Quote:
Originally Posted by Stonius
Keeping in mind I know next to nothing about spectroscopy and expect to be schooled in exactly why this is not possible in about 5 minutes time :-)
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Two words... "absolute magnitude"
If we consider that our sibling was cast out at any sort of significant velocity say 4 billion years ago (let's allow it to grow up with Sol for 500million years), at a velocity of say 20km/s (a low velocity for a cast out star), it would be about 82000 parsecs away by now...
Even at 1 billion years ago, it would be at 23000 parsecs away.
The Sun's absolute magnitude is 4.7... if our sibling is the same G-type star, it would be very very very very faint...
Trying to get a spectra of such a faint star would require many minutes, if not hours of exposure. Only a space telescope (maybe Magellan on Earth) could manage that...
Merlin, care to comment on exposure times for spectra?
OIC!