Ara (constellation)

Ara

Constellation
List of stars in Ara
Abbreviation	Ara[1]
Genitive	Arae[1]
Pronunciation	/ˈɛərə/, genitive /ˈɛəriː/[lower-alpha 1]
Symbolism	the Altar[1]
Right ascension	16^h 34^m 16.9497^s–18^h 10^m 41.3407^s[2]
Declination	−45.4859734°–−67.6905823°[2]
Family	Hercules
Area	237 sq. deg. (63rd)
Main stars	8[1]
Bayer/Flamsteed stars	17
Stars with planets	7
Stars brighter than 3.00^m	2
Stars within 10.00 pc (32.62 ly)	3
Brightest star	β Ara (2.84^m)
Nearest star	Gliese 674 (14.80 ly, 4.54 pc)
Messier objects	0
Meteor showers	None
Bordering constellations	Corona Australis Scorpius Norma Triangulum Australe Apus Pavo Telescopium
Visible at latitudes between +25° and −90°. Best visible at 21:00 (9 p.m.) during the month of July.

Ara is a southern constellation situated between Scorpius and Triangulum Australe. Its Latin name is Latin for "altar". Ara was one of the 48 Greek constellations described by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations defined by the International Astronomical Union.

Notable features

The constellation Ara as it can be seen by the naked eye.

Stars

Ara contains part of the Milky Way to the south of Scorpius and thus has rich star fields.^[1]

• α Ara is a blue-white hued star of magnitude 2.8, 242 light-years from Earth.^[1]
• β Ara is an orange-hued supergiant of magnitude 2.8, 600 light-years from Earth.^[1]
• γ Ara is a blue-hued supergiant of magnitude 3.3, 1140 light-years from Earth.^[1]
• δ Ara is a blue-white hued star of magnitude 3.6, 187 light-years from Earth.^[1]
• ζ Ara is an orange-hued giant of magnitude 3.1, 574 light-years from Earth.^[1]

Deep-sky objects

The northwest corner of Ara is crossed by the galactic plane of the Milky Way and contains several open clusters (notably NGC 6200) and diffuse nebulae (including the bright cluster/nebula pair NGC 6188 and NGC 6193). The brightest of the globular clusters, sixth magnitude NGC 6397, lies at a distance of just 6,500 light-years (6.1×10¹⁶ km), making it one of the closest globular cluster to the solar system.^[3]

Ara also contains Westerlund 1, a super star cluster that contains the red supergiant Westerlund 1-26, one of the largest stars known.

Although Ara lies close to the heart of the Milky Way, two spiral galaxies (NGC 6215 and NGC 6221) are visible near star η Arae.^[3]

Open clusters

• NGC 6193 is an open cluster containing approximately 30 stars with an overall magnitude of 5.0 and a size of 0.25 square degrees, about half the size of the full Moon. It is approximately 4200 light-years from Earth. It has one bright member, a double star with a blue-white hued primary of magnitude 5.6 and a secondary of magnitude 6.9. NGC 6193 is surrounded by NGC 6188, a faint nebula only normally visible in long-exposure photographs.^[1]
• NGC 6200
• NGC 6204
• NGC 6208
• NGC 6250
• NGC 6253
• IC 4651

Globular clusters

• NGC 6352
• NGC 6362
• NGC 6397 is a globular cluster with an overall magnitude of 6.0; it is visible to the naked eye under exceptionally dark skies and is normally visible in binoculars. It is a fairly close globular cluster, at a distance of 10,500 light-years.^[1]

Planetary Nebulae

• The Stingray Nebula (Hen 3-1357), the youngest known planetary nebula as of 2010, formed in Ara; the light from its formation was first observable around 1987.
• NGC 6326. A planetary nebula that might have a binary system at its center.

Illustrations

Johann Elert Bode's illustration of Ara, from his Uranographia (1801)

In illustrations, Ara is usually depicted as an altar with its smoke 'rising' southward.^[4] However, depictions of Ara often vary in their details. In the early days of printing, a 1482 woodcut of Gaius Julius Hyginus's classic Poeticon Astronomicon depicts the altar as surrounded by demons.^[5] Johann Bayer in 1603 depicted Ara as an altar with burning incense; the flames rise southward as in most atlases. Hyginus also depicted Ara as an altar with burning incense, though his Ara featured devils on either side of the flames. However, Willem Blaeu, a Dutch uranographer active in the 16th and 17th centuries, drew Ara as an altar designed for sacrifice, with a burning animal offering. Unlike most depictions, the smoke from Blaeu's Ara rises northward, represented by Alpha Arae. A more unusual depiction of Ara comes from Aratus, a Greek uranographer, in 270 BCE. He drew Ara as a lighthouse, where Alpha. Beta, Epsilon, and Zeta Arae represent the base, and Eta Arae represents the flames at the lighthouse's light.^[6]

Mythology

In ancient Greek mythology, Ara was identified as the altar where the gods first made offerings and formed an alliance before defeating the Titans.^[1] The nearby Milky Way represents the smoke rising from the offerings on the altar.^[7]

Equivalents

In Chinese astronomy, the stars of the constellation Ara lie within The Azure Dragon of the East (東方青龍, Dōng Fāng Qīng Lóng).^[8] Five stars of Ara formed Guī (龜), a tortoise, while another three formed Chǔ (杵), a pestle.

Namesakes

USS Ara (AK-136) was a United States Navy Crater class cargo ship named after the constellation.

See also

• Ara (Chinese astronomy)

References

1. Random House Dictionary

1. Ridpath & Tirion 2001, pp. 82–83.
2. "Ara, constellation boundary". The Constellations (International Astronomical Union). Retrieved 14 February 2014.
3. Dunlop 2005.
4. Ridpath, Star Tales Ara.
5. Kanas, Nick (2012). History, Artistry, and Cartography (Second ed.). Chichester, U.K.: Praxis Publishing. p. 136. ISBN 978-1-4614-0916-8.
6. Staal 1988, p. 230.
7. Staal 1988, p. 229.
8. AEEA 2006.

Bibliography

• Dunlop, Storm (2005). Atlas of the Night Sky. Collins. ISBN 978-0-00-717223-8.
• Ridpath, Ian; Tirion, Wil (2001). Stars and Planets Guide. Princeton University Press. ISBN 978-0-691-08913-3.
• Ridpath, Ian; Tirion, Wil (2007). Stars and Planets Guide (4th ed.). Princeton University Press. ISBN 978-0-691-13556-4.
• Staal, Julius D.W. (1988). The New Patterns in the Sky. McDonald and Woodward Publishing Company. ISBN 978-0-939923-04-5.

Online sources

• "AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 1 日" (in Chinese). 2006. Retrieved 10 July 2012.
• Ridpath, Ian. "Ara". Star Tales. Retrieved 7 June 2012.

External links

• The Deep Photographic Guide to the Constellations: Ara
• Star Tales – Ara
• Ara Constellation at Constellation Guide
• Warburg Institute Iconographic Database (over 150 medieval and early modern images of Ara)

Coordinates: 17^h 23^m 24^s, −53° 34′ 48″