Hiʻiaka (moon)

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Hiʻiaka
Haumea Hubble.png
In this photo taken by the Hubble Space Telescope, Hiʻiaka is the object near the top-right, above Haumea (center).
Discovery
Discovered by Michael E. Brown,
Chad Trujillo,
David Rabinowitz, et al.
Discovery date26 January 2005
Designations
Designation
Haumea I
Pronunciation /hʔiˈɑːkə/
Hawaiian:  [ˈhiʔiˈjɐkə]
(136108) 2003 EL61 I
S/2005 (2003 EL61) 1
Orbital characteristics [1]
49880±198  km
Eccentricity 0.0513±0.0078
49.12±0.03 d
Inclination 126.356±0.064°
Satellite of Haumea
Physical characteristics
Mean radius
~160 km [1]
Mass (1.79±0.11)×1019  kg [1] (0.45% of Haumea)
Mean density
~1  g/cm3
~9.8 h [2]
Albedo 0.8±0.07 [3] [1]
Temperature 32±3  K
20.3 (3.0 difference from primary's 17.3) [3]

    Hiʻiaka is the larger, outer moon of the trans-Neptunian dwarf planet Haumea. It is named after one of the daughters of Haumea, Hiʻiaka, the patron goddess of the Big Island of Hawaii. It orbits once every 49.12±0.03 d at a distance of 49880±198  km , with an eccentricity of 0.0513±0.0078 and an inclination of 126.356±0.064°. Assuming its estimated diameter of over 300 km is accurate, it may be the fourth- or fifth-largest known moon of a Trans-Neptunian object, after Pluto I Charon, Eris I Dysnomia, Orcus I Vanth, very possibly Varda I Ilmarë, and perhaps Salacia I Actaea.

    Contents

    Discovery

    Hiʻiaka was the first satellite discovered around Haumea. It was discovered on 26 January 2005 and nicknamed "Rudolph" by the discovery team before being assigned an official name.

    Physical characteristics

    Size and brightness

    Its measured brightness is 5.9±0.5%, translating into a diameter of about 22% of its primary, or in the range of 320 km, assuming similar infrared albedo. [1] To put this in perspective, if Hi'iaka were in the asteroid belt, it would be larger than all but the four largest asteroids, after 1 Ceres, 2 Pallas, 4 Vesta, and 10 Hygiea. In spite of its relatively large size, however, lightcurve studies suggest that Hi'iaka is not a gravitationally collapsed spheroid; they further suggest that Hi'iaka is not tidally locked and has a rotation period of about 9.8 hours. [2]

    Mass

    The mass of Hiʻiaka is estimated to be (1.79±0.11)×1019  kg using precise relative astrometry from Hubble Telescope and Keck Telescope and applying 3-body, point-mass model to the Haumean system. [1]

    Spectrum and composition

    The near infrared spectrum of Hiʻiaka is dominated by water-ice absorption bands, which means that its surface is made mainly of water ice. The presence of the band centered at 1.65 μm indicates that the surface water ice is primarily in the crystalline form. Currently it is unclear why water ice on the surface has not turned into amorphous form as would be expected due to its constant irradiation by cosmic rays. [4]

    See also

    Notes

        Related Research Articles

        Kuiper belt Area of the Solar System beyond the planets, comprising small bodies

        The Kuiper belt is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times as wide and 20–200 times as massive. Like the asteroid belt, it consists mainly of small bodies or remnants from when the Solar System formed. While many asteroids are composed primarily of rock and metal, most Kuiper belt objects are composed largely of frozen volatiles, such as methane, ammonia, and water. The Kuiper belt is home to three objects identified as dwarf planets by the IAU: Pluto, Haumea, and Makemake. Some of the Solar System's moons, such as Neptune's Triton and Saturn's Phoebe, may have originated in the region.

        Nereid (moon) Large moon of Neptune

        Nereid, or Neptune II, is the third-largest moon of Neptune. Of all known moons in the Solar System, it has the most eccentric orbit. It was the second moon of Neptune to be discovered, by Gerard Kuiper in 1949.

        28978 Ixion Plutino

        28978 Ixion, provisional designation 2001 KX76, is a large trans-Neptunian object and a possible dwarf planet. It is located in the Kuiper belt, a region of icy objects orbiting beyond Neptune in the outer Solar System. Ixion is classified as a plutino, a dynamical class of objects in a 2:3 orbital resonance with Neptune. It was discovered in May 2001 by astronomers of the Deep Ecliptic Survey at the Cerro Tololo Inter-American Observatory, and was announced in July 2001. The object is named after the Greek mythological figure Ixion, who was a king of the Lapiths.

