Extremely variable star in Orion Nebula?

So I was just about to throw out a damaged poster printout of an Orion Nebula picture from 2008 when I took a moment to compare it to a picture I had taken of the nebula in 2006. Lo and behold, there was a star present in the older photo that was not in the newer image taken with a better, more sensitive camera. My star charts don't contain enough detail to identify this star, so I'm wondering if any of the other space experts on this forum have a way of identifying it. There's actually two variable stars in this section of the image as you'll see, but one is detected in both images; it only gets brighter in the newer image. The other star nearer the center of the image vanishes from the newer image. It *might* still be there in the newer image, but if it is it really blends in with the camera's noise. I think I see it as a single pixel, but I don't think it's clear enough to call it a detection.

[atsimg]http://files.abovetopsecret.com/images/member/bef671018f94.gif[/atsimg]

The older image is the base image, and was taken on November 19, 2006 with a Meade DSI and 8" LX200. The newer image has been rotated to fit on top of the old image, and was taken on March 8, 2008 using a Canon XTi and the same LX200. Is this an eclipsing binary with a very dim companion, or is there another explanation for this star?

[edit on 24-8-2009 by ngchunter]

In b4 nibiru Have you checked astro software if there's anything supposed to be there? You might have discovered something new here.

[Edit] Also, is it possible to check in the near future if it's still there?

[edit on 24/8/2009 by PsykoOps]

Are you sure it's not just a satellite or something else? How long an exposure did you have?

I'd say the problem was using two different cameras.

Meade DSI (Deep Sky Imager)
* CCD Imager - High Sensitivity Sony Super HAD Color CCD Sensor
* Pixels - 510x492 (250,000 pixels)
* Pixel Size (in microns) - 9.6 microns (W) x 7.5 microns (H)
* A/D Conversion - 16-bit (greater depth and contrast)

Canon XTi
* 10.1 megapixel CMOS sensor with improved microlens array, fill factor and lower noise
* EOS Integrated Cleaning System
* Anti-static coatings on sensor surfaces plus anti-dust materials in the camera body
* Separate low pass filter with ultra-sonic vibration
* Software based dust mapping / removal
* Nine point Auto Focus sensor (same as EOS 30D) with F2.8 support
* Continuous shooting burst up to 27 JPEG and 10 RAW images


Because of the lower pixel quality of the Meade, a star could not show up because of dimness, being too small, not enough exposure time, etc. Due to the change in cameras (by a significant level of quality), it is hard to say if something mysteriously appeared (aka a new star). Personally, I think it is the change in quality that did it.

Originally posted by PsykoOps
In b4 nibiru

Have you checked astro software if there's anything supposed to be there? You might have discovered something new here.

[Edit] Also, is it possible to check in the near future if it's still there?

I checked with Cartes du Ciel, which has fairly detailed charts, but it doesn't show stars this dim. I have the Sky2000 and Tycho 2 catalogs loaded in Cartes. I should be able to look again in the near future since Orion is starting to rise just before sunrise, but I need it to get it up pretty well over the horizon to get a good image and resolve the dimmest stars like this one.

Originally posted by Now_Then
Are you sure it's not just a satellite or something else? How long an exposure did you have?

The exposures with the DSI were only 30 seconds long and it showed up there just fine without any noticeable streaking. I took subframes for a period of about ten minutes and it didn't move in that time frame. The exposures with the Canon two years later were at least 60 seconds long (I'd need to drag out my laptop to get my hands on the exif originals, might do that later) and do not show the star.

[edit on 24-8-2009 by ngchunter]

Originally posted by TLomon
Because of the lower pixel quality of the Meade, a star could not show up because of dimness, being too small, not enough exposure time, etc. Due to the change in cameras (by a significant level of quality), it is hard to say if something mysteriously appeared (aka a new star). Personally, I think it is the change in quality that did it.

I'd agree if it had appeared suddenly on the XTi, but it did just the opposite; it disappeared when I used the better newer camera two years later. The base image you see in the gif is the DSI image, that's where you see the star. The XTi's image is laid over most of the DSI image in the gif and the star appears to vanish in that frame.

Nice find, maybe they name it after you !!

But, could you draw in the movement from left to right, it would be easier to see !

