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M45
(Pleiades - Alcyone
Nebula)
from
MistiSoftware Website
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Object Notes:
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Alcíone
del Sitio Web
Wikipedia
Alcíone A
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Constelación
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Tauro |
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Ascensión recta α
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03h 47min
29.1s |
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Declinación δ
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+24º 06’
18’’ |
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Distancia
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440 años-luz aprox. |
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Magnitud visual
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+2,85
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Magnitud absoluta
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-2,41
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Luminosidad
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1400 soles
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Temperatura
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13.000° K
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Radio
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8 soles
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Masa
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7 soles
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Tipo espectral
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B7 IIIe
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Velocidad radial
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+10,1 km/s
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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.
Referencias
Alcyone
from
Wikipedia Website
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Observation data
Epoch J2000.0 Equinox J2000.0
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Constellation |
Taurus |
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Right ascension |
03h 47m 29.1s |
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Declination |
+24° 06' 18" |
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Apparent magnitude
(V) |
+2.85 |
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Distance |
440 ly
(135 pc) |
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Spectral type |
B7IIIe+A0V+A0V+F2V |
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Other designations |
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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.
Description
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
Alcyone
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...
Alcyone!
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.
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