05/06/2020
OT Gem.
OT Gem is a Be-Star which is well known since many years. More detailed data on this object can be found in the SIMBAD data base.
We will put more common information about Be-Stars also here.
Recently we observed OT Gem in four consecutive nights, results are shown in the gallery below. On the left side are the Hα observations performed on April 2nd, 2020 and April 05th, 2020 - on the right side the Hß observations performed on March 28th, 2020 and April 04th, 2020. Essential observation parameters are summarized in the table below.
OT Gem shows strong emission in Hα with a double peak structure. There was no visible change between the two observations which were taken three days before.
We think that the feature on the right side @ 659nm is driven by telluric water lines. It seems that the humidity on April 05th, 2020 was much higher. We think that there is a second feature @ 655,5nm that essentially influences the shape of the Hα structure at the blue end and to a certain extend the hight of the blue side of the double peak structure of Hα. The change of the hight within the blue side of the double peak structure might be driven by change in humidity between both observations. For future observations we have to track these values. Potentially we can try to model for telluric waterlines in order to correct such kind of effects.
The profile for Hβ shows up different. We can see a clear absorption of the line, filled with a nice double peaked emission. Similary to the double peak structure as we see in Hα. It seems that the features @ wavelengths of 490,3nm and 488,5nm on April 04th, 2020 are caused by telluric effects. At 492,2nm a significant absorption performed by He I can be identified. It's currently not understood why we see a telluric feature on March 28th, 2020 at 490,3nm and on 488,5nm on April 04th, 2020.
| March 28th, 2020 | April 2nd, 2020 | April 04th, 2020 | April 05th, 2020 | |
| Instrument | 20 Inch, Newton & LHiRes III | 20 Inch, Newton & LHiRes III | 20 Inch, Newton & LHiRes III | 20 Inch, Newton & LHiRes III |
| Slit & Grid | 23µ & 2400lines / mm | 23µ & 2400lines / mm | 23µ & 2400lines / mm | 23µ & 2400lines / mm |
| Exposure | 1 x 1200s | 3 x 1200s | 5 x 1200s | 2 x 1200s |
| Lines | H-Beta | H-Alpha | H-Beta | H-Alpha |
More images
