Epsilon Snakes (ε Snakes, Epsilon Serpentis, ε Serpentis , abbreviated Eps Ser, ε Sgr ) is a single [10] Am star [11] in the equatorial constellation of the Snake , the star itself belongs to the asterism “Head of the Snake” . Epsilon Snakes has a visible magnitude of +3.69 [2] , and, according to the Bortl scale , is visible to the naked eye even in the inner city sky ( Eng. Inner-city ). Although the star is designated Epsilon (5th letter of the Greek alphabet ), the star itself is the 6th brightest in the constellation.
| Epsilon Snakes; ε Snakes | |||
|---|---|---|---|
| Star | |||
   | |||
| Observational data ( Age J2000.0 ) | |||
| Type of | Am star | ||
| Right ascension | |||
| Declination | |||
| Distance | 70.4 ± 0.3 St. years (21.60 ± 0.09 pc ) [a] | ||
| Visible magnitude ( V ) | +3.69 [2] | ||
| Constellation | Snake | ||
| Astrometry | |||
| Radial velocity ( R v ) | −9.4 ± 0.6 [3] km / s | ||
| Own movement (μ) | RA: +128.19 [1] Dec: +62.16 [1] | ||
| Parallax (π) | 46.30 ± 0.19 [1] mas | ||
| Absolute magnitude (V) | +2.04 [5] | ||
| Characteristics | |||
| Spectral class | kA2hA5mA7 V [6] | ||
| Color Index ( B - V ) | +0.14 [2] | ||
| Color Index ( U - B ) | +0.12 [2] | ||
| physical characteristics | |||
| Weight | 1.820 ± 0.026 [7] M ☉ | ||
| Radius | 1,783 ± 0,040 [7] R ☉ | ||
| Age | 500 ± 200 [7] years | ||
| Temperature | 7928 ± 88 [8] K | ||
| Luminosity | 12.134 ± 0.296 [7] L ☉ | ||
| Metallicity | +0.38 [8] | ||
| Rotation | 33.1 [8] | ||
| |||
| Database Information | |||
| SIMBAD | data | ||
| Sources: [9] | |||
From parallax measurements obtained during the Hipparcos mission [1] , it is known that the star is removed at about 70.4 St. years ( 21.6 pc ) from Earth . The star is observed north of 86 ° S. w. , that is, it is visible practically on the entire territory of the inhabited Earth , with the exception of the polar regions of Antarctica . The best time to watch is May [12] .
Epsilon Snakes moves at a slightly lower speed relative to the Sun than other stars: its radial heliocentric speed: -9 km / s [3] , which is 10% less than the speed of local stars of the Galactic disk , and this also means that the star is approaching the Sun. But in the sky the star moves at a speed of almost an angular second per year to the northeast [13] . Thus, the Epsilon of the Snake appears to be a visitor from another part of the Galaxy [14] .
Content
- 1 star name
- 2 Star Properties
- 3 Nearest star surroundings
- 4 notes
- 4.1 Comments
- 4.2 Sources
- 5 Links
Star Name
Epsilon Snakes ( Latinized version of Epsilon Serpentis ) is Bayer's designation given to him by a star in 1603 [13] . The star also has a designation given by Flemstead - 37 Snakes ( lat. 37 Serpentis ) and a designation given by Gould - 29 G Sagittarius ( lat. 29 G Serpentis ) [13] .
Epsilon Snakes is a member of the Arabic asterism al-Nasak al-Yamani ( eng. Al-Nasaq al-Yamānī ), which means “Southern line” in the full asterism of al-Nasakan , which means “Two lines” [15] , along with Alpha Snakes (Uniquehai), Delta Snakes , Delta Ophiuchus (Yed Prior), Epsilon Ophiuchus (Yed Posterior), Zeta Ophiuchus and Gamma Ophiuchus [16] .
According to the abridged catalog of stars “Technical Memorandum 33-507” containing 537 star names, the names al-Nasak al-Yamani or Nasak Yamani were the names for two stars: Delta Snakes as Nasak Yamani I and Epsilon Snakes as Nasak Yamani II [17] .
In Tamil, the star is called Nulla Pambu , which means "The Good Snake" [18] .
In Chinese astronomy, the star refers to the asterism 天 市 右 垣 ( Tiān Shì Yòu Yuán ), which means “The right wall of the celestial market’s hull”, and refers to the asterism representing the eleven old kingdoms of China, which marks the right border of asterism, consisting of stars of Beta Hercules , Gamma Hercules , Kappa Hercules , Gamma Snakes , Beta Snakes , Alpha Snakes , Snake Delta , Epsilon Snakes, Ophiuchus Delta , Epsilon Ophiuchus and Zeta Ophiuchus [19] . Therefore, the name Epsilon of the Snake in Chinese is 天 市 右 垣 八 , ( Tiān Shì Yòu Yuán bā - “The Eighth Star of the Right Wall of Heavenly Market Enclosure , which represents the kingdom of Ba (巴) [20] [21] [22] .
