10 Hygiea

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10 Hygiea
SPHERE image of Hygiea.jpg
VLT-SPHERE image of Hygiea
Discovery [1]
Discovered by A. de Gasparis
Discovery site Astronomical Observatory of Capodimonte
Discovery date12 April 1849
Designations
(10) Hygiea
Pronunciation /haɪˈdʒiːə/ [2]
Named after
 Hygieia [3]
A849 GA ·A900 GA
Main belt (Hygiea family)
Adjectives Hygiean /haɪˈdʒiːən/ [4]
Symbol Hygiea symbol (original, bold).svg (historical astronomical), Hygiea symbol (bold).svg (modern astrological)
Orbital characteristics [1]
Epoch 27 April 2019 (JD 2458600.5)
Uncertainty parameter 0
Observation arc 170.23 yr (62,175 days)
Aphelion 3.4948 AU
Perihelion 2.7882 AU
3.1415 AU
Eccentricity 0.1125
5.57 yr (2033.8 days)
Average orbital speed
16.76 km/s
152.18°
Inclination 3.8316°
283.20°
312.32°
Proper orbital elements [5]
3.14178  AU
Proper eccentricity
0.1356
Proper inclination
5.1039°
Proper mean motion
64.6218  deg  / yr
5.57088 yr
(2034.762 d)
Precession of perihelion
128.544  arcsec  / yr
Precession of the ascending node
−96.9024  arcsec  / yr
Physical characteristics
Dimensions 450 km × 430 km × 424 km
± 10 km × 10 km × 20 km
433±8 km [6]
434±14 km [7]
Flattening 0.06 [a]
Mass (8.74±0.69)×1019 kg [6]
(8.32±0.80)×1019 kg (representative) [8]
Mean density
2.06±0.20 g/cm3 [6]
1.94±0.19 g/cm3 [8]
13.82559±0.00005 h [7]
0.063 [6]
0.0717±0.002 [1]
Temperature ≈164 K
max: 247 K (−26°C) [9]
C-type [1]
9.0 [10] to 11.97
5.64 [1]
0.321″ to 0.133″

    10 Hygiea is a large asteroid located in the main asteroid belt. With a mean diameter of between 425 and 440 km and a mass estimated to be 3% of the total mass of the belt, [11] it is the fourth-largest asteroid in the Solar System by both volume and mass, and is the largest of the C-type asteroids (dark asteroids with a carbonaceous surface) in classifications that use G type for 1 Ceres. It is very close to spherical, apparently because it had re-accreted after the disruptive impact that produced the large Hygiean family of asteroids.

    Contents

    History

    Discovery

    Annibale de Gasparis discovered Hygiea on 12 April 1849 Annibale De Gasparis.gif
    Annibale de Gasparis discovered Hygiea on 12 April 1849

    Hygiea was discovered on the evening of 12 April 1849 by Italian astronomer Annibale de Gasparis at the Astronomical Observatory of Capodimonte in Naples, Italy. [12] : XV  [13] : 10  On that night he was using the observatory's Reichenbach equatorial telescope (8.3 cm; 3.3 in diameter lens, 120 cm; 47 in focal length) [14] [13] : 9  to observe a section of the sky in the 12th hour of right ascension, as part of his larger project of cataloguing stars along the ecliptic up to the 14th apparent magnitude. [12] : XV–XVI  [13] : 10  While comparing his observations to the Berlin Academy's star chart, [13] : 10  [b] de Gasparis noticed a bright, starlike object between magnitude 9 and 10 which was not recorded before. [17] : 126  [13] : 10  [c] Although poor weather prevented further observations for a few days, de Gasparis reobserved the object on 14 and 17 April and confirmed it had moved between these dates. [17] : 126  [16] Judging by how much the object had moved, de Gasparis concluded it must be another new planet [d] between the orbit of Mars and Jupiter. [17] : 126  De Gasparis announced his discovery to Erasmo Fabri Scarpellini, [20] : 28  secretary of the Correspondenza Scientifica bulletin at Rome, Italy, [17] : 126  who in turn passed on the news to Heinrich Christian Schumacher, who published in the Astronomische Nachrichten journal on 11 May 1849. [16] [19] Hygiea was the first asteroid discovered by de Gasparis and the tenth asteroid discovered in history. [19] [21] : 80  He would later discover another six asteroids between 1850 and 1853 and two more during the 1860s. [19]