        90482 Orcus Trans-Neptunian object and dwarf planet

        Orcus is a trans-Neptunian dwarf planet with a large moon, Vanth. It has a diameter of 910 km (570 mi). The surface of Orcus is relatively bright with albedo reaching 23 percent, neutral in color and rich in water ice. The ice is predominantly in crystalline form, which may be related to past cryovolcanic activity. Other compounds like methane or ammonia may also be present on its surface. Orcus was discovered by American astronomers Michael Brown, Chad Trujillo, and David Rabinowitz on 17 February 2004.

        Haumea Dwarf planet in the Solar System

        Haumea is a dwarf planet located beyond Neptune's orbit. It was discovered in 2004 by a team headed by Mike Brown of Caltech at the Palomar Observatory in the United States and disputably also in 2005 by a team headed by José Luis Ortiz Moreno at the Sierra Nevada Observatory in Spain, though the latter claim has been contested. On September 17, 2008, it was named after Haumea, the Hawaiian goddess of childbirth, under the expectation by the International Astronomical Union (IAU) that it would prove to be a dwarf planet. Nominal estimates make it the third-largest known trans-Neptunian object, after Eris and Pluto, though the uncertainty in best-fit modeling slightly overlaps with the larger size estimates for Makemake.

        Makemake Dwarf planet in the Outer Solar System

        Makemake is a dwarf planet and perhaps the second-largest Kuiper belt object in the classical population, with a diameter approximately two-thirds that of Pluto. It has one known satellite. Its extremely low average temperature, about 40 K (−230 °C), means its surface is covered with methane, ethane, and possibly nitrogen ices.

        <span class="nowrap">(19308) 1996 TO<sub>66</sub></span> Trans-Neptunian object in the Kuiper belt

        (19308) 1996 TO66 (also written (19308) 1996 TO66) is a trans-Neptunian object that was discovered in 1996 by Chadwick Trujillo, David Jewitt and Jane Luu. Until 20000 Varuna was discovered, it was the second-largest known object in the Kuiper belt, after Pluto.

        38628 Huya Trans-Neptunian object

        38628 Huya ( hoo-YAH), provisional designation 2000 EB173, is a binary trans-Neptunian object located in the Kuiper belt, a region of icy objects orbiting beyond Neptune in the outer Solar System. Huya is classified as a plutino, a dynamical class of trans-Neptunian objects with orbits in a 3:2 orbital resonance with Neptune. It was discovered by the Quasar Equatorial Survey Team and was identified by Venezuelan astronomer Ignacio Ferrín in March 2000. It is named after Juyá, the mythological rain god of the Wayuu people native to South America.

        <span class="nowrap">(55636) 2002 TX<sub>300</sub></span>

        (55636) 2002 TX300 is a bright Kuiper belt object in the outer Solar System estimated to be about 286 kilometres (178 mi) in diameter. It is a large member of the Haumea family that was discovered on 15 October 2002 by the Near-Earth Asteroid Tracking (NEAT) program.

        Namaka (moon) Smaller moon of Haumea

        Namaka is the smaller, inner moon of the trans-Neptunian dwarf planet Haumea. It is named after Nāmaka, the goddess of the sea in Hawaiian mythology and one of the daughters of Haumea.

        <span class="nowrap">(208996) 2003 AZ<sub>84</sub></span> Plutino

        (208996) 2003 AZ84 is a trans-Neptunian object with a possible moon from the outer regions of the Solar System. It is approximately 940 kilometers across its longest axis, as it has an elongated shape. It belongs to the plutinos – a group of minor planets named after its largest member Pluto – as it orbits in a 2:3 resonance with Neptune in the Kuiper belt. It is the third-largest known plutino, after Pluto and Orcus. It was discovered on 13 January 2003, by American astronomers Chad Trujillo and Michael Brown during the NEAT survey using the Samuel Oschin telescope at Palomar Observatory.

        (24835) 1995 SM55, provisional designation 1995 SM55, is a trans-Neptunian object and member of the Haumea family that resides in the Kuiper belt, located in the outermost region of the Solar System. It was discovered on 19 September 1995, by American astronomer Nichole Danzl of the Spacewatch program at Kitt Peak National Observatory near Tucson, Arizona, in the United States. It measures approximately 200 kilometers in diameter and was the second-brightest known object in the Kuiper belt, after Pluto, until 1996 TO66 was discovered.

