arg_peri = 97.3°
| satellites = ?
| satellites = ?
| physical_characteristics = yes
| physical_characteristics = yes
Line 64: Line 64:
| spectral_type =
| spectral_type =
| magnitude = ~21.7<sup>(JPL Horizons)</sup>
| magnitude = ~21.7<sup>(JPL Horizons)</sup>
| abs_magnitude = 4.4<ref name="jpldata"/>
| abs_magnitude = 4.5<ref name="jpldata"/>
}}
}}


'''{{mp|2009 YE|7}}''' is a [[trans-Neptunian object]] with an [[Absolute magnitude#Solar System bodies (H)|absolute magnitude]] (H) of 4.4.<ref name="jpldata"/> Though it only qualifies as a weak [[List of dwarf planet candidates|dwarf planet candidate]] since it is also suspected of being a highly reflective icy member of the [[Haumea family]].<ref name="Brown2009"/> It was discovered by [[David Rabinowitz]] on December 17, 2009 at the [[La Silla Observatory]] in Chile. When {{mp|2009 YE|7}} was first discovered it was believed to have an absolute magnitude (H) of 2.8, which would have made it the first bright KBO found from the southern hemisphere.<ref name=jpl-count>{{cite web
'''{{mp|2009 YE|7}}''' is a [[trans-Neptunian object]] with an [[Absolute magnitude#Solar System bodies (H)|absolute magnitude]] (H) of 4.5.<ref name="jpldata"/> Though it only qualifies as a weak [[List of dwarf planet candidates|dwarf planet candidate]] since it is also suspected of being a highly reflective icy member of the [[Haumea family]].<ref name="Brown2009"/> It was discovered by [[David Rabinowitz]] on December 17, 2009 at the [[La Silla Observatory]] in Chile. When {{mp|2009 YE|7}} was first discovered it was believed to have an absolute magnitude (H) of 2.8, which would have made it the first bright KBO found from the southern hemisphere.<ref name=jpl-count>{{cite web
|date=2009-12-27
|date=2009-12-27
|title=JPL Small-Body Database Search Engine (H<=4)
|title=JPL Small-Body Database Search Engine (H<=4)
Line 81: Line 81:
===Absolute magnitude===
===Absolute magnitude===
[[File:Planet-albedo20vs70.gif|160px|thumb|left|Different albedos will result in different sizes]]
[[File:Planet-albedo20vs70.gif|160px|thumb|left|Different albedos will result in different sizes]]
The size of an object can be ascertained once its [[Absolute magnitude#Solar System bodies (H)|absolute magnitude]] (H) and its [[albedo]] (the proportion of light it reflects) are known. {{mp|2009 YE|7}} has an absolute magnitude (H) of 4.4.<ref name="jpldata"/> Since {{mp|2009 YE|7}} has an absolute magnitude dimmer than (H=1), it will not be overseen by two naming committees and will not ''automatically'' be listed as a dwarf planet by the [[International Astronomical Union]] (IAU).<ref name=iau2008>{{cite press release
The size of an object can be ascertained once its [[Absolute magnitude#Solar System bodies (H)|absolute magnitude]] (H) and its [[albedo]] (the proportion of light it reflects) are known. {{mp|2009 YE|7}} has an absolute magnitude (H) of 4.5.<ref name="jpldata"/> Since {{mp|2009 YE|7}} has an absolute magnitude dimmer than (H=1), it will not be overseen by two naming committees and will not ''automatically'' be listed as a dwarf planet by the [[International Astronomical Union]] (IAU).<ref name=iau2008>{{cite press release
|url=http://www.iau.org/public_press/news/release/iau0804/
|url=http://www.iau.org/public_press/news/release/iau0804/
|title=Plutoid chosen as name for Solar System objects like Pluto}}</ref>
|title=Plutoid chosen as name for Solar System objects like Pluto}}</ref>