    Name

    De Gasparis invited Ernesto Capocci Belmonte, his friend and director of the Capodimonte Observatory, to assign a name to the asteroid as gratitude for his help and advice. [12] : XVI  [13] : 10  Capocci suggested the name Igea—the Italian spelling of Hygieia, the Greek goddess of health and daughter of Asclepius. [14] [13] : 10  De Gasparis added the adjective Borbonica to Capocci's suggested name, to honor King Ferdinand II of the Bourbons of Naples who ruled the Kingdom of the Two Sicilies and supported the work of the Capodimonte Observatory. [22] [12] : XVI  Together, de Gasparis and Capocci proposed the name Igea Borbonica ("Bourbon Hygieia") in a letter forwarded to Ferdinand II on 8 May 1849. [23] [13] : 10  De Gasparis's commemoration of the Bourbons may have helped him and Capocci circumvent punishment for their participation in the liberal movements of 1848. [24]

    The name Igea Borbonica was not mentioned in the first communications to the European scientific community. [13] : 10  When English astronomer John Herschel received the news of Hygiea's discovery from his Neapolitan colleagues, [13] : 10  he suggested that Parthenope would be an appropriate name for de Gasparis's discovery, as it comes from the siren who founded Naples in Greek mythology. [19] [17] : 127  In a letter written to English mathematician Augustus De Morgan in April 1849, Herschel wrote:

    No name has yet been mentioned. What do you think of Parthenope (being a Neapolitan?) I should think it will occur as a matter of course to Gasparis if he has any classical reading.

    — John Herschel, in a letter to Augustus De Morgan (April 1849) [14] [13] : 10–11 

    Herschel corresponded with other European scientists and astronomers to hear their thoughts on the name Parthenope for de Gasparis's discovery, although by the time he reached out to de Gasparis, Hygiea had already been named one month earlier. [14] When Schumacher, editor of Astronomische Nachrichten, learned of the name proposed by de Gasparis and Capocci, he complained in a letter addressed to Herschel on 26 June 1849 that it had the Italian spelling instead of the Latin form, as conventionally done for all the other planets. [14] Regardless, de Gasparis recognized Herschel's suggestion and expressed desire to realize Herschel's wish. [14] [17] : 167  On 11 May 1850, de Gasparis discovered the asteroid 11 Parthenope and acknowledged Herschel for the name in his announcement. [19]

    There are multiple variations on the Latin spelling of Hygiea, including Hygièa, Hygia, and Hygea. [14] [25] The modern English form Hygiea is a less common variant of the name of the goddess, which in Greek is Ὑγίεια (Hygieia) [26] or Ὑγεῖα (Hygeia). [27] The name was often spelled Hygeia (and occasionally Hygea [28] [21] : 80 ) by astronomers during the early 1850s, though by the 1860s, the spelling Hygiea became commonplace. [29] The Borbonica adjective was dropped as it was considered an "unnecessary appendage" according to English astronomer John Russell Hind in 1852. [17] : 126 

    Symbol and designation

    As with the other previously discovered asteroids, Hygiea was given an astronomical symbol as a way of representing it. The symbol for Hygiea was proposed by de Gasparis in a letter addressed to Hind on 4 November 1850, in which he wrote, "The symbol of Hygeia [ sic ] is a serpent (like a Greek ζ ) crowned with a star." [30] Visually, de Gasparis's symbol for Hygiea is depicted as: Hygiea symbol (original, fixed width).svg (U+1F779 🝹 in Unicode 17.0). [31] : 7  [32] The serpent, particularly when drinking from a bowl, is a traditional symbol of the goddess Hygieia (cf. U+1F54F 🕏). [33]

