Tadpoles Nebula with mysterious moving objects - please help!

[JohnSadlerAstro]

Hi,

This was exciting, keep up the "Deep-Sky Images, Ancient and Modern"

John

[gorann]

1 hour ago, JohnSadlerAstro said:

Hi,

This was exciting, keep up the "Deep-Sky Images, Ancient and Modern"

John

Thanks John!

[sulaco]

This has been one of the most interesting threads I've read, exactly the the type of thing that attracts my interest in astronomy.

Good to see an out come too, great work.

[gorann]

1 hour ago, sulaco said:

This has been one of the most interesting threads I've read, exactly the the type of thing that attracts my interest in astronomy.

Good to see an out come too, great work.

Thanks sulaco!

I have come a bit further by looking in the Washington Double Star Catalog (see screen dump) where it got two entries:

http://ad.usno.navy.mil/wds/

Here the double star has a name "LDS6184AB" and is given a "V" in the notes meaning that it is regarded as a proper binary system (bound to each other by gravity) because they move together in relation to other stars (having the same proper motion as it is called). It has been given the spectral category M3, meaning red giant, but in the images it looks to me that the companion star is smaller and blue so M3 probably only refers to the large star (or brightest) in the system. The proper motion per year of the system has been measured as +213 mas (milliarcseconds) in RA and -68 mas in Dec. Not too far from the 250 mas / year that I estimated from the photos.

I have also found out that probably 1/3 of all stars in our galaxy are binary stars (Wikipedia), so this is not a rarity, but very few show such a high proper motion as this one (when I have been overlaying POSS2 data on my RGB images I have at least not noticed that stars had moved until now). It will be fun to see what we can find out about the other moving star in the NGC1893 image, since it moves three times faster than LDS6184AB.

[beka]

On 26/02/2017 at 21:57, ollypenrice said:

Briefly back to geostationary satellites, they are geostaionary so they will produce more or less point like images on a static mount while the stars trail, but on a tracking mount they will produce trails while the stars are point-like.

Olly

Yes I guess, feels like this is something that we should have been able to figure out without having to be told :-)

[beka]

10 hours ago, gorann said:

Thanks sulaco!

I have come a bit further by looking in the Washington Double Star Catalog (see screen dump) where it got two entries:

http://ad.usno.navy.mil/wds/

Here the double star has a name "LDS6184AB" and is given a "V" in the notes meaning that it is regarded as a proper binary system (bound to each other by gravity) because they move together in relation to other stars (having the same proper motion as it is called). It has been given the spectral category M3, meaning red giant, but in the images it looks to me that the companion star is smaller and blue so M3 probably only refers to the large star (or brightest) in the system. The proper motion per year of the system has been measured as +213 mas (milliarcseconds) in RA and -68 mas in Dec. Not too far from the 250 mas / year that I estimated from the photos.

I have also found out that probably 1/3 of all stars in our galaxy are binary stars (Wikipedia), so this is not a rarity, but very few show such a high proper motion as this one (when I have been overlaying POSS2 data on my RGB images I have at least not noticed that stars had moved until now). It will be fun to see what we can find out about the other moving star in the NGC1893 image, since it moves three times faster than LDS6184AB.

Hi again Gorann, so this is what I got with your other star. It might be either number 35 or 37 in the list in the screen dump (another binary?). Both have high proper motions with the second close to your estimate. I haven't really been able to figure out the signs of the proper motions.

 

[gorann]

12 hours ago, beka said:

Hi again Gorann, so this is what I got with your other star. It might be either number 35 or 37 in the list in the screen dump (another binary?). Both have high proper motions with the second close to your estimate. I haven't really been able to figure out the signs of the proper motions.

 

Hi Beka,

Thanks for you efforts!

In the table the RA coordinate seem wrong, it should be 05 23 11 (looks like you have 080 something - but maybe I am looking at the wrong column). However, if it is the star marked with a green ring in your map then it looks correct. I just did a VizieR search and found it in the LHS catalogue, being called LHS 1759. It has precisely the right proper motion (0.752 arcs/yr - I had it at 0.75!). I will see if I can find out more about it.

