Naos (Zeta Puppis)

A blue supergiant and the second brightest O star in the sky in terms of apparent magnitude. It is embedded in the Gum Nebula and used to be the Zeta star of Argo Navis (Jason's vessel Argos) – the Greek naos meaning "ship" – before becoming Zeta in Puppis, the Stern, after the big constellation was broken up.

Typical of its breed, Naos is blowing a fierce stellar wind, averaging 2,300 km/s and over a millionth of a solar mass a year (10 million times the rate lost by the Sun). This wind has been so well observed at wavelengths from radio wave to X-ray that it has become a major proving ground for stellar wind theorists.

Naos is a classic O-type runaway star, having been ejected at high speed (nearly 100 km/s) from its place of origin in the neighboring constellation Vela. Over the past 1 to 2 million years – much of its brief life – it has covered some 400 light-years. Such stars are invariably single and spin much faster than normal O stars: in Naos's case, at least 220 km/s at its equator (100 times the Sun's rotation speed).

visual magnitude	2.21
absolute magnitude	-5.96
spectral type	O5IAf
surface temperature	42,400 K
luminosity	790,000 L_sun
mass	59 M_sun
radius	20 R_sun
distance	1,400 light-years (430 pc)
position	R.A. 08h 03m 35.1s, Dec. -40° 00' 12"
other designations	Suhail Hadar, HR 3165, HD 66811, SAO 198752, FK5 306, CoD C-39 3939, CPD P-39 2011, HIP 39429

Related category

• NOTABLE STARS

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