    However, perhaps due to the late announcement of Hygiea's intended symbol, it was not used in following astronomical almanacs such as the Berliner Astronomisches Jahrbuch in 1850 and the Nautical Almanac and Astronomical Ephemeris in 1852, marking the first time an asteroid was listed without its symbol in these almanacs. [31] : 7  American astronomer Benjamin Apthorp Gould interpreted Hygiea's symbol as a rod of Asclepius, depicting it as a serpent coiled around a staff in a January 1852 publication of the Astronomical Journal : Rod of Asclepius (fixed width).svg (U+2695 ⚕). [21] : 80  [31] : 7 

    Both symbols of Hygiea are now largely obsolete as the number of asteroids discovered had grown too much for each to have unique symbols. [34] [21] : 80  In 1851 Johann Franz Encke proposed a different identification system, suggesting using a number corresponding to the order of discovery enclosed in a small circle [34] [31] : 5 —for Hygiea it would be ⑩. [21] : 80  Astronomers began adopting Encke's circled number scheme in scientific publications, though as the number of asteroids discovered grew, astronomers eventually switched to enclosing the number in parentheses, which became the modern minor-planet designation scheme. [34] [31] : 5  In the case of Hygiea, its modern minor planet designation would be (10) Hygiea [35] or 10 Hygiea. [1]

    The Minor Planet Center uses the minor planet provisional designations A849 GA and A900 GA for Hygiea, [35] though these are only retrospective extensions of the new-style provisional designation scheme established in 1925. [36] While the provisional designation A849 GA refers to the discovery date of Hygiea, the designation A900 GA refers to the date when Hygiea was serendipitously observed and catalogued (as Arequipa 38 [37] : 13 ) by the Harvard College Observatory's photographic sky survey at Arequipa, Peru in 1900. [38] [35] [e]

    Hygiea has seen some minor astrological use, though its symbol was confused once again, with Asclepsius's rod replaced by Mercury's caduceus: Hygiea symbol (fixed width).svg , though in a more elaborate form (U+2BDA ⯚) than the caduceus symbol of the planet Mercury. [31] : 6  [39] : 11  The caduceus has long been mistaken for the rod of Asclepius (see caduceus as a symbol of medicine).

    Classification

    This graphic used in the IAU 2006 draft proposal listed Hygiea as a potential planet. Iau dozen.jpg
    This graphic used in the IAU 2006 draft proposal listed Hygiea as a potential planet.

    While the first four asteroids discovered—Ceres (1801), Pallas (1802), Juno (1804), and Vesta (1807)—were considered planets during the first half of the 19th century (with some astronomers continuing to consider them as such until the end of the century), the discovery of Hygiea occurred when the classification of asteroids was already evolving. [34] Hygiea was referred to as a planet in the following years after its discovery, [14] though by 1852 astronomers have also called Hygiea a minor planet [17] : 127  or an asteroid. [21] : 80  These new terms were introduced prior to Hygiea's discovery and became more used with the discovery of more asteroids beginning in the 1850s. [34] From the second half of the 19th century, asteroids began to be treated in a predominantly collective way, grouped according to orbital or spectral characteristics, with less attention to the individual object. [41]

    In 2006, the International Astronomical Union's committee for drafting a new definition of planet had considered classifying Hygiea among the planets or the newly-coined category of dwarf planets, if it were found that the asteroid is massive enough to be shaped predominantly by hydrostatic equilibrium. [42] : 238  [40] : 17  [43] : 50  Since 2019, telescope images have resolved Hygiea's nearly spherical shape, suggesting that it may have reached hydrostatic equilibrium, and thus could be considered a dwarf planet. If so, Hygiea would be the smallest dwarf planet known. [44]

    Observation

    Image of 10 Hygiea taken by the 2MASS survey 10 Hygiea 2MASS.jpg
    Image of 10 Hygiea taken by the 2MASS survey

    Despite its size, Hygiea appears very dim when observed from Earth. This is due to its dark surface and its position in the outer main belt. For this reason, six smaller asteroids were observed before Annibale de Gasparis discovered Hygiea on 12 April 1849.

