Intro to Constellation (1) Boötes

Well, if you have checked out my front page, you may notice that I mention stargazing as my hobby. Actually, I only know few constellation. Stargazing to me is literally gazing at stars. To learn more about the night sky, I decide to read the Wiki pages of the 88 constellations listed by the IAU (Internation Astronomical Union). But I would not write posts for all of them. I will include some of the interesting ones.

Let’s start with Boötes.

Name: Boötes

Abbr: Boo

Chinese Name: 牧夫座

Brightest Star: Alpha Boötis / Arcturus (-0.04 m)

Visibility: 90 N to 50 S, prime in June

Boötes, the Herdsman, is a constellation in the northern sky. There are many bright stars within the constellation, 29 of which are visible to the naked eye.

Ancient Babylonians depicted Boötes as Enlil, the leader of the pantheon and the special patron of farmers. In the eyes of ancient Egyptians, Boötes resembled the foreleg of an ox. Nowadays, people view the pattern of stars as a kite or an ice cream cone.

Notable Stars

Arcturus or Alpha Boötis is the brightest star in the constellation. It’s also the brightest star in the northern celestial hemishpere. The latinised name Arcturus means “Guardian of the Bear” in ancient Greek. Since the star is associated with the Ursa Major mythology (I will introduce that story in a later post).

Located at 36.7 light year from the Sun, Arcturus is a red giant with roughly the same mass of our sun but 170 times as luminous. One can find the star by following the arc of the handle of the Big Dipper.

(Chinese Astronomy)

在中国天文学中，这是大角星，北天球最亮的星。它代表着青龙的角，同时也是角宿中最亮的星，故名大角。它有着重要的地位，因为它的位置能够表明新一轮阴历的开始。我们可以先找到北斗七星的弧形勺柄，然后画延长线来找它，下次试试 :)。

Notable Systems And Objects

There are quite a few multiple stars in Boötes. Epsilon Boötis is a triple star that attracts many amateur astronomers. The primary is an oranged-hued gaint star, the secondary is a blue-hued main-sequence star, the tertiary is a rather faint star. In a telescope, the color will be very colorful.

As a side note, main-sequence stars refer to a band of stars that appears on plots of stellar color versus brightness. These plots are known as Hertzsprung–Russell diagrams. In the figure below, counting from the bottom, the second curve stands for the main-sequence stars. The Sun is considered to be a main-sequence star.

Extrasolar planets are always fascinating. So far, astronomers have discovered 10 stars in Boötes that have planets. Among them, Tau Boötis is orbited by a large planet. Its sole planet Tau Boötis b has a mass of 5.95 Jupiter mass and an orbit distance 0.046 AU (1 AU is roughly the same as the distance between the Sun and the Earth). With the small distance, Tau Boötis b has an orbital period of 3.31 days. Planets with this type of pattern are called ‘hot Jupiter’. Remark: That speed is crazy.

As for deep-sky objects, Boötes is in a part of the celestial sphere facing away from the plane of the Milky Way. Thus, few open clusters and nebulae can be found. But there are two bright galaxies, NGC 5248 amd NGC 5676. Both of them are spiral galaxies. The image of NGC 5248 is taken by Hubble Space Telescope, whereas Sloan Digital Sky Survey provides the image of NGC 5676. So, there are some differences in resolution.

Meteor Showers

Boötes is the home to the famous Quadrantid meteor shower. The meteors are dim but have a high peak visible hourly rate. You may see 100 meteors per hour on January 3 to January 4. However, its low radiant (around keppa Boötis in the northern Boötes) and often increment weather may disappoint you. This year (2023), I did not have the chance to see it due to the overcast weather and frigid temperature.

Credit

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