Affiliation
American Association of Variable Star Observers (AAVSO)
Tue, 10/15/2013 - 19:25
There is conflicting info in the literature regarding whether this object is within our own galaxy or is in M31. In fact, it has an M31 V002 designation as well. Would it not be useful to order a spectrogram by a large telescope, to determine its red-shift, and settle this matter?
Mike LMK
Hi Mike,
M31 is too close for cosmological red shift, so that won't settle the question. In fact M31 and our galaxy are moving closer together, not further away. Spectroscopy may well be useful, but not through red shift. Cheers,
Mark
[quote=Mark Blackford]
M31 is too close for cosmological red shift, so that won't settle the question. In fact M31 and our galaxy are moving closer together, not further away. Spectroscopy may well be useful, but not through red shift. Cheers,
[/quote]
Well, there must be some difference (at least theoretically) in approach/recession velocity for an object in M31 vs. one in our own galaxy. I guess the issue is whether spectroscopy has the sensitivity to tell them apart, for small shifts (vs. large cosmological ones)?
I took a look at a sky image of the variable relative to M31, and attached it here. Now, I realize that images generally do not show the true outer limit extents of galaxies well, but the location of LS And seems way too far out from the plane of M31 to be a member? I may be wrong, but this seems like its within our galaxy.
Mike LMK
Is there more known about the nova outburst in 1971? Assuming it had a max of 11.7B I doubt it very much it would lay in M31. The maximum would be fainter I suppose?
With a range of 8 - 9 mag. this one is a good RN candidate.
One more thing, the 183 star on the f-chart is a little brighter, I would say 180. Can there be a revision of the chart?
Eddy
The amplitude and duration of the outburst (see light curve in http://www.konkoly.hu/cgi-bin/IBVS?1331) suggest this is a WZ Sge type dwarf nova in our Galaxy.
Patrick
Many thanks Patrick! This one is certainly worth following!
Cheers,
Eddy
[quote=Mark Blackford]
M31 is too close for cosmological red shift, so that won't settle the question. In fact M31 and our galaxy are moving closer together, not further away. Spectroscopy may well be useful, but not through red shift.
[/quote]
Upon further research, M31 has an approach velocity of 300 km/s which is a red shift of z=-.001, which is substantially larger than shifts of objects within our own galaxy. This corresponds to a 5A shift in the visible band, and I think is well within the range of present spectroscopy technology measuring techniques. I think one good spectrum would resolve this issue.
Mike LMK