The O-Type Star α Cam


My own observations were obtained with the Littrow slit spectrograph LHiRes3 directly attached to the Meade 16-inch Schmidt-Cassegrain at the Volkssternwarte Neumarkt and later on with the LHiRes3 on a C11 SC at the Dahamm Observatory in my garden. A friend contributes echelle spectra made with an eShel fiber coupled to a C14 SC.

The echelle spectra are ranging from around 4250&8239;Å to 7000 Å with a constant resolution slightly over 10,000. The Littrow spectra are 150 Å wide snippets with an resolution of 12,000 at Hα decreasing with decreasing wave length.

Our first three spectra date from 2017.

The region at Hα

Up to March 30 in 2022 we gathered 40 echelle spectra and 60 long slit spectra covering the Hα region. It comes out that α Cam is highly variable at Hα. The shape of the H-α mountains is rapidly fluctuating. We see the spectra variing within only three hours. So it's for the birds to take spectra half a month apart.

In March 2022 we managed to get 21 spectra with Hα. See this animated gif.

H alpha from April 2022
The fluctuating Hα mountains seen in March 2022. Velocity scale is centered at 6562.79 Å. The left broad absorption at -1520 km/s is HeII6527(Ebbets, 1980) the right sharper line at 2300 km/s is the diffuse interstellar band at 6614ïÅ(Ch. C. M. Marshall, et al., 2015) originated from molecular carbon.
Cycle of an observation

First align the mount with earth's rotational axis connect everything and position the focused target star on the slit. See more details in the technical section.

The image section starts with focusing the spectrograph with the help of the build in neon lamp.

Object Type Exposuretime Number
Neon Lamp msecs to secs 1
ThAr Lamp secs 1
Star Science 600sec max 3
Thar Lamp secs 1
Flat LED Flat secs 30
Bias Bias 0.001 30
Neon Lamp msecs to secs 1

Object Type and Exposuretime are written to the header of each image file.

Last modified: 2022 May 28