[beka]

24 minutes ago, gorann said:

Hi Beka,

Thanks for you efforts!

In the table the RA coordinate seem wrong, it should be 05 23 11 (looks like you have 080 something - but maybe I am looking at the wrong column). However, if it is the star marked with a green ring in your map then it looks correct. I just did a VizieR search and found it in the LHS catalogue, being called LHS 1759. It has precisely the right proper motion (0.752 arcs/yr - I had it at 0.75!). I will see if I can find out more about it.

Yes it is a the star (actually two stars) highlighted. I searched using your coordinates but in the table the format is different from the usual HH MM SS. I checked the coversion,  so if you covert to degrees you get these values. I can only see a single star in the image but there are two marks on it corresponding to rows 35 and 37.

[gorann]

I just googled LHS 1759 and found it in the Simbad data base with another shorter name, Ross 65, a bit cooler as it is named after an astronomer who catalogued it, Frank Elmore Ross. It is designated as a High proper-motion star (Screen shot below)

https://en.wikipedia.org/wiki/Frank_Elmore_Ross

Then I found that we have been beaten by Cloudy Nights, where someone noticed this star move in 2010:

http://www.cloudynights.com/topic/256542-some-help-needed-for-identification/

[beka]

Nice work Gorann, but I am still left with a slight itch regarding the second star (row 35) on the USNO catalog list. It has  B magnitude of 21 so maybe that's why it not seen in the image? But it also has a high proper motion though not identical with the subject of this discussion.  Is this a coincidence?

[gorann]

1 minute ago, beka said:

Nice work Gorann, but I am still left with a slight itch regarding the second star (row 35) on the USNO catalog list. It has  B magnitude of 21 so maybe that's why it not seen in the image? But it also has a high proper motion though not identical with the subject of this discussion.  Is this a coincidence?

Yes, Mag 21 is probably not detected in my image or POSS2. If these two stars formed a binary system they should have the same proper motion, but it looks like that other star is moving in another direction (if I guess the columns right - I cannot see the headings in your screen dump).

[beka]

14 minutes ago, gorann said:

Yes, Mag 21 is probably not detected in my image or POSS2. If these two stars formed a binary system they should have the same proper motion, but it looks like that other star is moving in another direction (if I guess the columns right - I cannot see the headings in your screen dump).

Yes it is moving in a different direction. I am thinking if it is orbiting the other then there is a chance the  proper motion measured might not be identical - anyway overall this was a great excersise, we now know how to search the catalogs for the faintest objects! Now if I can only figure out how to get the Gigabytes of the USNO catalog on my computer to display using Cartes du Ciel...

[gorann]

3 hours ago, beka said:

Yes it is moving in a different direction. I am thinking if it is orbiting the other then there is a chance the  proper motion measured might not be identical - anyway overall this was a great excersise, we now know how to search the catalogs for the faintest objects!

Yes, Beka, this was a great learning experience - I had no idea that this could be done so relatively easily just on the net. Now we know where to start searching and I have the feeling that most stars that amateur astronomers normally catch with their cameras can be identified. It is a good idea to bookmark these sites until the next mysterious star hunt. The start is to find the coordinates. I first did it in DSS by bringing up images with known coordinates from POSS2 and then choosing smaller and smaller FOW until the star is dead in the middle. However, I think it can be easier done in the Aladin Sky Atlas (which is apparently based on POSS2).

 

To sum up, here are the most useful links we found:

The Aladin Sky Atlas:

http://aladin.u-strasbg.fr/java/nph-aladin.pl?

VizieR:

http://vizier.u-strasbg.fr/viz-bin/VizieR

DSS:

http://archive.stsci.edu/cgi-bin/dss_form?

The Washington Double Star Catalog:

http://ad.usno.navy.mil/wds/

Simbad:

http://simbad.u-strasbg.fr/simbad/