    Although it is the largest body in its region, due to its dark surface and farther-than-average distance from the Sun, Hygiea appears very dim when observed from Earth. In fact, it is the third dimmest of the first twenty-three asteroids discovered, with only 13 Egeria and 17 Thetis having lower mean opposition magnitudes. [45] At most oppositions, Hygiea has a magnitude of around +10.2, [45] which is as much as four orders fainter than Vesta, and observation calls for at least a 4-inch (100 mm) telescope to resolve. [46] However, at a perihelic opposition, Hygiea can reach +9.1 magnitude and may just be resolvable with 10 × 50 binoculars, unlike the next two largest asteroids in the asteroid belt, 704 Interamnia and 511 Davida, which are always beyond binocular visibility. [47]

    A total of 17 stellar occultations by Hygiea have been tracked by Earth-based astronomers, [48] [49] including two (in 2002 and 2014) that were seen by a large number of observers. The observations have been used to constrain Hygiea's size, shape and rotation axis. [50] The Hubble Space Telescope has resolved the asteroid and ruled out the presence of any orbiting companions larger than about 16 kilometres (9.9 mi) in diameter. [51]

    Physical characteristics

    Relative sizes of the four largest asteroids. Hygiea is furthest right. The Four Largest Asteroids.jpg
    Relative sizes of the four largest asteroids. Hygiea is furthest right.
    VLT-SPHERE images of asteroid 10 Hygiea, taken in June/July 2017. A bright surface feature and several dark craters are visible on the surface. At the time, the southern hemisphere of Hygiea was facing Earth. Hygiea imaging SPHERE.png
    VLT-SPHERE images of asteroid 10 Hygiea, taken in June/July 2017. A bright surface feature and several dark craters are visible on the surface. At the time, the southern hemisphere of Hygiea was facing Earth.

    Observations taken with the Very Large Telescope's SPHERE imager in 2017 and 2018 revealed that Hygiea is nearly spherical and is close to a hydrostatic equilibrium shape and thus is a possible dwarf planet. [7] Based on spectral evidence, Hygiea's surface is thought to consist of primitive carbonaceous materials similar to those found in carbonaceous chondrite meteorites. Aqueous alteration products have been detected on its surface, which could indicate the presence of water ice in the past which was heated sufficiently to melt. [52] The primitive present surface composition indicates that Hygiea had not melted during the early period of Solar System formation. [52] However, observations suggest Hygiea suffered a major collision early in its history that completely disrupted it, with its present spherical shape due to re-accretion of the disrupted material. [6] No deep basins are visible in VLT images, indicating that any large craters that formed after re-accretion must have flat floors, consistent with an icy C-type composition. [7]

    In images taken with the VLT in 2017, a bright surface feature is visible, as well as at least two dark craters, which have been informally [f] named Serpens and Calix after the Latin words for 'snake' and 'cup', respectively. [8] Serpens has a diameter of 180 km, Calix of 90 km. [8] [7]

    Hygiea is the largest of the class of dark C-type asteroids that are dominant in the outer asteroid belt, beyond the Kirkwood gap at 2.82 AU. [53] Its mean diameter 433±8 km. [6] Hygiea is close to spherical, with an axis ratio of 0.94±0.05 that is consistent with a MacLaurin ellipsoid. [6] Aside from being the smallest of the "big four", Hygiea has a relatively low density of 2.06±0.20, [6] comparable to Ceres (2.16) and the larger icy satellites of the Solar System (Ganymede 1.94, Callisto 1.83, Titan 1.88, Triton 2.06) rather than to Pallas (2.9±0.1) or Vesta (3.45).

    Orbit and rotation

    A diagram of 10 Hygiea's orbit, with the inner planets' and Jupiter's orbits labelled. 10 Hygiea orbit.jpg
    A diagram of 10 Hygiea's orbit, with the inner planets' and Jupiter's orbits labelled.

