(Pleiades - Alcyone Nebula)

from MistiSoftware Website



Object Notes:

  • Constellation: Taurus

  • Location: RA: 03h 47m 30s Dec: 24d 06m 11s Epoch 2000

  • Magnitude: 11.9

  • Type: Reflection Nebula

  • AKA: vdB 23









del Sitio Web Wikipedia



Alcíone A




Ascensión recta α

03h 47min 29.1s

Declinación δ

+24º 06’ 18’’


440 años-luz aprox.

Magnitud visual


Magnitud absoluta



1400 soles


13.000° K


8 soles


7 soles

Tipo espectral


Velocidad radial

+10,1 km/s


Alcíone o Alcyone (η Tauri / η Tau / 25 Tauri) es el nombre de la estrella más brillante del cúmulo abierto de las Pléyades en la constelación de Tauro. Su magnitud aparente es +2,85 y se encuentra a unos 440 años luz de distancia. Alcíone es el nombre de una de las siete Pléyades, hijas de Atlas y Pléyone.

Alcíone es en realidad un sistema estelar múltiple. La componente principal, Alcíone A, tiene una luminosidad de 1400 soles y una temperatura superficial de cerca de 13.000 K. Es una binaria eclipsante compuesta por dos estrellas gigantes de tipo espectral B separadas 0,031 arcsec. La gran velocidad de rotación de Alcíone A (más de 200 km/s) ha provocado que salga despedido gas desde el ecuador de la estrella y forme un disco alrededor de la misma.

En torno a Alcíone A hay tres acompañantes. Alcíone B y Alcíone C son dos estrellas blancas de tipo espectral A0 V y magnitud 8, separadas de la estrella principal 117 y 181 arcsec respectivamente. Alcíone C es una variable Delta Scuti, cuya magnitud oscila entre +8,25 y +8,30 en un período de 1,13 horas.


Alcíone D es una estrella de la secuencia principal de tipo F2 de magnitud +8,7 separada 191 arcsec de la componente A.







from Wikipedia Website



Observation data
Epoch J2000.0               Equinox J2000.0



Right ascension

03h 47m 29.1s


+24° 06' 18"

Apparent magnitude (V)



440 ly

(135 pc)

Spectral type




Other designations

η Tauri, 25 Tauri, HR 1165, HD 23630, BD+23 541, FK5 139, HIP 17702, SAO 76199, GC 4541, BDS 1875, CCDM 03474+2407



Alcyone (η Tau / η Tauri / Eta Tauri) is a star system in the constellation Taurus. It is the brightest star in the Pleiades open cluster. Alcyone is approximately 440 light years from Earth. It is named after the mythological figure Alcyone, one of the mythological Pleiades.




The primary component, Alcyone A, is a blue-white B-type giant with an apparent magnitude of +2.85. It is an eclipsing binary, and the two components have a separation of 0.031 arcseconds, or about the distance from the Sun to Jupiter.

The binary star is orbited by three companions. Alcyone B and Alcyone C are both 8th magnitude white A-type dwarfs and are separated from A by 117 and 181 arcseconds respectively. Alcyone D is a yellow-white F-type dwarf, 191 arcseconds from the primary. It has an apparent magnitude of +8.7. Alcyone C is classified as a Delta Scuti type variable star and its brightness varies from magnitude +8.25 to +8.30 over 1.13 hours.

Alcyone A has a luminosity of 1,400 times that of the Sun and a temperature of almost 13,000 K. The spectral type of B7 IIIe indicates that it is an emission star. A high rotational velocity of some 215 km/s has created a disk of gases flung into orbit around the star from its equator.

It is known as 昴宿六 (the Sixth Star of the Hairy Head) in Chinese.



External links








25 eta Tau, SAO 76199, HD 23630, magnitude 2.90, spectral type B7 IIIe.

from Alcyone Website




...the great and burning star,
Immeasurably old, immeasurably far,
Surging forth its silver flame
Through eternity...


