Andromeda (constellation)

Andromeda constellation
Latin name	Andromeda
Latin genitive	Andromedae
Abbreviation	And
Right ascension	22 h 57 m 22 s to  02 h 39 m 33 s
declination	+ 21 ° 40 ′ 36 ″ to  + 53 ° 11 ′ 13 ″
surface	722.278 deg² rank 19th
Completely visible	90 ° N to 34.8 ° S
Observation time for Central Europe	Partly circumpolar. Fully visible for at least 1 hour all year round. Full visibility (approx.): Reference point 50 ° 27 N, 11 ° 31 ′ E Beginning All year round Start 12 hours or all night July 1 End of 12 hours or all night November 1st The End All year round
Number of stars brighter than 3 mag	3
Brightest star (size)	Sirrah (2.06)
Meteor streams	Andromedids
Neighboring constellations ( clockwise from north )	Cassiopeia lizard Pegasus fishes triangle Perseus
swell	IAU ,
From the Uranometria by Johann Bayer .

Andromeda (from Greek Ἀνδρομέδα Androméda) is a constellation in the northern sky.

It is one of the better known constellations because it contains the closest spiral galaxy M  31, the large Andromeda nebula similar to the Milky Way .

description

The constellation as seen with the naked eye

The main stars in Andromeda form a chain of stars. Starting from the rectangle of Pegasus , the three brightest stars Sirrah (α And), Mirach (β And) and Alamak (γ And) are almost on one line.

As with other constellations, the visible stars here belong to our galaxy , they are no further than about 1300 light years away. Under favorable conditions, a faintly glowing nebula can be seen about 10 ° north of Andromedae, also known as the Andromeda Nebula . The distance to the Andromeda Nebula, the galaxy M 31, is much greater at around 2.5 million light years. ${\displaystyle \delta }$

history

Andromeda is one of the 48 classical constellations of antiquity described by Ptolemy .

It was named after Andromeda , a princess in Greek mythology .

Engraving from Johann Elert Bodes Uranographia (1801)

mythology

Andromeda, the only daughter of the Ethiopian king Cepheus (→ constellation ) and Cassiopeia (→ constellation ), was to be sacrificed to a sea monster - the whale (→ constellation ) - who had been sent out to punish her mother's vanity. Cassiopeia had claimed to be more beautiful than even the Nereids . Those so reviled turned to the sea god Poseidon , who sent a monster to devastate the coast of Cepheus' kingdom. According to an oracle, the monster could only be appeased through the sacrifice of Andromeda. When Andromeda, chained to a rock, awaited her fate, the hero Perseus appeared on the divine horse Pegasus (→ constellation ) and petrified the monster with the look of the severed Medusa head. As a reward he received Andromeda as his wife.

Another version connects the constellation with the legendary circle about the hero Heracles . Then the stars represent the Amazon queen Hippolyte , whose belt Heracles had to procure.

Celestial objects

Stars

See also: List of stars in the constellation Andromeda

B.	F.	MR	Names, other names	m	Lj	Spectral class
α	21st	15th	Sirrah , Alpheratz	2.06	97	B8 IV
β	43	337	Mirach , Merak, Al Mizar	2.07	199	M0 IIIa
γ1.2	57	603, 604	Alamak , Almach	2.26	355	K3 / B9 / B9
δ	31	165		3.27	101	K3 III
	51	464	Ypsilon Persei	3.59	174	K3 III
ο	1	8762		3.62	692	B6 III
λ	16	8961		3.81	84	G8 III
μ	37	269		3.86	136	A5 V
ζ	34	215		4.08	181	K1 IIe
υ	50	458	Titawin , Ypsilon Andromedae	4.1	44	F8 V
κ	19th	8976	Kappa Andromedae	4.15	170	B9 IV
φ	42	335		4.26	740	B6 IV + B9 V
ι	17th	8965		4.29	503	B8 V
ε	30th	163		4.34	169	G6 III
π	29	154		4.34	660	B5 V + F8 V
η	34	271		4.40	243	G8 IIIb
σ	25th	68		4.51	141	A2 V
	7th	8830		4.52	80	F0 V
ν	35	226		4.53	680	B5 V + F8 V
θ	24	63		4.61	253	A2 V
	3	8780		4.64	179	K0 III
	65	699		4.73	345	K4 III
	58	620		4.77	198	A5 IV
	8th	8860		4.82	655	M2 III
ω	48	417		4.83	92	F5 V
b	60	643		4.84	557	K4 III
ξ	46	390	Adhil	4.9	196	K0 IIIb
τ	53	477		4.96	680	B8 III
ψ	20th	9003		4.97	1310	G5 Ib + A0 V
χ	52	469		5.01	242	G8 III
	22nd	27		5.01	1007	F2 II
	41	324		5.03	196	A3
	2	8766		5.09	350	A3 V
ρ	27	82		5.16	160	F5 III
	14th	8930	Veritate	5.22	249.18	K0 III

β Andromedae is 200 light years distant red giant with thirty times the diameter of our sun . The name Mirach is of Arabic origin and means something like "the loins".

