q VEL AND q PUP (q Velorum and q Puppis). That's right, lower-case "q," which can make it difficult when starting a sentence. The names, q Velorum and q Puppis, were assigned by that intrepid eighteenth century explorer of the southern hemisphere, Nicholas Louis de Lacaille (1713-1762), who lettered the deep southern stars that Bayer could not see. Within constellations of his own making, Lacaille first (like Bayer) used Greek letters, then switched to Roman (but unlike Bayer, upper-case first, then lower) roughly according to brightness. When he broke the Great Ship Argo into its three parts (Vela, the Sails, Puppis, the Stern, and Carina, the Keel), the Greek letters went with them. The Alpha and Beta stars (Canopus and Miaplacidus) are in Carina, while Gamma (Regor) is in Vela. Puppis does not pick one up until Zeta (Naos). The Roman letters on the other hand are consecutive within the individual patterns, giving us q Velorum, q Puppis, and q Carinae. Of the three, at third magnitude (3.40) q Car comes in first, followed by fourth magnitude (3.85) q Vel then nearly fifth magnitude (4.45) q Pup. The first two are used in their constellations' outlines, while q Pup (in a busy part of the Milky Way four degrees northeast of second magnitude Zeta Pup) is not. Aside from their names, the three are quite unrelated, q Car a K3 giant, q Vel classed as an A2 dwarf, q Pup as a cooler A7 "giant" (but see below). At distances of 101.4 and 93.4 light years (give or take just half), the q's presented here have an interesting tale to tell. We adopt 0.06 magnitudes of interstellar dimming for the former, zero for the latter. With a temperature of 8950 Kelvin, q Vel radiates at a luminosity of 24.7 times that of the Sun, which gives it a radius 2.1 times solar, and a mass of 2.1 Suns. With a projected equatorial rotation speed of 97 kilometers per second, it takes under 2.1 days to rotate. Cognate results for q Pup are 7930 Kelvin, 10.5 solar luminosities, 1.7 solar radii, 1.7 solar mass, 121 km/s, and under 0.7 days. Both are fairly young, q Vel and Pup (theory showing it to be a dwarf) both less than halfway through their respective hydrogen-fusing lifetimes of roughly 1.0 and 1.8 billion years. Notice the sensitivity of luminosity to mass. We need only change the mass a bit (here by a factor of 1.2) and the radiant luminosity goes up 230 percent. In spite of more hydrogen "fuel," higher mass stars burn out faster than those of lower mass, the Sun from start to finish taking 10 billion years.
Written byJim Kaler 3/25/16. Return to STARS.