Revision as of 19:31, 13 September 2010


2009 YE7
Discovery[1]
Discovered byDavid Rabinowitz
Discovery dateDecember 17, 2009
Designations
Designation
2009 YE7
TNO
Cubewano[2]
Haumea family?[3]
Orbital characteristics[2]
Epoch July 23, 2010 (2455400.5)
Aphelion50.7 AU (Q)
Perihelion38.3 AU (q)
44.5 AU (a)
Eccentricity0.14
297 yr
4.47
177° (M)
Inclination29.1°
141°
97.3°
Known satellites?
Physical characteristics
Dimensions210[4]–584[5] km[2][6]
Albedoassume 0.7 to 0.09
~21.7(JPL Horizons)
4.5[2]

2009 YE7 is a trans-Neptunian object with an absolute magnitude (H) of 4.5.[2] Though it only qualifies as a weak dwarf planet candidate since it is also suspected of being a highly reflective icy member of the Haumea family.[3] It was discovered by David Rabinowitz on December 17, 2009 at the La Silla Observatory in Chile. When 2009 YE7 was first discovered it was believed to have an absolute magnitude (H) of 2.8, which would have made it the first bright KBO found from the southern hemisphere.[7]

Orbit

The preliminary orbit suggests it will come to perihelion around 2073,[2] and is currently about 50 AU from the Sun.

The orbit is preliminary as it has only been observed over an observation-arc of 98 days since December 13, 2009.[2]

Physical characteristics

Absolute magnitude

Different albedos will result in different sizes

The size of an object can be ascertained once its absolute magnitude (H) and its albedo (the proportion of light it reflects) are known. 2009 YE7 has an absolute magnitude (H) of 4.5.[2] Since 2009 YE7 has an absolute magnitude dimmer than (H=1), it will not be overseen by two naming committees and will not automatically be listed as a dwarf planet by the International Astronomical Union (IAU).[8]

EarthMoonCharonCharonNixNixKerberosKerberosStyxStyxHydraHydraPlutoPlutoDysnomiaDysnomiaErisErisNamakaNamakaHi'iakaHi'iakaHaumeaHaumeaMakemakeMakemakeMK2MK2XiangliuXiangliuGonggongGonggongWeywotWeywotQuaoarQuaoarSednaSednaVanthVanthOrcusOrcusActaeaActaeaSalaciaSalacia2002 MS42002 MS4File:10 Largest Trans-Neptunian objects (TNOS).png
Artistic comparison of Pluto, Eris, Makemake, Haumea, Gonggong (2007 OR10), Sedna, Quaoar, Orcus, 2002 MS4, and Salacia.

Assuming 2009 YE7 has a trans-Neptunian albedo of about 0.25, which is somewhat common with KBOs around a size of ~1000km, it would only be around 350 km in diameter.[6] But since the true albedo is unknown, it could easily be from about 210 to an unlikely 584 km in diameter.

Mike Brown believes that 2009 YE7 may be a Haumea family fragment due to the Haumea-like inclination of the orbit.[3] If this is the case, 2009 YE7 could have an albedo of up to 0.7, resulting in a smaller size closer to the 220km estimate. If infrared spectrums show that 2009 YE7 has evidence of deep water ice absorption features, it would link 2009 YE7 to the Haumea family.[3]

Any icy body with a diameter greater than 400 km is likely spherical.[9] Many small icy low-density moons are known to be spherical.

See also

References

  1. ^ "List of Transneptunian Objects". IAU Minor Planet Center. 2009-12-28. Retrieved 2009-12-28.
  2. ^ a b c d e f g h "JPL Small-Body Database Browser: (2009 YE7)". 2010-09-12 last obs. Retrieved 2010-09-13. {{cite web}}: Check date values in: |date= (help)
  3. ^ a b c d Mike Brown (2009-12-29). "A ghost of Christmas past". Mike Brown's Planets (blog). Retrieved 2009-12-29.
  4. ^ Assuming a Haumea-like albedo of 0.7
  5. ^ Assuming an unlikely albedo of 0.09
  6. ^ a b Dan Bruton. "Conversion of Absolute Magnitude to Diameter for Minor Planets". Department of Physics & Astronomy (Stephen F. Austin State University). Retrieved 2009-01-07.
  7. ^ "JPL Small-Body Database Search Engine (H<=4)". 2009-12-27. Retrieved 2009-12-27.
  8. ^ "Plutoid chosen as name for Solar System objects like Pluto" (Press release).
  9. ^ Mike Brown. "The Dwarf Planets". Retrieved 2009-12-28.
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