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Since the early 19th century, astronomers have observed this extremely long-period eclipsing binary located in the constellation Auriga, the charioteer. In 1928, astronomer Harlow Shapley correctly concluded that the two stars were about equal in mass. Based on this information they should be about equal in brightness as well. But the spectrum of the system showed no light from the companion at all. The visibly bright first star (called the primary) was being eclipsed by a massive, invisible second star (called the secondary).
Epsilon Aurigae is bright enough to be seen with the unaided eye even in the most light-polluted cities, and it is visible every fall, winter and spring. The change in brightness that this star undergoes is called an eclipse (a process of fading and coming back to its usual brightness).
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7 Comments
Add CommentI think it's more precise to describe the 'invisible' companion as a generally non-luminous obscuring mass, with no known supernatural effects.
Reply | Report Abuse | Link to thisdoes the star register in other spectrums or not at all ?
Reply | Report Abuse | Link to thisIt would seem highly unlikely that the companion is a black hole - it would have to be galactic nucleus-sized to completely occlude the primary, right? I'm not sure what else is in that neighborhood - but a several-million-solar-mass black hole would probably stick out like a sore thumb.
Reply | Report Abuse | Link to thisMaybe there's an advanced civilation around the secondary that either has a Dyson hemisphere for capturing energy from the primary during the eclipse phase, or a way of completely cloaking all output from their own home star. Yeah, that seems likely...
Dark matter? Nah, it would let the phontons from the primary right through. There'd be no eclipse phase, but all the same mechanics if it were 'dark matter'.
What other ideas have people come up with?
For it to darken in eclipse like that is a mystery.
Reply | Report Abuse | Link to thisTwo radical things that come to mind for me are perhaps an antimatter star? I would guess something that massive and giving off that much energy would have a significant signature, but it's interesting to think about.
Another would be an atmospheric haze produced by the companion star, obscuring the luminosity. Perhaps the proximity to the other star has produced some internal gravitational affect that produces a coronal fog, with the excess energy radiating in a non-visible spectrum.
Curious.
I am no expert, but my first question would be whether it emits energy in the non-visible portion of the electromagnetic spectrum, as others have suggested. This has probably already been investigated. I would also try to verify that both stars are the same or similar ages. Are there any stars in the vicinity that are much older than the bright star, suggesting some sort of collision of celestial systems that might have trapped an already collapsed black hole and a younger star in orbit? In such a scenario, the density of the collapsed older star might make it a black hole, while allowing it to retain the mass of its dance partner. Again, this is way outside my area of expertise.
Reply | Report Abuse | Link to thisIt is likely not an "antimatter star", since when the antimatter came in contact with matter, we would get very high energy readings that aren't present.
I would like to know what the spectrum looks like as it begins its fade out, and what it looks like as it reappears. Then I will make my guess.
Reply | Report Abuse | Link to thishttp://en.wikipedia.org/wiki/Epsilon_Aurigae
Reply | Report Abuse | Link to thisprovides a simpler consensus explanation not mentioned above, including reference links:
"Epsilon Aurigae is an unusual eclipsing binary system comprising an F0 supergiant and a companion which is generally accepted to be a huge dark disk orbiting an unknown object, possibly a binary system of two small B-type stars. About every 27 years, Epsilon Aurigae's brightness drops from an apparent visual magnitude of +2.92 to +3.83.[2] This dimming lasts 640–730 days.[3] In addition to this eclipse, the system also has a low amplitude pulsation with a non-consistent period of around 66 days.[4]"
The wikipedia entry also includes 2 additional artists' renderings...