        <span class="nowrap">(120178) 2003 OP<sub>32</sub></span>

        (120178) 2003 OP32, also written as (120178) 2003 OP32, is a trans-Neptunian object (TNO) that resides in the Kuiper belt. It was discovered on July 26, 2003 by Michael E. Brown, Chad Trujillo and David L. Rabinowitz at Palomar Mountain in California.

        <span class="nowrap">(145453) 2005 RR<sub>43</sub></span>

        (145453) 2005 RR43, also written as (145453) 2005 RR43, is a trans-Neptunian object (TNO) estimated to be about 250 km in diameter. It was discovered on 9 September 2005 by Andrew Becker, Andrew Puckett and Jeremy Kubica at Apache Point Observatory in Sunspot, New Mexico.

        Moons of Haumea Natural satellites orbiting dwarf planet Haumea

        The outer Solar System planetoid Haumea has two known moons, Hiʻiaka and Namaka, named after Hawaiian goddesses. These small moons were discovered in 2005, from observations of Haumea made at the large telescopes of the W. M. Keck Observatory in Hawaii.

        Haumea family

        The Haumea or Haumean family is the only identified trans-Neptunian collisional family; that is, the only group of trans-Neptunian objects (TNOs) with similar orbital parameters and spectra that suggest they originated in the disruptive impact of a progenitor body. Calculations indicate that it is probably the only trans-Neptunian collisional family. Members are known as Haumeids.

        225088 Gonggong Dwarf planet in the scattered-disc

        Gonggong (225088 Gonggong or provisional designation: 2007 OR10) is a dwarf planet, a member of the scattered disc beyond Neptune. It has a highly eccentric and inclined orbit during which it ranges from 34–101 astronomical units (5.1–15.1 billion kilometers; 3.2–9.4 billion miles) from the Sun. As of 2019, its distance from the Sun is 88 AU (13.2×10^9 km; 8.2×10^9 mi), and it is the sixth-farthest known Solar System object. Gonggong is in a 3:10 orbital resonance with Neptune, in which it completes three orbits around the Sun for every ten orbits completed by Neptune. Gonggong was discovered in July 2007 by American astronomers Megan Schwamb, Michael Brown, and David Rabinowitz at the Palomar Observatory, and the discovery was announced in January 2009.

        (469306) 1999 CD158, provisional designation: 1999 CD158, is a trans-Neptunian object from the circumstellar disc of the Kuiper belt, located in the outermost region of the Solar System. The relatively bright hot classical Kuiper belt object measures approximately 310 kilometers (190 miles) in diameter. It was discovered on 10 February 1999, by American astronomers Jane Luu, David Jewitt and Chad Trujillo at Mauna Kea Observatories on the Big Island of Hawaii, United States.

        <span class="nowrap">(416400) 2003 UZ<sub>117</sub></span>

        (416400) 2003 UZ117 is a trans-Neptunian object and suspected member of the Haumea family, located in the Kuiper belt in the outermost region of the Solar System. It was discovered on 24 October 2003, by astronomers of the Spacewatch survey project at Kitt Peak Observatory, Arizona. The object may also be a non-resonant cubewano.

        References

        1. 1 2 3 4 5 6 Ragozzine, D.; Brown, M. E. (2009). "Orbits and Masses of the Satellites of the Dwarf Planet Haumea (2003 EL61)". The Astronomical Journal. 137 (6): 4766–4776. arXiv: 0903.4213 . Bibcode:2009AJ....137.4766R. doi:10.1088/0004-6256/137/6/4766.
        2. 1 2 Hastings, Danielle M.; Ragozzine, Darin; Fabrycky, Daniel C.; Burkhart, Luke D.; Fuentes, Cesar; Margot, Jean-Luc; Brown, Michael E.; Holman, Matthew (December 2016). "The Short Rotation Period of Hi'iaka, Haumea's Largest Satellite". The Astronomical Journal. 152 (6): 12. arXiv: 1610.04305 . Bibcode:2016AJ....152..195H. doi:10.3847/0004-6256/152/6/195. OCLC   6889796157. OSTI   22662917. 195.
        3. 1 2 Wm. Robert Johnston (17 September 2008). "(136108) Haumea, Hi'iaka, and Nāmaka" . Retrieved 18 September 2008.
        4. Dumas, C.; Carry, B.; Hestroffer, D.; Merlin, F. (2011). "High-contrast observations of (136108) Haumea". Astronomy & Astrophysics. 528: A105. arXiv: 1101.2102 . Bibcode:2011A&A...528A.105D. doi:10.1051/0004-6361/201015011.