Double Star of the Month: Gamma Leporis
AKA: H 6 40
Position: 05 hr 44 min 28 sec -22 degrees 26 min 54 sec
Due south at 20:00 (GMT) on 15 February 2023
[Double Star for Feb 2023 - #1]
Gamma Leporis
Image credit: Jeremy Perez (http://www.perezmedia.net/beltofvenus)
Used with permission
Gamma Leporis was first observed by William Herschel on 21 February 1781 and given the catalogue entry H VI 40, but he observed it again eight months later on 22 October of that year and catalogued it as H V 50. But the separations are different; V (or 5 to use modern terminology) implies a separation of 30-60 arcseconds whereas V (or 6) is a separation of more than an arcminute. H VI 40 is clearly the main double, which has a primary of magnitude 3.6 and a secondary of 6.3, with a separation of 95.5 (practically the same as in Herschel’s time). The third member of this triple is very faint (11.4) and currently has a separation of 112 arcseconds, but in Herschel’s time it was only 40 arcseconds and hence V. It is shown in the above chart but must be very difficult to observe in a small telescope. This faint star is not physically connected to the main pair which form a binary. It is very close to us, being only 29 light years away. The primary is a main sequence F6 star which is 1.2 larger than our Sun and is a relatively young 1.3 billion years old. The secondary is a cooler and smaller K3 star. As its spectral type indicates, the primary is usually seen as yellow, but because of the contrast effect, the secondary is seen as blue, green or even brick-red rather than orange. Gamma Leporis is easily located as the lower of the two stars behind the bright pair Arneb and Nihal.