Английская Википедия:EW Lacertae
Шаблон:Short description Шаблон:Starbox begin Шаблон:Starbox image Шаблон:Starbox observe Шаблон:Starbox character Шаблон:Starbox astrometry Шаблон:Starbox detail Шаблон:Starbox catalog Шаблон:Starbox reference Шаблон:Starbox end
EW Lacertae, also known as HD 217050 and HR 8731, is a star about 940 light years from the Earth, in the constellation Lacerta.[1] It is a 5th magnitude star, so it will be faintly visible to the naked eye of an observer located far from city lights. It is a Gamma Cassiopeiae variable, varying in brightness from magnitude 5.22 to 5.48, over a period of about 8.7 hours.[2] The star's variable spectrum, which shows changes on timescales ranging from hours to decades, has been monitored for more than a century.[3][4]
The spectral class of EW Lacertae has been given as B4IIIpe,[5] a hot giant star showing emission lines. Other publications have given types between B1 and B5, a luminosity class of III (giant) or IV (subgiant), and noted various spectral peculiarities related to being a shell star.[6] Models published in Gaia Data Release 3 place the star towards the end of its main sequence life.[1]
Although spectrograms of EW Lacertae, then known as Boss 5918 or BD+47°3985, had been acquired as early as 1887,[3] the existence of an envelope surrounding EW Lacertae was first noticed in a spectrogram taken in 1913.[4] Edwin Frost noted that the star's spectrum was variable, in 1919.[8] In 1943, Ralph Baldwin reported that EW Lacertae had a shell spectrum.[9] The shell spectrum had disappeared in the years 1918 - 1921, but reappeared in 1922.[10] Spectra taken in 1925, 1926 and 1928 again showed no features associated with a shell, but the shell features in the spectrum were very clear by the end of 1940.[3]
Observations in the early 1950s at the Lick Observatory by Merle Walker revealed that EW Lacertae was a variable star,[11] and it was given its variable star designation in the General Catalogue of Variable Stars.[12]
The complex variations seen in the spectrum of EW Lacertae may be caused by a disk of gas surrounding the star, seen nearly edge-on by an observer on the Earth, which occasionally has temporary density enhancements which persist for years.[13]
References
- ↑ 1,0 1,1 Ошибка цитирования Неверный тег
<ref>
; для сносокdr3
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокgcvs
не указан текст - ↑ 3,0 3,1 3,2 Ошибка цитирования Неверный тег
<ref>
; для сносокHubert1987
не указан текст - ↑ 4,0 4,1 Ошибка цитирования Неверный тег
<ref>
; для сносокVoikhanskaya1976
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокAntoniou2011
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокskiff2014
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокMAST
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокFrost1919
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокBaldwin1943
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокKogure1975
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокWalker1953
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокwalker1958
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокMon2013
не указан текст
- Английская Википедия
- Страницы с неработающими файловыми ссылками
- Lacerta
- Hipparcos objects
- Henry Draper Catalogue objects
- Durchmusterung objects
- Objects with variable star designations
- Gamma Cassiopeiae variable stars
- B-type giants
- Bright Star Catalogue objects
- Страницы, где используется шаблон "Навигационная таблица/Телепорт"
- Страницы с телепортом
- Википедия
- Статья из Википедии
- Статья из Английской Википедии
- Страницы с ошибками в примечаниях