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Feb
19
reviewed Approve Are black holes really singularities?
Jan
8
awarded  Popular Question
Oct
18
comment How well can we in principle determine $T_{\textrm{eff}}$ of a star?
Which is indeed most peculiar and nice, I suppose your visit has something to do with the coming PhD defence there. Will gladly continue the discussion in person!
Oct
18
comment How well can we in principle determine $T_{\textrm{eff}}$ of a star?
Yes, it is a very good point, that there also important systematic contributions. Still, again, the question really is about the magnitudes of the most relevant perturbing effects. Ideally, I would like to see a statement of the kind (this is made up): "For solar-like stars it doesn't make sense to talk about Teff up to precision better than 50K, because the convection causes a variability in the recovered Teff on the scales of a few hours."
Oct
18
comment How well can we in principle determine $T_{\textrm{eff}}$ of a star?
And more precisely, I would ideally like to know the number. Is 1K precision meaningless, or is it meaningless to talk about Teff already at precision of 100K, or... ?
Oct
18
comment How well can we in principle determine $T_{\textrm{eff}}$ of a star?
Dear Rob, I completely agree with your point, it is not possible to give one unique value for the stellar temperature, for indeed there are various kinds of imperfections going on: inhomogenieties, non-LTE, temperature variation over the photosphere, stellar variability, you name it. However, with the present spectroscopy/stellar models the precision is such that these problems above may be typically omitted as non-significant. The question I am asking then is relatively well defined: until what precision in temperature measurements is it still meaningful to talk about stellar temperature.
Oct
15
reviewed Approve What is projected separation and how can I make sense of its unit (h^-1 kpc)?
Oct
15
comment Two species of dark matter?
yes - certainly so. It hasn't been confirmed, there is only some indirect non-robust evidence for it from observations/experiment (inflation, DM, neutrino masses ..). Theoretically it has been used a lot though, e.g. in ads-cft.
Oct
14
awarded  Nice Question
Sep
26
awarded  Yearling
Aug
21
awarded  Taxonomist
Apr
19
awarded  Popular Question
Apr
7
awarded  Nice Question
Jan
28
awarded  Good Question
Jan
6
comment What is the temperature of an accretion disc surrounding a supermassive black hole?
Yes, like something you can on page 9 of your reference.
Jan
6
comment What is the temperature of an accretion disc surrounding a supermassive black hole?
I imagine, it would be more interesting to see this equation in number form.
Nov
2
awarded  Nice Answer
Oct
10
awarded  Nice Question
Oct
6
reviewed Approve What scientific evidence is there to support or refute the Iron Sun Hypothesis?
Oct
3
awarded  Custodian