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trinitree88
2010-Nov-27, 06:49 PM
A red supergiant disappears wirth no help from Jimmy Hoffa http://arxiv.org/PS_cache/arxiv/pdf/1011/1011.5494v1.pdf

antoniseb
2010-Nov-27, 11:23 PM
Very nice. Getting the mass of the progenitor star is great. Having it near the low end of the predicted range, even better. It gives a hard constraint for future theoretical work.

Romanus
2010-Nov-28, 06:02 PM
Thanks for the link!

Minor question: in the appendix, some of the exposure times are listed as "20x60", "8x120", and so forth; I take it those are multiple short exposures?

trinitree88
2010-Nov-28, 07:29 PM
Thanks for the link!

Minor question: in the appendix, some of the exposure times are listed as "20x60", "8x120", and so forth; I take it those are multiple short exposures?

Romanus. I think that's standard lingo for successively finer resolution....Degrees, minutes, seconds of arc ....it's seconds with the "8X120"
minutes with .....'8X120'

ngc3314
2010-Nov-28, 07:50 PM
Romanus had it right - those are in exposure-time tables, and do mean an average of multiple shorter exposures (usually with outlier rejection to get rid of cosmic-ray events or other transient defects). Especially in IR bands from the ground, the sky foreground is so bright that longer exposures will saturate the detector, so usual practice is to build up longer total times from multiple short exposures, usually shifted in between so that residual calibration shortfalls cancel rather than reinforce in the combination.

trinitree88
2010-Nov-29, 07:32 PM
Romanus had it right - those are in exposure-time tables, and do mean an average of multiple shorter exposures (usually with outlier rejection to get rid of cosmic-ray events or other transient defects). Especially in IR bands from the ground, the sky foreground is so bright that longer exposures will saturate the detector, so usual practice is to build up longer total times from multiple short exposures, usually shifted in between so that residual calibration shortfalls cancel rather than reinforce in the combination.

3314, Thank you. I was too busy to look it up and winged it. Nice to have a pro drop by. pete

slang
2010-Nov-29, 07:59 PM
Here's another arxiv link to the paper (http://arxiv.org/abs/1011.5494v1) (PDF link top right), in case the OP cache version of the PDF expires. Nice paper for a layman, not too heavy on the jargon.

Don Alexander
2010-Dec-03, 10:34 AM
Ahhh, but if you do want more jargon, here is a second and much longer paper submitted to ApJ by a different team:

Van Dyk et al. (http://arxiv.org/pdf/1011.5873v1)

I have not read this one yet, but it seems they report on the progenitor, but not its disappearance.

Romanus
2010-Dec-05, 03:13 AM
Thanks again for the replies. :)

trinitree88
2010-Dec-28, 08:09 PM
Thanks again for the replies. :)

Romanus. Post-Xmas greetings, and you're welcome.....even to the wrong one!:shifty::doh::lol: pete