Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Cygnus X-1 and Eta Carinae

  1. Dec 5, 2006 #1
    i keep hearing about these stars, the first one i hear is a black hole next to a blue giant i think it was, and the second was one of the most massive stars to exist.
    Can someone explain to me whats happening at Cygnus X-1 (AND!) what could happen if Eta Carinae exploded (whats this i hear about hypernovae - is it just theory or is there proof for one?)
  2. jcsd
  3. Dec 6, 2006 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Cygnus X-1 is a an X-ray source unlike other X-ray sources discovered. Most X-ray sources come from neutron stars which slowly accrete material from an orbiting star onto their magnetic poles and become very hot emitting lots of x-rays and radiation of other wavelengths and pulsars. These X-rays pulse because the neutron star is spinning and the beam is highly directional. The X-rays from Cygnus X-1 however flicker randomly on very short timescales. Because the timescales are so short it gives us a limit on the size of the object which is less than ~3000Km. The companion to Cygnus X-1 is a supergiant star which are not renound for emitting X-rays so the the X-ray source was determined to be in orbit. Furthermore its mass was said to be of the order of 7 solar masses due to the doppler shift of the companion stars spectrum. For something of seven solar masses that is not visible means that it is highly likely to be a black hole as it is too massive for a neutron star or white dwarf in current models.

    As far as Hypernovae are concerned, I was always told tey were just unusually energetic supernovae giving rise to massive gamma ray bursts. For Eta Carinae at 120-150 solar masses I suppose its a candidate for a hypernovae but perhaps somebody else should clarify this.
  4. Dec 6, 2006 #3

    "Eddington luminosity (sometimes also called the Eddington limit) is the largest luminosity that can pass through a layer of gas in hydrostatic equilibrium, supposing spherical symmetry. Using the mass-luminosity relation, it can be used to set limits on the maximum mass of a star."

    this limit is about 100 solar masses yes? i also read that we have NEVER seen the surface of the star, only the gas ejection that surrounds it now, so perhaps it is more than one star? Is it possible for mutiple stars to be clouded like that so that we can't see it? I think that happens in nebulas.
    Look at the pistol star and LBV 1806-20, these are also stars that exceed the Eddington limit, so would they travel the same path?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook