天文学百科 The Astronomy Book (Big Ideas Simply Explained)
His strategy was to search for Cepheid variable stars, stars whose luminosity changes predictably, within nebulae, and to measure their distances from Earth.
Actual variable stars do exist, but Tabby's Star doesn't fit that profile, it's what's known as an F-type main-sequence star, and shouldn't behave anything like this.
实际变星确实存在, 但 Tabby's Star 不符合这种情况,它是所谓 F 型主序星, 不应该有这样行为。
天文学百科 The Astronomy Book (Big Ideas Simply Explained)
In 1609, Fabricius confirmed that Myra Cetaei was a periodic variable star, showing that, contrary to the prevailing Greek philosophy that the cosmos was unchanging, stars were not constant.
天文学百科 The Astronomy Book (Big Ideas Simply Explained)
This mainly involved measuring the brightness of stars, but a specific aspect of Leavitt's work was to identify stars that fluctuate in brightness, known as variable stars.
'I am preparing a work on variable stars. There is one of these which I have exceptionally observed for several months, and on this my great theory is mainly based.
'I have made an amazing discovery in connexion with the variable stars, ' he exclaimed. 'It will excite the whole astronomical world, and the world outside but little less.
天文学百科 The Astronomy Book (Big Ideas Simply Explained)
After 1912 Henrietta Swan Leavitt discovers a link between the period of a type of variable star and its brightness, allowing these stars to be used as standard candles for working out distances.
天文学百科 The Astronomy Book (Big Ideas Simply Explained)
Cepheid variables are reasonably easy to recognize because they are among the brightest variable stars, and they have a characteristic light curve, showing fairly rapid increases in brightness followed by a slower tailing off.