ISO-SWS H2 SURVEY - RESULTS AND PRESS RELEASES
the detection of molecular hydrogen in the disk of NGC 891
Optical photograph of NGC 891 thanks to Blair Savage, Chris Howk (U.
Wisconsin)/N.A.Sharp (NOAO)/AURA/NSF
ISO-SWS data from Valentijn and van der Werf / SRON
A true colour photograph of the edge-on Spiral galaxy
NGC 891 (field of
view is 6.7 x 6.7 arcminutes). The dark band running through the center
of the disk is caused by the effect of large dust clouds in this
galaxy. At 8 positions in this disk, even beyond the field of this
photo, the
ISO-SWS has detected the signal from molecular hydrogen gas (H2). The
graphical inset shows the signal of the H2 lines at 17.0 and 28.2
micrometer wavelength, detected at the outermost position of the
survey,
at a distance 12 kilo parsec (37000 light-years) from the center, a
position where other observations of lines of molecules, like the CO
molecule, are trailing into the noise. From the ratio of the signal
strength of these lines a Temperature of the gas of about 80K is
derived. This gas has never been seen before, is quite massive and
provides, at least for this galaxy, a solution to the missing mass
problem.
Press release by Space Research Organization Netherlands
ISO satelliet detecteert signaal van ontbrekende materie
SRON
press release in Dutch
further links:
electronic publication by the Astrophysical Journal, 522, L29,
September 1, 1999
1580 x 1580 8-bit color TIFF image
full size tiff image can be down-loaded
more
down-loadable colour photographs of NGC 891 can be found here
First extra galactic detection of pure rotational
H2 lines at 17.0
and 28.2 micrometer wavelength in the center of the nearby galaxy NGC
6946 The photograph on the left is taken from the ESA press release on
Early
results of the ISO satellite., 14 February 1996
................Optical + SWS (Valentijn et
al)................................................ ISOCAM (Malhotra et
al)..................
ISOPHOT (Tuffs et al) ....................
Postscript (gzipped) versions of related papers
( PREPRINTS and REPRINTS)
- Discovery paper:
First extra-galactic direct detection of large scale Molecular
Hydrogen
in the disk of NGC 891
E.A. Valentijn and P.P. van der Werf
1999, Astrophysical Journal Letters, 522, L29
download postscript version of paper
download postscript-gzipped version of
paper
- Early report on molecular hydrogen survey in the
disks of NGC 891 and NGC 6946, presented at ESA conference
'The Universe as seen by ISO', October 1998 Paris.
The ISO-SWS Survey for Molecular
Hydrogen in Galaxies
E.A. Valentijn and P.P. van der Werf
1999, Proceedings of the Conference "The Universe as seen by ISO",
Paris, France, 20-23 October 1998 (ESA SP-427, March 1999) Edts P.Cox,
M.F. Kessler,
- Discovery paper: First extra galactic detection
of rotational lines at 17 and 28 micrometer wavelength in the center of
the nearby galaxy NGC 6946
The SWS survey for rotational H2
lines
in late-type galaxies. Observations of the central regions of
NGC6946
Valentijn, Edwin A., Van der Werf, Paul P., De Graauw, Th.,
& De Jong, T.
1996, Astron. & Astrophys. 315, L145
- Technical Paper: improving the sensitivity of
the ISO-SWS by removing the various effects of cosmic ray impacts
(cosmic weather)- self calibration techniques
ISO's Short Wavelength spectrometer
- Ultimate sensitivity
E.A. Valentijn and W.F.Thi
1999, Experimental Astronomy in press
- Technical paper: characterizing the wavelength
calibration and the spectral resolution
of the ISO-SWS.
The wavelength calibration and
resolution of the SWS
Valentijn, E.A., Feuchtgruber, H., Kester, D.J.M., Roelfsema,
P.R., Barr,
P., Bauer, O.H., Beintema, D.A., Boxhoorn, D.R., Graauw, Th.de, Haser,
L.N.,
Heske, A., Heras, A.M., Katterloher, R.O., Lahuis, F., Lutz, D., Leech,
K.J., Morris, P.W., Salama, A., Schaeidt, S.G., Spoon, H.W.W.,
Vandenbussche, B., Wieprecht, E., Luinge, W., Wildeman, K.J.
1996, Astron. Astrophys. 315, L60