    Orbiting at an average of 3.14 AU from the Sun, Hygiea is the most distant of the "big four" asteroids. It lies closer to the ecliptic as well, with an orbital inclination of 4°. [52] Its orbit is less circular than those of Ceres or Vesta, with an eccentricity of around 0.12. [1] Its perihelion is at a quite similar longitude to those of Vesta and Ceres, though its ascending and descending nodes are opposite to the corresponding ones for those objects. Although its perihelion is extremely close to the mean distance of Ceres and Pallas, a collision between Hygiea and its larger companions is impossible because at that distance they are always on opposite sides of the ecliptic.[ citation needed ] In 2056, Hygiea will pass 0.025 AU from Ceres, and then in 2063, Hygiea will pass 0.020 AU from Pallas. [54] [ failed verification ] At aphelion Hygiea reaches out to the extreme edge of the asteroid belt at the perihelia of the Hilda family, which is in a 3:2 orbital resonance with Jupiter. [55]

    As one of the most massive asteroids, Hygiea is used by the Minor Planet Center to calculate perturbations. [56]

    Hygiea is in an unstable three-body mean motion resonance with Jupiter and Saturn. [57] The computed Lyapunov time for this asteroid is 30,000 years, indicating that it occupies a chaotic orbit that will change randomly over time because of gravitational perturbations by the planets. [57] It is the lowest numbered asteroid in such a resonance (the next lowest numbered being 70 Panopaea). [57] [58]

    Hygiea has a rotation period of 13.83 hours. [7] Its single-peaked light curve has an amplitude of 0.27 mag, [8] which is largely attributed to albedo variations. [7] Hygiea's north pole points towards ecliptic longitude 306°±3° and ecliptic latitude −29°±3°, [6] which gives an axial tilt of 119° with respect to the ecliptic. [6]

    Hygiea family

    Location and structure of the Hygiea family Hygiea family.png
    Location and structure of the Hygiea family

    Hygiea is the main member of the Hygiean asteroid family that constitutes about 1% of asteroids in the main belt.[ citation needed ] The family was formed when an object with a diameter of about 100 km collided with proto-Hygiea about 2 billion years ago. Because the impact craters on Hygiea today are too small to contain the volume of ejected material, it is thought that Hygiea was completely disrupted by the impact and that the majority of the debris recoalesced after the pieces that formed the rest of the family had escaped. Hygiea contains almost all the mass (over 98%) of the family. [7]

    Exploration

    Hygiea has not been explored by any space probe. However, the exploration of main-belt asteroids, especially primitive objects like Hygiea, could provide clues to the process that led to the formation of the solar system. [59] [60] : 1  In 2006, Mark V. Sykes and others from the Planetary Science Institute proposed the Exploring the Very Earliest Epoch (EVE) mission to NASA, as part of the Discovery Program. The proposal, which did not get approved, suggested launching a copy of the Dawn probe to Hygiea in October 2011 and arriving to the asteroid via rendezvous in 2021. [60] : 1–2  In 2013, [61] : 431  Pierre Vernazza and Philippe Lamy proposed the medium-class mission INSIDER for the European Space Agency's Space Programme. [59] The proposal, which also did not get approved, suggested rendezvousing and orbiting around two or three large main-belt asteroids before releasing one or two landers. Hygeia and 24 Themis were among the potential targets of the INSIDER mission concept. [59]

    See also

    Notes

    1. ↑ Flattening derived from the maximum aspect ratio (c/a): , where (c/a) = 0.94±0.05. [6]
    2. ↑ The Berlin Academy star chart, which was published in years between 1830 and 1859, was compiled by a collaboration of astronomers who were each allotted a section of the sky spanning one hour of right ascension. [15] : 367  The stars in the 12th (XXII) hour of right ascension were charted by Carl August von Steinheil, [15] : 368  whose map aided de Gasparis's discovery of Hygiea. [16] [17] : 126  [12] : XVI 
    3. ↑ Hygiea was located at the 12th hour of right ascension in the sky at the time of its discovery. [18]
    4. ↑ Asteroids were referred to as "planets" at the time of Hygiea's discovery. These would eventually be recategorized as "minor planets". [19]
    5. ↑ In the new-style provisional designation scheme for pre-1925 minor planet discoveries, the designation begins with the letter A followed by three digits corresponding to the year of discovery ("A849" for 1849, and "A900" for 1900) and ends with two letters, with the first indicating the discovery date's half-month ("G" for the first half of April) and the second indicating the order of discovery in that half-month ("A" meaning first minor planet discovered in that half-month). [36]
    6. ↑ Pending approval by the IAU.