[edit on 24/8/2009 by ChemBreather]

Originally posted by ChemBreather
Nice find, maybe they name it after you !!

Or maybe it already has a name, like Krypton.

I'm sure I'm not the first to have noticed this, and it probably already some kind of systematic name based on the kind of star that it is, but I just don't have charts detailed enough to identify it.

But, could you draw in the movement from left to right, it would be easier to see !

I'm not sure what you mean, does this help?
[atsimg]http://files.abovetopsecret.com/images/member/0efd6a3d9cf9.gif[/atsimg]


[edit on 24-8-2009 by ngchunter]

reply to post by ngchunter


Okey, I thought the object was moving from down right and up left..
Maybe it is two objects, since it is down right in the old photo and up left in the newer photo I thought that was the move path . My mistake ...

I dont have any photo programs so I cant show you what I mean ..


[edit on 24/8/2009 by ChemBreather]

reply to post by ChemBreather


I think you're seeing the other variable star I mentioned; it's in the older photo as well in the same place as the newer photo, just dimmer.

Is the star your talking about this one?

Every 27 years, this puzzling star dramatically dims before returning to its normal brightness some 2 years later. But with the 2009-2011 eclipse, astronomers hope to learn more about the phenomenon using a new resource: thousands of citizen scientists.

Astronomy.com Article

Originally posted by refuse_orders
Is the star your talking about this one?

No, that's Epsilon Aurigae, a major star in the constellation Auriga, still interesting in its own right though. If this star had a Bayer designation its name would end with "Orionis." In Orion's case, Epsilon Orionis is better known as the star Alnilam. Alnilam is one of the stars of Orion's belt; in general all stars with Bayer designations are naked eye brightness or close to it. This vanishing star is far below naked eye brightness, even in the exposure where it was visible to my telescope. It could be an eclipsing binary like Epsilon Aurigae is; it's the most normal theory imho, but if so it's companion is much dimmer compared to the primary star than Epsilon Aurigae's companion is. That's kind of interesting since they say Epsilon Aurigae's companion is already dimmer than would normally be expected. Algol, perhaps the most famous eclipsing binary star, experiences about a 1.3 magnitude change in brightness - that's more of a shift than Epsilon Aurigae, but compared to what my star appears to be doing, Algol's change is barely noticeable. Here's a before and during eclipse of Algol in the constellation Perseus:
stars.astro.illinois.edu...
stars.astro.illinois.edu...
Without a finder chart you might have some difficulty figuring out which one is Algol, even though it's the only one noticeably changing relative to the other stars.

One rarer and slightly more bizarre explanation is the idea of a cataclysmic variable star, but that's not a conclusion I want to leap to without more data. These are systems consisting of a white dwarf orbiting a larger main sequence star (K or M type) - the white dwarf strips hydrogen off of the main star until it reaches critical mass and explodes in a fusion reaction that generates a nova due to brightening by 6 to 250 times the original brightness of the system. That could make a star appear at one point in time and completely vanish at another. Depending on the specific type of cataclysmic variable, it can take days or even months to dim. The one thing that bugs me about this theory as it applies to this specific star, and one major reason I wouldn't jump to this conclusion as an explanation, is that the Orion nebula is a region of the sky where you find a ton of young stars, not the remains of old dead stars, which is what a white dwarf is. That's not to say you couldn't find a white dwarf somewhere in there, it could be many light years closer or farther away than the nebula itself, or it could just be a rare older system in the midst of younger systems. I still think the most likely explanation lies in some kind of eclipsing binary, but I'm still clueless as to this star's designation.

Wow, this ended up being a longer explanation than I planned and you probably wanted, sorry about that lol.

[edit on 26-8-2009 by ngchunter]

reply to post by ngchunter


Could it be a type of Cepheid?

