{"id":35291,"date":"2022-08-11T00:00:00","date_gmt":"2022-08-11T00:00:00","guid":{"rendered":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/?post_type=purple_issue&p=35291"},"modified":"2022-09-12T11:14:48","modified_gmt":"2022-09-12T11:14:48","slug":"star-of-the-month-12","status":"publish","type":"post","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/2022\/08\/11\/star-of-the-month-12\/","title":{"rendered":"Star of the month"},"content":{"rendered":"\n

Alderamin, the brightest star in Cepheus <\/p>\n\n

\"\"
Look for a child’s drawing of a house in the sky and you’ll spot the constellation Cepheus <\/figcaption><\/figure>\n\n

Although Cepheus represents a mythical king in the sky, the constellation is more frequently described in terms of its shape: it resembles the outline of a house formed from a square base and pointed roof. The bottom-right corner of the base (southwest corner) is mag. +2.4 Alderamin (Alpha (\u03b1) Cephei). This is one of our nearer neighbours, lying at a distance of 49 lightyears. The name Alderamin translates as \u2018the right arm\u2019. <\/p>\n\n

Alderamin is a white star of spectral class A8Vn, \u2018A8\u2019 placing it in the blue-white spectral region, closer to the white or yellow-white end. <\/p>\n\n

\u2018V\u2019 indicates it\u2019s a main sequence dwarf, the \u2018n\u2019 indicating that its spectrum contains broad absorption lines caused by a fast spinrate. With a physical size 2.5 times larger than the Sun, the spin-rate for this star is high, one rotation taking just 12 hours. This translates to a rotational velocity around 283 km\/s, compared to the Sun’s rather leisurely 2km\/s. An alternative spectral designation for Alderamin is A7V\u2013IV, which hints that it\u2019s moving off the main sequence branch and evolving into a subgiant (the \u2018IV\u2019 designation), something that happens when hydrogen fusion in a star’s core begins to wane. <\/p>\n\n

Located around 3\u02da from the North Celestial Pole, <\/p>\n\n

Alderamin was the pole star around 18,000 BC and will be again in another 5,500 years. <\/p>\n\n

Alderamin emits a similar amount of X-radiation as the Sun, something which is unexpected for an A-class star such as this. The reason is likely the rapid rotation rate which gives rise to huge convective currents within the star\u2019s interior.<\/span><\/p>\n\n

<\/p>\n\n

Photos: PETE LAWRENCE <\/p>\n","protected":false},"excerpt":{"rendered":"

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