This
remarkable object in Aquila dominated the professional scene two decades
ago when radio and X-ray observations linked it to a mag 13 star with an
emission spectrum that [at high resolution] changed on a daily basis. This
was attributed to jets of material ejected from the poles of a neutron
star at a quarter the velocity of light - the jets describing circles in
the sky over 164 days - hence the 'lawn sprinkler' description. From our
viewpoint the Doppler shifted velocities appear lower but nevertheless
show strong red and blue-shifted components of Ha
etc. in addition to such lines at 'rest'. Due to 'time dilation' [time
is 'slowed down' or stretched when observing an object moving at high velocity
relative to light speed] there remains a net bias towards a redshift of
12,000km/s. SS433 is also known as supernova remnant W50 and variable star
V1343Aql with period of 13days [m13.0 -15.3] with its companion star. An
excellent article - The Bizarre Spectrum
of SS433 - by Bruce Margon is in Scientific American - Oct '80.
2004 Aug 14/19: Revisit after 4 years to SS433 with LX200+MX9 CCD in 5m exposure - compare to ST7e image at bottom of page-1999 Aug 27. Spectrum in 15m exp via same scope with grating interposed - trace via AstroArt - note the absence of blue radiation in comparison to d Aql [F-type].
2000
Nov 12: revisit to SS433 after 14 month via the MX9 CCD + Rainbow
grating in brief exposures with Altair [aAql]
and Nova Aql 2[99] = V1494Aql for comparison. SS433 continues
to show strong Ha at rest wavelength 656.3nm
with a possible weak red shifted Ha line - marked.
[2000 Dec 19 - the strong blue shifted line proves to be the real
image of a faint field star !]. Blue continuum is absent due to interstellar
absorption and the unfiltered real image [zero order] of the star is typically
orange [thus ~R magnitude] making the star, estimated from images at ~m12.5
ie brighter than visual estimates. Note the dominating OIII
line in Nova Aql 2[99]
spectrum.
1999 Sept 3/4: More spectra this time via SX MX9 CCD which gives a lower resolution, wider field and slightly different spectra response to ST-7e camera. SS433 emission lines obvious in 60 sec exposures. Still the absence of flux in blue/violet.
1999 Sept 2: Further spectrograms essentially comfirm initial results with particular reference to broadened Ha and separate sideband bluewards. Approximate blue [13,000km/s] and red [8,000km/s] Doppler shift velocities shown as well as H-alpha 'rest' position of 6563A.
1999 August 27-30 : My own modest spectroscopic observations over several evenings using the Rainbow 'filter' [transmission grating ~20mm from CCD surface] amazingly record a current blue-shifted component [blue arrow/bar] in addition to a strong H-alpha at 'rest'. Curiously the SS433 spectrograms seem to show a consistant absence of flux in the violet/blue region below ~500nm and a red/IR excess. Compare with the stars immediately above SS433 [boxed] with a 'normal' continuum from ~400nm - 900nm with due allowance for each star's real image [zero order spectrum] offset to the left.
