News release date: 14th January, 2005
LIRIS Observations of SN 2004ao
|J-band image (left) and NIR spectrum (right) of SN 2004ao, obtained on June
8, 2004 (t~+90 days) with LIRIS at the William Herschel Telescope. On the image, the nucleus of the
host galaxy UGC10862 is visible to the northwest of the supernova. The slit position
has been marked with a box enclosing the supernova. North is to the top and East is to the
left. On the spectrum, main features have been marked with
a vertical line. [ JPEG ]|
The spectrum of SN 2004ao shows a set of broad emission bands
superimposed on a quite flat continium, indicating that the supernova was
close to reach the nebular phase at the date of the observations.
Special attention should be paid to the P-Cygni
feature, with the absorption at λ~1.043 μm, as well as to the emission
bands at λ~0.924, 1.130 and 1.191 μm (all these wavelengths are
refered to the
host-galaxy rest frame, that corresponds to z=0.0056).
Currently, few NIR spectra of core-collapse SNe are found in the literature.
In particular, this fact is more evident for Type Ib SNe at phases older
than ~one month after maximum. This
supernova probably was a "normal" (i.e., non hyper-energetic) Type Ib supernova, despite
it was a fairly brigth object.
The SN 2004ao data recorded in this observing test show the feasibility to
programs of spectrophotometric follow-up of SNe in the NIR window with LIRIS. An article on this research for inclusion in the next issue of the ING newsletter is in preparation by Gómez, G, López, R., Acosta-Pulido, J. and Manchado, A.