    References

    1. 1 2 3 4 5 6 7 "JPL Small-Body Database Lookup: 10 Hygiea (A849 GA)" (2025-01-13 last obs.). Jet Propulsion Laboratory . Retrieved 28 March 2025.
    2. ↑ "Hygeia" . Oxford English Dictionary (Online ed.). Oxford University Press.(Subscription or participating institution membership required.)
    3. ↑ Schmadel, L. D. (2007). "(10) Hygiea". Dictionary of Minor Planet Names – (10) Hygiea. Springer Berlin Heidelberg. p. 16. doi:10.1007/978-3-540-29925-7_11. ISBN   978-3-540-29925-7.
    4. ↑ "hygeian" . Oxford English Dictionary (Online ed.). Oxford University Press.(Subscription or participating institution membership required.)
    5. ↑ "AstDyS-2 Hygiea Synthetic Proper Orbital Elements". Department of Mathematics, University of Pisa, Italy. Archived from the original on 15 November 2020. Retrieved 28 April 2019.
    6. 1 2 3 4 5 6 7 8 9 10 11 P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics 54, A56
    7. 1 2 3 4 5 6 7 8 Vernazza, P.; Jorda, L.; Ševeček, P.; Brož, M.; Viikinkoski, M.; Hanuš, J.; et al. (2020). "A basin-free spherical shape as an outcome of a giant impact on asteroid Hygiea" (PDF). Nature Astronomy. 273 (2): 136–141. Bibcode:2020NatAs...4..136V. doi:10.1038/s41550-019-0915-8. hdl: 10045/103308 . S2CID   209938346. Archived (PDF) from the original on 11 November 2020. Retrieved 28 October 2019.
    8. 1 2 3 4 5 Vernazza, P.; Jorda, L.; Ševeček, P.; Brož, M.; Viikinkoski, M.; Hanuš, J.; et al. (28 October 2019). "A basin-free spherical shape as an outcome of a giant impact on asteroid Hygiea, Supplementary Information" (PDF). Nature Astronomy. 4. Bibcode:2020NatAs...4..136V. doi:10.1038/s41550-019-0915-8. hdl: 10045/103308 . S2CID   209938346. Archived (PDF) from the original on 29 November 2021. Retrieved 30 October 2019.
    9. ↑ Lim, L. F.; McConnochie, T.; Belliii, J.; Hayward, T. (2005). "Thermal infrared (8–13 μm) spectra of 29 asteroids: the Cornell Mid-Infrared Asteroid Spectroscopy (MIDAS) Survey". Icarus. 173 (2): 385. Bibcode:2005Icar..173..385L. doi:10.1016/j.icarus.2004.08.005.
    10. ↑ "AstDys (10) Hygiea Ephemerides". Department of Mathematics, University of Pisa, Italy. Archived from the original on 24 July 2020. Retrieved 26 June 2010.
    11. ↑ "Mass of 10 Hygiea" 0.445 / "Mass of Mbelt" Archived 2008-10-31 at the Wayback Machine 15 = 0.0296
    12. 1 2 3 4 5 de Ritis, Vincenzo (1852). "Cenno de' lavori accademici e dell'azione governativa ne' reali domini continentali dal 1848 al primo semestre del 1852". In Murena, Salvatore (ed.). Annali Civili del Regno delle Due Sicilie (in Italian). Vol. 46. Naples, Italy: Tipografia del Real ministero degli affari interni. pp. XIII–XXI. Archived from the original on 27 November 2024.
    13. 1 2 3 4 5 6 7 8 9 10 11 Gargano, Maruo (April 2023). "Annibale de Gasparis, the sublime calculator of Parthenope's sky". Bulletin of Regional Natural History. 3 (1): 1–24. doi: 10.6093/2724-4393/9975 .
    14. 1 2 3 4 5 6 7 8 Palma, Paolo (5 November 2019). "A Parthenope in the sky". The Royal Society. Archived from the original on 16 January 2025. Retrieved 27 March 2025.