Star Properties
Epsilon Snakes is a dwarf of the spectral class kA2hA5mA7 V [6] [b] , which indicates that the hydrogen in the star’s core serves as nuclear “fuel”, that is, the star is in the main sequence . This notation also indicates that the spectrum reflects the calcium K-line of star A2, the hydrogen lines of star A5, and the metal lines of star A7 [25] . A star emits energy from its external atmosphere at an effective temperature of about 7928 K [8] , which gives it the characteristic white-yellow color of a star of spectral class A and makes it a source of ultraviolet radiation [c] .
The mass of the star is usual for a dwarf and is 1.82 [7] . Due to the small distance to the star, its radius can be measured directly, and the first such attempt was made in 1922 . The angular size of the star was then estimated at 0.8 mas , which means that at this distance its absolute radius is equal to the radius of the Sun [26] . Subsequent measurements showed [27] [28] that its radius is more than one and a half times larger than the radius of the Sun and is 1.78 [7] . Also, the star shines much brighter than our Sun , its luminosity is 12.1 [7] . In order for a planet similar to our Earth to receive about the same amount of energy as it receives from the Sun, it would have to be placed at a distance of 3.48 a. e. , that is, approximately to where the asteroid belt is located in the solar system . Moreover, from this distance the Epsilon of the Snake would look almost 46% smaller than our Sun , as we see it from the Earth - 0.27 ° [d] (the angular diameter of our Sun is 0.5 °).
The age of the Epsilon Snake system is about 0.5 ± 0.2 billion years [7] . The star has a surface gravity of 4.346 GHS [8] or 221 82 m / s 2 , that is, slightly less than on the Sun ( 274.0 m / s 2 ), which, apparently, can be explained by the large surface of the star. The rotation speed is 33.1 km / s [8] , which gives a period of rotation of the star of the order of 2.8 days. The star itself was checked for the presence of a magnetic field , but the detected level was not statistically significant [29] . Epsilon Snake found an excess of infrared radiation at a wavelength of 25 μm , which suggests that the star is surrounded by a circumstellar disk of dust with a temperature of 250 ± 70 K , which can rotate at a distance of about 4.2 a. e. from the star [30] .
Nearest star environment
The following stellar systems are within 20 light-years [31] of the Epsilon Snake star (included only: the closest star, the brightest (<6.5 m ) and noteworthy stars). Their spectral classes are shown against the background of the colors of these classes (these colors are taken from the names of the spectral types and do not correspond to the observed colors of stars):
| Star | Spectral class | Distance, st. years |
| Alpha Snakes | K2 III | 4.32 |
| 5 snakes | F8 III-IV | 06/15 |
| 39 Snakes | G1 V | 16.47 |
Near the star, at a distance of 20 light-years , there are also about 15 red , orange dwarfs and yellow dwarfs of spectral class G, K and M, as well as 3 white dwarfs that are not on the list.
Notes
Comments
- ↑ Distance calculated by the given parallax value
- ↑ In the 20th century, Epsilon Snakes were classified as either a dwarf of the spectral class A2Vm [23] , or even as a subgiant of the spectral class A6IVm [24]
- ↑ From the Wien displacement law , the radiation energy of a completely black body is maximum at a given temperature at a wavelength of λ b = (2,898⋅10 6 nm • K) / (6813 K) ≈ 0.37 nm , which lies in the near ultraviolet part of the electromagnetic spectrum
- ↑ The angular diameter (δ) is calculated by the formula:
- where R S is the radius of the star, expressed in a. e .; d S is the distance to the star, expressed in a. e.
Sources
- ↑ 1 2 3 4 5 6 ( van .) Van Leeuwen, F. (2007), " Validation of the new Hipparcos reduction ", Astronomy and Astrophysics T. 474 (2): 653-664 , DOI 10.1051 / 0004-6361: 20078357
- ↑ 1 2 3 4 (Eng.) Feinstein, A. ( 1974 ), " Photoelectric UBVRI observations of Am stars ", Astronomical Journal T. 79: 1290 , DOI 10.1086 / 111675
- ↑ 1 2 de Bruijne, JHJ & Eilers, A.-C. ( October 2012 ), " Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project ", Astronomy & Astrophysics T. 546: 14, A61 , DOI 10.1051 / 0004-6361 / 201219219
- ↑ 1 2 3 4 Collaboration G. Gaia DR2 - 2018 .-- Vol. 1345.
