Strange Star -- Can someone Explain this? Other · A. Wegdan · ... · 4 · 223 · 0

Hey Guys,

So I recently bought a ZWO ASI224MC, and was playing around with it a couple of days ago, specifically the live stacking using ASI studio.

I had the camera connected to my guide scope at that time (WO uni-Guide 32mm 120mm Focal Length) and I took this image of the Flame Nebula.

cabb0c63-35e8-4d0d-bf6c-55936f14255f.jpg

And i noticed this strange looking object in the image. Obviously all the stars are bloated and have halos, but this particular on stands out. 

3.jpg

I did plate solving on astronomy.net and here is the result.

https://nova.astrometry.net/user_images/6303669#annotated

After several hours of research I found this link: http://cdsportal.u-strasbg.fr/?target=V*%20X%20Ori

What is very odd to me is that this almost invisible star (in almost all similar pictures ), is showing up that bright and with this very peculiar halo, on this tiny aperture scope. What is even weirder is that I can see it in the live view using 1 second exposures.

I tried several times, to insure that this was due to equipment errors, but i still go the same results.

When i put a UHC filter on, the star vanished from the picture completely, which i expected due to its faintness.

Mustering all my knowledge I'm guessing this star emits a rather large amount of InfraRed ? that why its being picked up by the camera sensor?

I really can't explain it or understand it, hence I'm turning to the experts to elaborate


Regards

Hi Ahmed,

When you look at the data in SIMBAD, you will see that it's magnitudes in the IR-bands J, H, and K are pretty low and hence bright. Since the star is a broadband emitter, it will also shine bright in the near-IR wavelenghts (up to 1um), where your camera isn't completely blind (https://astronomy-imaging-camera.com/product/asi224mc). When you put the UHC filter you're likely damping the near-IR signal by an amount that you supress the signal sufficiently to be detected on the short term exposure.

For the star size and shape: keep in mind that your guide scope is basically uncorrected in chromatic aberration. Therefore, the star is completely out of focus in the wavelengths under question.

Björn

andrea tasselli:
It is indeed thus, an M-type star, very cold star that emits most of its radiation in the IR (compare the V magnitude of 13 to the J magnitude of 2.3). It also a Mira type variable which means that you might also have stumbled in one of the its brighteness peaks.

Very interesting, I will try to image it specifically using my C6 and see the result, if i can get my mount to aim properly