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Zeta (ζ) Puppis

Shim1Pel.gif (799 bytes)z PuppisShim1Pel.gif (799 bytes)Bayer designation (1603)Shim1Pel.gif (799 bytes)
Shim1Pel.gif (799 bytes)HR 3165Shim1Pel.gif (799 bytes)Harvard Revised Photometry designation (1879+)Shim1Pel.gif (799 bytes)
Shim1Pel.gif (799 bytes)HD 66811Shim1Pel.gif (799 bytes)Henry Draper Catalogue (1918+)Shim1Pel.gif (799 bytes)
Shim1Pel.gif (799 bytes)SAO 198752Shim1Pel.gif (799 bytes)Smithsonian Astrophysical Observatory (1966+)Shim1Pel.gif (799 bytes)
Shim1Pel.gif (799 bytes)39429Shim1Pel.gif (799 bytes)Hipparcos catalogue (1997)Shim1Pel.gif (799 bytes)


Single star; early Of-type supergiant, MK type O4I(n)f; located in Puppis; R.A. 08:03:35.052, dec. -40:00:11.64; culmination early March; magnitude 2.25; distance 429 pc (approx 1400 light years).


Zeta Puppis is one of the best studied O-type stars; several important parameters have been determined with good accuracy, including the distance 352 (429) 549 pc (~1400 light years); diameter 20 R; effective temperature 42,000 ± 1500 K; and period of rotation ~4.8 – 5.2 days (Howarth et al. 1995, Schaerer et al. 1997).

Most books will say that the star is commonly known as “Naos” but I have never heard anyone, astronomer or layman, use the name.


The spectral type is certainly early O: Ochsenbien et al. 1988 published a value of O5Iaf; the earlier value of O4I(n)f derived by Walborn 1972 is preferred by Howarth et al. 1995 (table 1) and also by Schaerer et al. 1997.

Mass loss is typical for hot luminous stars. For Zeta Puppis a mass loss rate was determined from radio data by Lamers and Leitherer and rescaled by Schaerer et al. (1997) to reflect their revised distance estimate, yielding log M-dot = -5.57 ± 0.15.

Zeta Puppis possibly belongs to the young Vela R2 association of stars (Sahu 1992, Schaerer et al. 1997).

Precession in RA21.100 
Precession in dec.-103.000 
Proper Motion RA-0.031Includes cos(dec) term.
Proper Motion dec0.011 
Radial Velocity-24.0 km/s 
Parallax2.330.51 masSchaerer et al. 1997
Distance429 pcSchaerer et al. 1997
Mv-6.06calculated with d=460 pc
M*/M 59Lamers & Cassinelli 1999
L*/L 740,000
log L/L = 5.74 (5.87) 6.02, Schaerer et al. 1997
Lamers & Cassinelli 1999
Spectral TypeO4I(n)f
Howarth et al. 1995
Ochsenbien et al. 1988
14 (16.3) 21.7
Howarth et al. 1995
Schaerer et al. 1997
Lamers & Cassinelli 1999
Teff30,700 ± 2500 K
42,000 ± 1500 K
Böhm-Vitense 1989a
Howarth et al. 1995
Lamers & Cassinelli 1999
Rotational Velocity211.000 km/sHowarth et al. 1995
Period4.8-5.2 daysHowarth et al. 1995
Table 1: Known Parameters for Zeta Puppis. (After Ochsenbein & Halbwachs 1987 except where otherwise noted.)




z Puppis is located in Puppis, the largest of the four constellations established in the 1750s, when Nicolas Louis de Lacaille divided up the ancient constellation of Argo Navis. As a consequence of this history, there is no α, β, etc. Puppis; at magnitude ~2.3, z is the brightest star in the constellation, and easily found with any star chart. Alternatively, if you think about the “false cross” as an approximate mirror image of the real cross, z Puppis is the more distant of the two mirrored pointer stars.


A brilliant blue-white star, easily seen with the naked eye or any optical aid.


Böhm-Vitense, E. 1989a: Introduction to Stellar Astrophysics. Volume 1 – Basic Stellar Observations and Data. Cambridge University Press.

Howarth, I.D.; Prinja, R.K.; Massa, D. 1995: The IUE MEGA Campaign: The Rotationally Modulated Wind of ζ Puppis. Astrophysical Journal 452: L65-L68.

Lamers, H.J.G.L.M.; Cassinelli, J.P. 1999: Introduction to stellar winds. Cambridge University Press.

Ochsenbein F.; Halbwachs J.L. 1987: Le Catalogue des Etoiles les Plus Brillantes (Catalogue of the Brightest Stars). Bull. Inform. CDS 32, 83. NASA Astronomical Data Centre, catalogue 5053A.

Ochsenbien, F.; Acker, A.; Legrand, E.; Poncelet, J.M.; Thuet-Fleck, E. 1988: Le catalogue des etoiles les plus brilliantes. NASA Astronomical Data Centre, catalogue 5053.

Sahu M.S. 1992: A Study of the ISM in Puppis-Vela Including the Gum Nebula. PhD thesis, University of Groningen, The Netherlands.

Schaerer, D.; Schmutz, W.; Grenon, M. 1997: Fundamental Stellar Parameters of ζ Pup and γ2 Vel from HIPPARCOS Data. Astrophysical Journal Letters 484: L153-L156.

Walborn, N.R. 1972: Spectral classification of OB stars in both hemispheres and the absolute-magnitude calibration. Astrophysical Journal 77 (4): 312-318.

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