A desperate battle

Stellar name
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A desperate battle , i.e Taurus alpha (Alpha Tauri, abbreviated as α Tau), the 14th bright star in the sky [16] , Average Apparent magnitude 0.85 etc( Irregular variable star , varying from 0.75-0.95, etc.), Absolute magnitude -0.64, its spectral and photometric classification is K5 III, orange, surface temperature three thousand and nine hundred Kelvin It is 65 light-years away from the earth. [1]
Chinese name
A desperate battle
Foreign name
Aldebaran
Alias
Taurus alpha
Classification
Red Giant
Quality
About 1.16 M ⊙
surface temperature
About 3900 K
Apparent magnitude
0.85 etc
Absolute magnitude
About -0.641, etc
Rotation period
~520 d
Right ascension
4:35:55.24
Declination
+16°30′33.49″
Distance from ground
About 65.3 light years
Radius
44.13±0.84 R☉
Spectrum type
K5+III
radial velocity
54.26±0.03 km/s
Parallax
49.97±0.75 mas
Surface gravity
1.45±0.3
Luminosity
439±17 L☉
Amount of metal
-0.33±0.1 dex
Autorotation speed
3.5±1.5 km/s
U − B color index
one point nine two
B − V color index
one point four four

Star name

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The Western Traditional Name of Aldebaran Aldebaran , from Arabic "Al Dabar  n" means "follower", because it always follows Pleiades Appears after. In 2016, International Astronomical Union The working group approved that the proper name of Aldebaran is“ Aldebaran "。
Aldebaran is Taurus The brightest star in the Taurus alpha (α Tauri); The Froude name is sorted according to the right ascension position, and the name is about Apparent magnitude The name of a star above grade 7 is Taurus 87 stay Bright star list The number of is HR one thousand four hundred and fifty-seven , in HD catalog HD 29139 Hipparcos catalogue In is HIP 21421 Most of these names appear only in scientific publications.
It also appears in Variable star catalogue Top, listed as one Variable star However, it is only marked by Bayer name, and there is no exclusive variable star name.
Aldebaran and several nearby stars are also listed in the binary catalog. For example, WDS 04359+1631 in the Washington Binary Catalog and ADS 3321 in the Aiken Binary Catalog. It is also included in William Herschel The double star catalog H IV 66, and the Stewart double star catalog Σ II 2, and Burnham Double Star Master List 14 companion stars β 550 are listed. [2]

Observation history

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On March 11, 509 Greece Athens Observed Moon Shelter Aldebaran. British astronomer edmond halley The time of this event was studied, and in 1718, it was concluded that Aldebaran must have changed its position and moved a few minutes of arc to the north since that time. This and observing other stars, Sirius And Arcturus, leading to their own discovery. It is observed that in the past 2000 years, the position of Aldebaran has changed by 7 ', which is equivalent to one fourth of the diameter of the full moon [3] because precession of the equinoxes , 5000 years ago Vernal equinox Near Aldebaran.
On March 9, 1497, Copernicus I made a famous observation with Maria. That night, the night was clear, the stars were shining, and a crescent moon floated in space. They stood on the tower of St. Joseph's Church and observed the bright star "Aldebaran" of "Taurus" to see how it was gradually moved closer Crescent moon Concealed. When Aldebaran meets the moon and there are still some gaps, Aldebaran soon disappears. They accurately measured the time when the "Aldebaran" disappeared, calculated firm data, and proved that those gaps were part of the moon's eclipse. The "Aldebaran" was hidden by the shadow of the moon itself, and the size of the moon did not shrink. That's it Copernicus Ptolemy Of Geocentric theory A gap was opened.
British astronomer William Herschel In 1782, it was found that Aldebaran had a dim companion star, 117 "away from Aldebaran, with an apparent magnitude of only 11 degrees [4] This companion star was proved by Burnham to be a close couple in 1888 Konductra And found a 14 degree companion star 31 "from Aldebaran Self exercise The measurements of Herschel's companion star and Aldebaran are divergent, and there is no physical correlation between them. However, the self motion of the companion star discovered by Burnham is almost the same as that of Aldebaran, which indicates that the two formed a loose conjunction system.
In 1864, William Huggins Private in Tulsen Hill, England observatory The first spectral study of Aldebaran was carried out. In the spectrum, he distinguished the spectral lines of nine elements, including iron, sodium, calcium and magnesium. In 1886, Harvard University Observatory Edward of· Pickering use Photographic plate 50 were captured in the spectrum of Aldebaran Absorption line This was published in 1890 Henry Draper Catalogue Part of. By 1887, photography technology had been improved Doppler shift Astrometric radial velocity In this way, Potsdam Herman Karl of the Observatory· Vogel And his assistant Julius Scherner to measure and estimate the Retrogression speed Is 48 km/s. [5]
In 1921, Mount Wilson Observatory Use the Interferometer To measure it Angular diameter However, this measurement did not solve this problem. [6]
Aldebaran has a wide observation history, so it was selected Gaia mission 33 reference stars used to calibrate and derive star parameters [7] It was also used to calibrate Hubble Space telescope Instrument on. [8]