    15. 1 2 Jones, Derek (2002). "Akademische Sternkarten, Berlin 1830—59". Highlights of Astronomy. 12: 367–370. Bibcode:2002HiA....12..367J. doi: 10.1017/S1539299600013770 .
    16. 1 2 3 Schumacher, H. C. (11 May 1849). "Planeten Circular". Astronomische Nachrichten (in German). 28 (672): 391. Bibcode:1849AN.....28..391A. doi:10.1002/asna.18490282604.
    17. 1 2 3 4 5 6 7 8 9 Hind, John Russell (1852). "Chapter VIII. The Minor or Ultra-Zodiacal Planets.". The Solar System: Descriptive Treatise Upon the Sun, Moon, and Planets, Including an Account of All the Recent Discoveries. New York, United States: G. P. Putnam's Sons. p. 126.
    18. ↑ "JPL Horizons On-Line Ephemeris for 10 Hygiea (A849 GA) on 1849 Apr 12–1849 Apr 13". JPL Horizons On-Line Ephemeris System . Jet Propulsion Laboratory. Retrieved 26 March 2025. Ephemeris Type: Observer and Center: 500@399 (geocentric)
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    21. 1 2 3 4 5 6 Gould, B. A. (January 1852). "On the symbolic notation of the asteroids". The Astronomical Journal. 2: 80. Bibcode:1852AJ......2...80G. doi:10.1086/100212.
    22. ↑ Badolati, Ennio (2007). "Gasparis, Annibale de". In Hockey, Thomas (ed.). The Biographical Encyclopedia of Astronomers. Springer, New York, NY. p. 408. doi:10.1007/978-0-387-30400-7_502. ISBN   978-0-387-30400-7.
    23. ↑ de Gasparis, Annibale (8 May 1849). "Lettera a Ernesto Capocci" (in Italian). Letter to Capocci, Ernesto. Ministero Pubblica Istruzione. F. 428, f. 3: Archivio di Stato di Napoli. Retrieved 27 March 2025.{{cite press release}}: CS1 maint: location (link)
    24. ↑ Mancuso, Santi (1988). "DE GASPARIS, Annibale". Dizionario Biografico degli Italiani . 36. Treccani . Retrieved 27 March 2025.
    25. ↑ Lewis, Charlton T.; Short, Charles. "Hygēa or Hygīa (Hygĭeia)". A Latin Dictionary. Perseus Digital Library. Archived from the original on 12 May 2024. Retrieved 28 March 2025.
    26. ↑ Liddell, Henry George; Scott, Robert. "Ὑγίεια". A Greek-English Lexicon. Perseus Digital Library. Archived from the original on 5 December 2022. Retrieved 28 March 2025.
    27. ↑ Liddell, Henry George; Scott, Robert. "ὑγεῖα". A Greek-English Lexicon. Perseus Digital Library. Archived from the original on 5 December 2022. Retrieved 28 March 2025.
    28. ↑ Ferguson, James (June 1850). "Observations of Astræa and Hygea". The Astronomical Journal. 1 (10): 74–76. Bibcode:1850AJ......1...74F. doi:10.1086/100046.
    29. ↑ "ADS Search Query: "hygeia" OR "hygiea"". Astrophysics Data System . SAO/NASA. Retrieved 28 March 2025.
    30. ↑ de Gasparis, Annibale (November 1850). "Letter to Mr. Hind, from Professor Annibale de Gasparis". Monthly Notices of the Royal Astronomical Society. 11: 1. Bibcode:1850MNRAS..11....1D. doi: 10.1093/mnras/11.1.1a . The symbol of Hygeia is a serpent (like a Greek ζ) crowned with a star.
    31. 1 2 3 4 5 6 Bala, Gavin Jared; Miller, Kirk (18 September 2023). "Unicode request for historical asteroid symbols" (PDF). unicode.org. Unicode. Retrieved 26 September 2023.
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