BDanielMayfield wrote: ↑Fri Jan 11, 2019 3:25 am
Chris Peterson wrote: ↑Thu Jan 10, 2019 10:47 pm
BDanielMayfield wrote: ↑Thu Jan 10, 2019 7:46 pm
What are the names of the three brightest stars in today's APOD? (The yellow one on the left and the two blue stars on the right.)
Courtesy of Astrometry.net. (Upper right zeta Pup = Naos, lower right gamma2 Vel = Regor)
Thanks Chris. The yellow giant Suhail is interesting, being just under (probably) the mass needed to cause it to blow as a Supernova. Zeta Pup aka Naos is another matter however:
Ann, are ya slippin' just a little? How'd you miss this one? Surely you knew about it. You must have been short on time or something.
Zeta Puppis (ζ Puppis, abbreviated Zeta Pup, ζ Pup), also named Naos, is a star in the constellation of Puppis.
The spectral class of O4 means this is one of the hottest, and most luminous, stars visible to the naked eye. It is one of the sky's few naked-eye class O-type stars as well as one of the closest to Earth. It is a blue supergiant, one of the most luminous stars in the Milky Way. Visually it is over 10,000 times brighter than the Sun, but its high temperature means that most of its radiation is in the ultraviolet and its bolometric luminosity is over 500,000 times that of the Sun. It is also the 62nd brightest star in terms of apparent magnitude from Earth.
Naos is typical of O-type stars in having an extremely strong stellar wind, measured at 2,500 km/s, which sees the star shed more than a millionth of its mass each year, or about 10 million times that shed by the Sun over a comparable time period.
I was indeed short of time, but... guess what? This very image, this APOD (which is not a new picture) along with reviewed Hipparcos parallaxes, made me just a little disappointed in Zeta Puppis. Not that it still isn't utterly amazing. But very long story short, I used to think that Zeta Puppis was both brighter and bluer than I now believe it is.
But really, it was this particular picture, this APOD (a version of which has been published before), that clinched it for me. Which of the two stars, Zeta Puppis or Gamma Velorum, looks more impressive? I had never before seen "the difference in power" between these two stars look so striking as it does in this picture. Maybe it's just because Gamma Velorum seems to be immersed in such a huge blue reflection nebula (which isn't there: Gamma Velorum isn't sitting in a reflection nebula).
Yes, I know. Zeta Puppis is a single star, which is quite remarkable for such a massive star, which are so often multiple. Of course, Zeta Puppis is a runaway star, which is the reason for its loneliness. The same thing is true for AE Auriga, Mu Columba and Zeta Ophiuchus. Gamma Velorum, the non-runaway, is a multiple star, as you would expect. But in a way it is its binarity that makes it so special, since its brightest component is made up of one O-type supergiant and one rare Wolf Rayet star.
So yes, I was short of time, and I decided that I would talk about the star that looked most amazing here, and there could be no doubt that the star in question would be Gamma Velorum.