Return to Home Page
>The RXTE X-ray lightcurve of Eta Car through April 25 is available at > >http://lheawww.gsfc.nasa.gov/users/corcoran/eta_car/etacar_rxte_lightcurve/ > >The rate increased by about 2.4 cts/s over the previous day's observation See, what did I tell you, Mike? ;-) If I remember correctly we had gone through the same debate exactly 5.5-yrs ago. Just to avoid being fooled by Eta again, a better precursor of the precipitous decline (after the REAL maximum) is the measure of column density. So far the change in flux is dictated by the change in emission measure. But after the X-ray maximum, there will be an unmistakably strong change in the softer end (2 -- 4 keV) of Eta's X-ray spectrum. At least that was the case in the last cycle if I remember correctly. # Column desity: for those who are not familiar with this term... # This quantity is a cumulative number of proton particle found # in between the object and Earth per unit area. Think of it as # a measure of optical depth, with significant energy/wavelength # dependence. Cheers, Bish -- "Bish" K. Ishibashi, Ph.D. Massachusetts Institute of Technology Center for Space Research e bish@space.mit.edu 77 Massachusetts Ave. NE80-6011 w 617 452 5122 Cambridge, MA 02139 f 617 253 8084
Return to the Powerful Daisaku Nogami
vsnet-adm@kusastro.kyoto-u.ac.jp