- ↑ Anderson, E. & Francis, Ch. ( 2012 ), " XHIP: An extended hipparcos compilation ", Astronomy Letters T. 38 (5): 331 , DOI 10.1134 / S1063773712050015
- ↑ 1 2 (English) Gray, RO; Corbally, CJ; Garrison, RF & McFadden, MT ( July 2006 ), " Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample ", The Astronomical Journal T. 132 (1): 161– 170 , DOI 10.1086 / 504637
- ↑ 1 2 3 4 5 6 7 8 (English) Boyajian, Tabetha S .; McAlister, Harold A .; van Belle, Gerard & Gies, Douglas R. ( February 2012 ), " Stellar Diameters and Temperatures. I. Main-sequence A, F, and G Stars ", The Astrophysical Journal T. 746 (1): 101 , DOI 10.1088 / 0004-637X / 746/1/101 . See table 10.
- ↑ 1 2 3 4 5 6 (English) David, Trevor J. & Hillenbrand, Lynne A. ( 2015 ), " The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets ", The Astrophysical Journal T. 804 (2): 146 , DOI 10.1088 / 0004-637X / 804/2/146
- ↑ (English) * eps Ser - High proper-motion Star , Center de Données astronomiques de Strasbourg , < http://simbad.u-strasbg.fr/simbad/sim-id?Ident=eps+Ser > . Retrieved August 27, 2019.
- ↑ Rodriguez, David R .; Duchêne, Gaspard; Tom, Henry & Kennedy, Grant M. ( May 2015 ), " Stellar multiplicity and debris discs: an unbiased sample ", Monthly Notices of the Royal Astronomical Society T. 449 (3): 3160–3170 , DOI 10.1093 / mnras / stv483
- ↑ Adelman, Saul J. & Albayrak, Berahitdin ( October 1998 ), " Elemental abundance analyses with DAO spectrograms - XX ", Monthly Notices of the Royal Astronomical Society T. 300 (2): 359–372 , DOI 10.1046 /j.1365-8711.1998.01859.x
- ↑ HR 5892 . A catalog of bright stars .
- ↑ 1 2 3 Nulla Pambu (Epsilon Serpentis, 37 Serpentis) Star Facts . Universe Guide .
- ↑ ETA SER (Eta Serpentis ) . Jim Kaler, Stars .
- ↑ Kunitzsch, P., Smart, T. (2006), A Dictionary of Modern Star names: A Short Guide to 254 Star names and Their Derivations (Second Revised ed.), Cambridge , MA: Sky Publishing , p. . 31, ISBN 1-931559-44-9
- ↑ Allen, RH Star Names: Their Lore and Meaning . - Reprint. - New York , NY: Dover Publications Inc, 1963. - P. 243. - ISBN 0-486-21079-0 .
- ↑ Rhoads, Jack W. ( November 15, 1971 ), Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars , Jet Propulsion Laboratory , California Institute of Technology , < https: //ntrs.nasa. gov / archive / nasa / casi.ntrs.nasa.gov / 19720005197_1972005197.pdf >
- ↑ Snake summer constellation . A catalog of bright stars .
- ↑ (Chinese) 中國 星座 神話 , written by 陳久 金. Published by 台灣 書房 出版 有限公司, 2005, ISBN 978-986-7332-25-7 .
- ↑ Allen, Richard Hinckley ( 1963 ), "Serpens," Star Names , p. 376 , < http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Serpens*.html >
- ↑ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文 教育 資訊 網 2006 年 7 月 8 日
- ↑ (Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name Archived August 10, 2010 . , Hong Kong Space Museum . Accessed on line November 23, 2010.
- ↑ Epsilon Serpentis . Internet Stellar Database .
- ↑ e Serpentis . Alcyone Bright Star Catalog .
- ↑ Walker, Richard (2017), Spectral Atlas for Amateur Astronomers: A Guide to the Spectra of Astronomical Objects and Terrestrial Light Sources , Cambridge University Press , p. 116, ISBN 1316738760 , < https://books.google.com/books?id=oQQvDwAAQBAJ&pg=PA116 >
- ↑ CADARS catalog entry: recno = 6874 Catalog of Stellar Diameters (CADARS) .
- ↑ CADARS catalog entry: recno = 6875 Catalog of Stellar Diameters (CADARS) .
- ↑ CADARS catalog entry: recno = 6873 Catalog of Stellar Diameters (CADARS) .
- ↑ Shorlin, SLS; Wade, GA; Donati, J.-F. & Landstreet, JD ( September 2002 ), " A highly sensitive search for magnetic fields in B, A and F stars ", Astronomy and Astrophysics T. 392: 637–652 , DOI 10.1051 / 0004-6361: 20021192
- ↑ Smith, R. & Wyatt, MC ( June 2010 ), " Warm dusty discs: exploring the A star 24 μm debris population ", Astronomy and Astrophysics T. 515: 16, A95 , DOI 10.1051 / 0004-6361 / 200913481
- ↑ Stars within 20 light-years of Bonner Durchmusterung + 24 ° 2786: (English) . Internet Stellar Database .