Double stars

system	m	distance
α	2.1 / 11.8
γ	2.2 / 5.0 / 5.5	9.6 ″
π	4.5 / 8.8	36 ″
56 am	5.7 / 5.9	200 ″
59	6.0 / 6.5	16.6 ″

The brightest star in Andromeda is Sirrah (α Andromedae). Originally it was assigned to the constellation Pegasus and was called δPegasi. It is a binary star system 97 light years away. The bluish-white shining main star has 110 times the luminosity of our sun. It is a variable star of the Alpha²-Canum-Venaticorum type . It is accompanied by a faint companion star of the 11th magnitude.

The Arabic names Alpheratz and Sirrah are derived from surrat al-faras and mean "the navel of the horse" (the horse means Pegasus).

γ Andromedae is a triple star system 355 light years away. The main star, shining orange, has eighty times the diameter and 2,000 times the luminosity of our sun. It is accompanied by two bluish 5th magnitude stars that are very close together. In a medium-sized telescope , the system can be resolved into two stars. There is a very nice color contrast between the yellow main star and the bluish companion stars, which cannot be separated in the telescope. The Arabic name Alamak means "desert lynx".

The system 56 And, 250 light years away, consists of two stars of the spectral classes K0 and K4. The system has a long distance of 200 arc seconds from the earth and can be recognized as a double star in binoculars .

59 And consists of two stars of the spectral classes B9 and A1. The system is 300 light years from the sun.

Variable stars

star	m	period	Type
α	2.02 to 2.06	23.19 hours	Short-term variable
λ	3.69 to 3.97	54.2 days	RS Canum Venaticorum Star
ζ	3.92 to 4.14	54.2 days	RS Canum Venaticorum Star
R.	5.8 to 15.2	409 days	Mira star
Z	7.7 to 11.3	irregular	Z-Andromedae star
QR	11.4 to 13.2	irregular	Super soft X-ray source
V428	5.13 ± 0.06	11.5 days	Semi-regular variable star

R Andromedae is a variable Mira- type star that changes its brightness over a period of 409 days. It reaches a maximum brightness of 5.8 ^m and can barely be seen with the naked eye under favorable conditions. In the minimum, its brightness drops to 15.2 ^m . A larger telescope is needed to observe it.

Messier and NGC objects

Messier (M)	NGC	other	size	Type	Surname
31	224		4 m	Galaxy	Andromeda Nebula
32	221		8th	Galaxy
110	205		8th	Galaxy
	404		10.0	Galaxy
	752		5.7	Open star cluster
	891		10	Galaxy
	7662		8.5	Planetary nebula
	7686		5.6	Open star cluster

M31 , the Andromeda Nebula, is the closest large spiral galaxy at a distance of about 2.5 million light years. It can already be seen as a misty spot with the naked eye and has probably been known since ancient times. In binoculars it appears as a long, elongated nebula. In telescopes with a larger aperture (from 15 cm), star concentrations and dark bands of dust become visible.

M32 is a smaller companion galaxy to the Andromeda Nebula. In binoculars and in the smaller telescope it appears star-shaped.

M110 is another companion galaxy to the Andromeda Nebula. It appears in binoculars and telescopes as an elongated, misty spot. It was discovered by Charles Messier in 1773 .

The open star cluster NGC 752 , 1500 light years away , was discovered by Wilhelm Herschel in 1786 . It can already be seen as a misty spot with the naked eye. In binoculars it can be easily resolved into 20 to 30 stars.

The spiral galaxy NGC 891 , 40 million light years away , was discovered by Karoline Herschel in 1783 . From the earth we see the galaxy on the edge, so that it appears as an elongated nebula. A central band of dust becomes visible in larger telescopes.

The planetary nebula NGC 7662 was discovered by Wilhelm Herschel in 1784. It is the remnant of a star about 4,000 light years away. In smaller telescopes it appears as a round, foggy spot. In a telescope with an opening of ten centimeters or more, the object appears as a “ smoke ring ”.

See also

• List of constellations

Web links

Commons : Andromeda  - collection of images, videos and audio files

• Cross reference for 66 stars in the constellation