Observation method

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Aldebaran is one of the most easily found stars in the night sky, largely because of its brightness. Follow Orion The three stars in the belt, the first bright star encountered in the opposite direction to Sirius, is Aldebaran.
Aldebaran is only on Earth with Bistar cluster In the direction of line of sight, so it looks like Open cluster A member of the Hyades cluster, and the brightest star in the cluster. In fact, the Hyades cluster is about 150 light-years away, much farther than Aldebaran's 65 light-years away.
Aldebaran is located in zodiac Within Ecliptic surface 5.47 degrees to the south. Therefore, it can be covered by the moon. When the moon Ascending intersection near Autumnal equinox This will happen Occultation event. From January 29, 2015 to September 3, 2018, a total of 49 times of lunar occultation occurred [9] Each event has only Northern Hemisphere Or near the equator, Australia or South Africa The area is too far south from the zodiac to see Aldebaran obscured by the moon. On September 22, 1978, the diameter of Aldebaran was measured accurately in the event of the moon covering Aldebaran. [10]
June 1 every year A desperate battle meeting close Day.

Physical characteristics

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The spectral type of Aldebaran is K5+Ⅲ, which shows that it is a giant star. After exhausting the hydrogen in the core Herotu Of Main sequence star Evolve. The center of the star collapses into Degeneracy And ignited the hydrogen in the core shell, making the current Aldebaran Red Giant Branch (RGB).
Aldebaran photosphere Effective temperature Is 3900 K, and the surface gravity is 1.59 cgs; It is 25 times lower than the gravity of the earth and 700 times lower than the sun, but it is a typical giant star. Its metal content is 30% lower than that of the sun.
Ibaku satellite And other sources, and surrounding environment Its distance from the earth is 65.3 light years (20.0 Second gap )。 Astroseismology Has determined its mass ratio The sun is about 16% larger. However, due to the expansion of its radius, its brightness is Solar luminosity 439 times. Aldebaran Angular diameter already Measured Many times, as part of Gaia benchmark calibration, the value used is 20.58 ± 0.03 mas [8] The diameter of Aldebaran is about 62.8 million kilometers, 45.1 times the diameter of the sun.
Aldebaran is an unobvious variable star, which is classified as "LB" type Slow irregular variable Variable star catalogue Display its luminosity at Apparent magnitude 0.75 to 0.95, etc. Modern research shows that the amplitude is small, sometimes almost unchanged. Hipparcos Photometric measurement The display amplitude is only 0.02, and the possible period is about 18 days [11] Dense ground-based photometric measurements show variations as high as 0.03, and the period may be 91 days. It is found from long-term observation and analysis that, Total amplitude It may still be less than 0.1, and the total change is considered irregular.
The photosphere shows that there are a lot of carbon, oxygen and nitrogen, which indicates that this giant star has gone through the first upturn stage - this is the evolution of the star Red Giant During which matter from deep within the star is brought to the surface by convection [12] Aldebaran lacks generation due to slow rotation Corona Generator required, therefore not Hard X-ray The source of the launch. However, due to the convective turbulence near the surface, Lower atmosphere It may still exist small scale Magnetic field. Measured Tara magnetic field intensity 0.22 gauss [13] Although in Stellar spectrum Detected in ultraviolet rays Emission from this area Soft X-ray It could be because Chromosphere And weakened. Aldebaran is taking 30 km s −1 Speed, (1 – 1.6) × 10 −11 M⊙ yr −1 (About one every 30000 years Earth mass )Rate of loss of mass [12] This constant Stellar wind It may be caused by weak magnetic field in the lower atmosphere.
In Aldebaran Chromosphere Above the layer, there is an extended MOLsphere, where the temperature is low enough to form gas molecules. This region is about 2.5 times the radius of the star, and the temperature is about 1500 K. Spectral display carbon monoxide , water and titanium oxide [12] Outside the MOLsphere, the stellar wind continues to blow outward until it reaches Terminal shock wave Boundary, thermal, ionization Interstellar matter It forms a boundary with Aldebaran as the center and a radius of about 1000 Astronomical unit Of Star wind bubble , and become one led by Aldebaran Local bubble

Planetary system

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1993 Arcturus and Beihe III Of radial velocity The measurement shows that Aldebaran has long period The image speed oscillates, which can be interpreted as secondary companion To Aldebaran Track survey , meaning at a distance of 2.0 AU (300 G meters) and Eccentricity On a small orbit, there is one with a mass of at least 11.4 times Jupiter Mass companion star with 643 days Orbital period work. However, the three observed stars all exhibit similar oscillations, producing companion stars of similar mass. Therefore, the author concludes that this change may be caused by the inherent star rather than the gravity of the companion star. [14]
In 2015, a study showed that there was evidence of long-term stability in the activities of planets and stars [15] Astroseismology Analysis of planet fitting residual It is determined that Aldebaran has a planet with the lowest mass of 5.8 ± 0.7 times the mass of Jupiter.
Aldebaran's planetary system
member
AU
(d)
radius
2056±168 M⊕
1.46±0.27
628.96±0.9
0.1±0.05
-
-
(References: [15]

Aerospace information

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United States Aerospace Nobody in the bureau spacecraft Pioneer 10 , leave solar system Later, it will move towards Taurus. If there is no accident, this spaceship will approach Aldebaran in 2 million years.