Archibald Lampman's Alcyone


Alcyone represents in the sky the Atlantid nymph who became the mother of Hyrieus by Poseidon; but, though now the Light of the Pleiades, its mythological origin was by no means considered the most beautiful.


Riccioli wrote the word Alcione and Alcinoe, and some early manuscripts have it Altione.

The early Arabs called it Al Jauz, the Walnut; Al Jauzah or Al Wasat, the Central One; and Al Na'ir, the Bright One; all of Al Thurayya.


The later Al Achsasi added to this list Thaur al Thurayya, which, literally the Bull of the Pleiades, i.e., the Leading One, probably was a current title in his day, for his Italian contemporary Riccioli said, in his Astronomia Reformata, that the lucida "Alcinoe" was Altorich non Athorric.


Hipparchos has been supposed to allude to it in his Oxus, and Oxutatos, ths Pleiados, the Bright One, and the Brightest One, of the Pleiad.


Yet, in the face of these epithets, Ptolemy apparently did not mention it in the Syntaxis; while Baily, in his edition of Hyde's translation of Ulug Beg's Tables, affixed Flamsteed's 25 and Bayer's eta to the 32d star of Taurus, which is described as stella externa minuta vergiliarum, quae est ad lotus boreale - our Atlas.

In Babylonia it determined the 4th ecliptic constellation, Temennu, the Foundation Stone.

In India it was the junction star of the nakshatras Krittika and Rohint, and individual Amba, the Mother; while Hewitt says that in earlier Hindu literature it was Arundhati, wedded to Vashishtha, the chief of the Seven Sages, as her sisters were to the six other Rishis of Ursa Major; and that every newly married couple worshiped them on first entering their future home before they worshiped the pole-star.


He thinks this is a symbol of the prehistoric union of the northern and southern tribes of India.

We often see the assertion that our title is in no way connected with Alkuon, the Halcyon, that "symbolic or mystical bird, early identified with the Kingfisher," the ornithological Alcedo or Ceryle; so that although the myth of of the Halcyon Days, that "element and temperate time, the nurse of the beautiful Halcyon,"

When birds of calm sit brooding on the charmed wave,

is not yet understood, some of Thompson's conjectures as to its stellar aspect will be found interesting.

He writes that,

the story originally referred to some astronomical phenomenon, probably in connexion with the Pleiades, of which constellation Alcyone is the principal star.


In what appears to have been the most vigorous period of ancient astronomy (not later than 2000 B.C., but continuing long afterwards to influence legend and nomenclature) the sun rose at the vernal equinox, in conjunction with the Pleiad, in the sign Taurus:

the Pleiad is in many languages associated with bird-names... and I am inclined to take the bird on the bull's back in coins of Eretria, Dicaea, and Thurii for the associated constellation of the Pleiad... Suidas definitely asserts that the Pleiades were called Alkuones.

At the winter solstice, in the same ancient epoch, the Pleiad culminated at nightfall in mid-heaven...


This culmination, between three and four months after the heliacal rising of the Pleiad in Autumn, was, I conjecture, symbolized as the nesting of the Halcyon.


Owing to the antiquity and corruption of the legend, it is impossible to hazard more than a conjecture; but that the phenomenon was in some form an astronomic one I have no doubt.

Madler located in Alcyone the centre of the universe, but his theory has been shown to be fallacious.


There is no satisfactory reason for his conclusion, and not much more for Miss Clerke's remarks as to the probably size and distance of Alcyone - that it shines to its sister stars with eighty-there times the luster of Sirius in terrestrial skies, while its intrinsic brilliancy, as compared with that of the Sun, is 1000 times greater.


All this rests upon the extremely doubtful assumption of a parallax of 0".013 deduced from the star's proper motion.

It culminates on the 31st of December.

The three little companions, easily visible with a low-power, form a beautiful triangle 3' away from Alcyone.