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HD 93129 is surrounded by the lesser stars of Trumpler 14 star cluster. Credit: NASA & ESA, Jesús Maíz Apellániz (Centro de Astrobiología, CSIC-INTA, Spain).

O stars is a lecture about an entity, source, and/or object observed using radiation astronomy that is classified as an O-type star.

You are free to take this quiz based on O stars. Once you've read and studied it, the links contained within, listed under See also, External links and the {{stars resources}} template, you should have adequate background to score 100 %.

Enjoy learning by doing!

Quiz[edit | edit source]


1 O stars can be put into classes based on?

apparent mass
spectral lines

2 Yes or No, Stellar class O stars have surface temperatures high enough that most of their luminescence is in the ultraviolet.


3 Which of the following is not a characteristic of O type stars?

can be a spectroscopic binary
the hottest stars
can be a high-velocity star
peak wavelength in the gamma-ray range
orange color.

4 True or False, Alnitak is a triple star system with an O9.7 supergiant and an O9 giant as well as a B0 giant.


5 True or False, Spectroscopically Zeta Puppis is classified as O4 I.


6 True or False, BI 253 is an O2V star in the Large Magellanic Cloud.


7 Gamma-ray stars have surface temperatures starting at 300,000,000 K (300 MK) corresponding to a peak wavelength of 0.010 nm (10 pm) for the beginning of super soft


8 True or False, X-ray stars have surface temperatures starting at 300,000 K corresponding to a peak wavelength of 10 nm for the beginning of super soft X-ray sources.


9 Which of the following is not a phenomenon usually associated with O-type SN progenitors?

a blue supergiant
an LBV
a red supergiant
an early W-R
a WN

10 Complete the text:

On the main sequence for spectral classes 06-06.5, 07, and 08 one finds strong

λ4686 absorption often accompanied by weak

λλ4634-4640-4642 emission.

11 True or False, In 1947, G. E. Kron proposed that starspots were the reason for periodic changes in brightness on blue dwarfs.


Hypotheses[edit | edit source]

  1. Stars that emit light do so because they are receiving electron irradiation.

See also[edit | edit source]

External links[edit | edit source]