Intro to Constellation (3) Carina

Here comes a constellation barely visible in Wisconsin: Carina.

Name: Carina

Abbr: Car

Chinese Name: 船底座

Brightest Star: Alpha Carinae / Canopus (-0.72 m)

Visibility: 20 N to 90 S, prime in March

In Latin, Carina means the keel of a ship. The constellation is one of the foundations of Ptolemy’s constellation: Argo Navis, the great ship of Jason and the Argonauts who searched for the Golden Fleece. The other two foundations of Argo Navis are Vela (the sails) and Puppis (the poop deck).

Rather close to the south celestial pole, Carina never sets for most of the southern hemisphere. But for the observers in the northern hemisphere, Carina could be difficult to find. In theory, to find Canopus, the brightest star in Carina, one needs to stay in the locations south of 37°18‘N.

From northern China, the stars of Carina can hardly be seen. Some of the stars in Carina were assigned to the Vermilion Bird of the South (南方朱雀). In the Ming dynasty, Xu Guangqi (徐光启) acquired more knowledge from western star charts and placed the rest of the stars into The Southern Asterisms (近南极星区).

Notable Stars

There are many bright and interesting stars in Carina. Let us start with Canopus.

Canopus is the second brightest star in the night sky. As a star brighter than first magnitude (-0.72m), it is visible in the early twilight. Located around 310 light-years from the Sun, Canopus is a white-hued bright giant with a luminosity 10,000 times brighter than the Sun.

Actually, Canopus has been the brightest star during three epochs over the past four million years. Sirus moved close enough to outshine it about 90,000 years ago. In 480,000 years, Canopus would regain its position (Vega is also on the way to challenge it though).

In Greek legend, Canopus was the pilot/navigator of Menelaus, the king of Sparta. In 1153, Spanish Muslim astronomer Ibn Rushd observed the star and used its different visibility in different latitudes to argue that the earth is round.

An Egyptian poet described Canopus as:

the star which pours his light in a glance of fire, when he disperses the morning dew.

老人星 闪烁如火中一瞥，驱散晨露

(Chinese Astronomy)

Canopus也即老人星，早在战国时期就有记录。在汉代，老人星曾是不详的征兆，预示了战争。而到了唐代，人们更多的用寿星，或是南极仙翁来指代老人星。就像先前提到的，由于地理位置的局限，中国古代的观星者不能很好的观测老人星。明代的徐光启借鉴了西方星图，补缺了部分空白。

Notable Systems And Objects

Eta Carinae is a prominent variable star system. There are at least two stars in the system. The primary star is 100 times as heavy as the Sun, and 5 millions times brighter than the Sun. The system is obscured by the Homunculus Nebula. With irregular eruptions, it sometimes could be very bright, reaching almost first magnitude. The primary star of the system could become a supernova in the future. Hopefully, that would not impact our earth too much.

Around the system, you can find NGC 3372, The Carina Nebula.

Credit

Most of the contents are summarized from Wikipedia. You can click the images to reach the source websites.