31 Lyncis
An aging giant star with the traditional name Alsciaukat.
31 Lyncis, also known by the traditional name Alsciaukat, shines as the fourth-brightest star in the constellation Lynx. This orange-hued giant is just visible to the unaided eye, with a typical apparent magnitude of +4.25. It lies roughly 380 light-years from the Sun and is drifting away at a heliocentric radial velocity of +25 km/s.
The star is an aging giant, classified as K4+ III. Its brightness varies slightly, making it a semiregular variable with the designation BN Lyncis. One 1993 study reported a brightness change of 0.05 magnitude over 25 to 30 days, while a later analysis of Hipparcos data from 2002 suggested a period of just 3.5 days. Its magnitude ranges from 4.21 down to 4.27.
At about 1.3 billion years old, 31 Lyncis has nearly double the Sun’s mass. Having exhausted the hydrogen in its core, it has swollen to 53 times the Sun’s radius. Its expanded photosphere radiates roughly 782 times the Sun’s luminosity at an effective temperature of 3,921 K.
The star’s Flamsteed designation is 31 Lyncis. It also carries the traditional names Alsciaukat—from the Arabic aš-šawkat, meaning “the thorn”—and Mabsuthat, from al-mabsūtah, “the outstretched (paw).” In 2017, the International Astronomical Union’s Working Group on Star Names officially approved Alsciaukat as the star’s proper name.
Quick Facts
- Apparent magnitude
- 4.21 to 4.27
- Spectral type
- K4+ III
- Distance
- ~380 light years
- Radial velocity
- +25 km/s
Facts from the source article.
Lore & Background
31 Lyncis bears the traditional names Alsciaukat, from Arabic الشوكة aš-šawkat meaning 'the thorn', and Mabsuthat, from Arabic المبسوطة al-mabsūtah meaning 'the outstretched (paw)'. The International Astronomical Union approved the name Alsciaukat for this star on 30 June 2017. It also has the variable star designation BN Lyncis, as it is classified as a semiregular variable with brightness ranging from 4.21 to as low as 4.27. A 1993 study found that it varied in brightness by 0.05 magnitude over 25 to 30 days, while a 2002 study of Hipparcos data found a period of 3.5 days.
Reader's Guide
31 Lyncis is an aging giant star that has exhausted the hydrogen supply at its core and expanded to 53 times the Sun's radius. It radiates about 782 times the Sun's luminosity from its swollen photosphere at an effective temperature of 3,921 K. The star is 1.3 billion years old with almost double the mass of the Sun. Its variability was studied in two separate investigations that produced differing periods—one suggesting 25 to 30 days, the other 3.5 days—leaving the star's exact pulsation behavior unresolved. As the fourth-brightest star in Lynx, it serves as a notable reference point in the constellation. Its traditional name Alsciaukat, meaning 'the thorn', reflects its Arabic heritage, and the star is also known by the variable star designation BN Lyncis. The star's Flamsteed designation is 31 Lyncis.
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