I am sure you have considered that already, but honestly that seems like a plausible explanation.

reply to post by jkrog08


It's one possibility, my understanding is that there are 700 known Cepheid variables in the milky way galaxy though, so it'd be a pretty rare thing to catch one in a relatively narrow field of view by accident. In trying to find that number I stumbled across a new class of variable star I had never heard of before: Orion variable! Wikipedia has this to say:

Orion variables are variable stars which exhibit irregular and eruptive variations in their luminosity and are typically associated with diffuse nebulae. It is thought that these are young stars which will later become regular, non-variable stars on the zero-age main sequence. Brightness fluctuations can be as much as several magnitudes.

en.wikipedia.org...
The star FU orionis mentioned in the article does not match the location of the star I saw, but there are quite a few orion variables around the orion nebula region (hence the reason it was discovered there) so one of them may correspond to my star. The star V0372 Ori has coordinates that are the nearest of any orion variable I've yet found, but a look at google sky shows my star present in the hubble image of the orion nebula at coordinates offset from V0372 by about 4 arcminutes in declination and 1 arcminute in right ascension. That's a pretty significant difference if it's supposed to be the same star; according to google sky, my star's coordinates are:
RA: 5h 35m 12s
Dec: -5 30' 32"
According to the SIMBAD database, V0372 is at:
RA: 05 34 46.98
Dec: -05 34 14.6

IF, and I mean IF the very rough astrometry I performed with google sky is within 120 arcseconds (2 arcminutes) of being the correct coordinates for my star, according to the general catalogue of variable stars (containing over 28,000 known variables) it shouldn't be a variable:
www.sai.msu.su...
I just found this fascinating tool, and now my curiosity is really piqued. For those interested, the query page for this tool can be found here:
www.sai.msu.su...
I've qeued up my Canon XTI image of Orion (the newer image where the star vanishes) for some very accurate automated astrometry measurements, so I should know within a few days if those initial rough coordinates are as accurate as I think they are.

The mystery deepens...

[edit on 27-8-2009 by ngchunter]

reply to post by ngchunter


I'm a bit confused, which photo shows it brighter, the one in 2006 or 2008?
Sorry, it's early, not enough coffee yet.
Cool find though. How far away is this star? sorry again, I don't know astrology.

Originally posted by sickofitall2012
I'm a bit confused, which photo shows it brighter, the one in 2006 or 2008?
Sorry, it's early, not enough coffee yet.

The one in 2006 shows it brighter. The one taken with the new, more sensitive camera in 2008 doesn't appear show it at all (buried in background noise, if present at all).

Cool find though. How far away is this star? sorry again, I don't know astrology.

I don't know the distance since I'm still unable to identify the specific star, but the nebula it *might* be physically located in (apparent proximity from our point of view doesn't necessarily mean true proximity) is about 1,500 light years away, give or take.

[edit on 27-8-2009 by ngchunter]

Well, here's an update and an answer to the mystery. I ran my photo through some astrometry calculations and confirmed that the coordinates for my star are exactly what the rough guess based on google sky showed them to be:

RA: 5h 35m 12s
Dec: -5 30' 32"

I re-ran these coordinates through the variable star finder page I previously mentioned and discovered that it's very, very picky about the way you format the coordinates. I had previously realized that you had to eliminate all the letters and other non-numerical symbols from the coordinates, entering them in a single string RA first Dec second, but I didn't realize that hours and degrees also needed to be entered as two digits at all times. Thus 5h becomes "05" not "5." Oops. Entering the coordinates correctly produces the following result:

www.sai.msu.su...

LW Ori is at about the location I calculated for this mystery star. Exact coordinates according this info chart should be

RA: 5h 35m 12.2s
Dec: -5 30' 33"

That's really good agreement with the astrometry from my photo and the rough guess based on google sky, so that solves it for me. LW Ori it is!

Some final information based on the info page linked here, "IN" type variables do indeed correspond to Orion variables I stumbled upon earlier, believed to be young stars that will mature into stable constant stars. The additional letter "S" (forming the complete "INS" designation) indicates the presence of rapid pulsations (at least a 1 magnitude shift over just a 1 day to 10 day period). The maximum magnitude listed for this star is 14.3, so it was a dim sucker even in the older DSI image (higher magnitude numbers indicate dimmer objects in astronomy). The minimum magnitude is listed as "

reply to post by ngchunter


Cool, glad you found your answer, don't know if you were aware of these Harvard studies of variables and such in the Orion Nebula or not, but here it is:


Harvard.edu...
And this as well:

www.cup.es...

Your passion for astronomy is a great asset to ATS my friend.

There was one direct link to a GREAT Harvard paper I had bookmarked, but sadly I had to re-format my hard drive and lost it, I believe you can find anything of relevance in the first link however.







[edit on 8/27/2009 by jkrog08]