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A "new" binary?

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#1 3c_273

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Posted 14 September 2013 - 08:33 AM

Last night, a front blew through, and my urban (white zone) skies were exceptionally transparent. I managed to glimpse the nucleus of NGC 891, a galaxy that heretofore had been invisible from Little Tycho.

It was not a good night for double stars, so I observed variables instead. When I did an estimate of RZ Per, I noticed a pair of 10mv stars that did not have a WDS designation. The stars are in the UCAC4 listed as:

706-011096, 022.6006527, +51.1648573
706-011101, 022.6068245, +51.1642987

Note that both the RA and Dec are in decimal degrees. Here's a more traditional position, that you can drop into Aladin or WikiSky:

01:30:24.16 +51:09:53.5

The pair has an estimated separation of 22", and a position angle of 97 degrees.

I'm attaching a copy of the DSS plate of the double.

After 200+ years of serious double star study, one would think that ALL pairs brighter than 17mv and wider than 1" would have been cataloged, yet when I look at the WDS, the stars aren't there:

01303-2932LDS2203 1955 2000 2 130 131 175.0 175.7 17.2 17.5 -051-053 013021.43-293206.9
01303-7517UC 569 1998 1998 2 130 130 12.8 13.0 10.5 16.0 -067-053 -063-053 V 013016.24-751709.6
01304+0748PLQ 17 1891 2003 13 337 336 5.7 6.4 9.69 10.47 G5 +027-010 +024-008 +07 223 013026.14+074826.7
01304+6614MLR 118AB 1895 2003 13 91 89 8.3 7.1 8.09 12.19 K3III +003-009 +001-009 +65 173 L 013025.03+661425.4
01304+6614MLR 118AC 1971 2003 8 135 133 22.0 21.0 8.09 11.6 +003-009 U 013025.03+661425.4
01304-1846B 653 1926 1986 4 132 134 1.6 2.0 9.96 12.5 G0V +034+021 -19 258 013022.98-184539.2
01304-1903ARA 518 1916 1916 1 39 39 11.4 11.4 10.7 12.5 +007-008 -19 261 X 013023.08-190321.5
01304-2612BU 1230 1891 1959 8 225 226 2.6 3.0 6.0 11.0 K4III +050+001 -26 502 013022.88-261228.3
01305+0258A 2318 1911 1991 5 154 156 3.5 3.6 8.98 12.57 F5 -002+013 +000+008 +02 221 013029.14+025816.4

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#2 Cotts

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Posted 14 September 2013 - 10:30 AM

Hi, Tom. Looks like you're onto something here. I found the double marked as a double in my Millennium Star Atlas with little difficulty. So it is in somebody's double star catalog. But whose?

Not the WDS.

Putting the coordinates in SIMBAD the two stars of the pair are as follows:
Primary BD +50 291p at 01 30 23.56 +51 09 46.1
Secondary BD +50 291s at 01 30 25.4 +51 09 44.1

Each star in the pair has other designations like TYC and so on but it does not have a WDS identifier. SIMBAD would definitely give the WDS # if it existed.

By the way, your quoted WDS list is way off. It shows WDS identifiers like 00131+3521 (to pick one) which is 00h 13m .. If your pair were in the WDS it would be 01306+5110. . Decimal places.....

The fact that the BD numbers for your pair have 'p' and 's' suffixes (standing for 'primary' and 'secondary') means that the pair is known.

I think you should drop a note to Brian Mason at the USNO and announce your discovery to him. You could be published!

Dave

#3 WRAK

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Posted 14 September 2013 - 12:07 PM

Separation is according to Stellarium about 15 arcsecs. Have you checked proper motions? If different, then this is no binary - if yes good chance to get an WDS entgry.
Wilfried

#4 3c_273

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Posted 14 September 2013 - 03:12 PM

Now that you've have had a look at this, I'll send it over to the USNO.

Many thanks for your quick and accurate reviews.

David,

The WDS listing I originally posted was indeed incorrect. Thanks for the catch! The last digit of the WDS Id Right ascension is the decimal minutes, so for 24", I would expect that to read as 4, not 6. I've replaced my original listing with the present one, where the pair is also not shown.

Then again, the Aladin reading of the UCAC4 stars indicates that the stars are at 22.6 degrees of right ascension. The WDS uses sidereal hours. Wouldn't it be nice if astronomy had consistent units and everything was MKS? Yep, and the pigs are taxiing down the runway for takeoff...

Wilfried,

According to the UCAC4, the proper motions of both members of the pair are identical. Thanks for pointing out proper motion, as it indicates that this is indeed a physical pair. My 22" separation came from subtracting the RAs of both stars and multiplying by 15.

#5 Ed Wiley

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Posted 14 September 2013 - 07:18 PM

You should write it up for JDSO if not on any catalog. Good find, not many of those around.

Ed

#6 Cotts

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Posted 14 September 2013 - 08:15 PM

You should write it up for JDSO if not on any catalog. Good find, not many of those around.

Ed


Hmmmm. Co-author, anyone????? :poke:

Dave

#7 fred1871

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Posted 14 September 2013 - 09:36 PM

Tom, yes, send it to Brian Mason and see what response you get. That the star is marked double on an Atlas etc etc shows it's not unknown, merely missed from WDS.

The question is why it's not in WDS. I had the experience, mid-1990s, when I was in California and working my way through far-northern doubles, of finding two doubles that were readily visible in my C8 but were not listed in the WDS at the time. Somewhat later they were listed there - they'd apparently dropped out by accident, as both had discovery dates in the 1800s, as I'd expect with doubles not especially faint or difficult.

You might be luckier with your find. Who knows? :grin:

#8 Ed Wiley

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Posted 15 September 2013 - 10:53 AM

Dave, good thought -- since you see it as double in an atlas, chances are that its already discovered by someone. If Brian spends any of his time running this one down, I would advise Tom to offer him a coauthor slot if publication worthy.

Ed

#9 Cotts

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Posted 16 September 2013 - 08:40 AM

Actually, Ed, I was thinking of myself (and the 5 minutes it took me to look it up in SIMBAD). That sort of effort has gotta be worth at least a cup of coffee.... :grin:

Dave

#10 3c_273

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Posted 16 September 2013 - 03:52 PM

Dave,

I just heard back from Bill Hartkopf, and he's confirmed the discovery. I think he'd be interested in the catalog you found it in:

william.hartkopf@usno.navy.mil

I probably will write a short article about it, and you and Wilfried will be mentioned!

#11 Cotts

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Posted 17 September 2013 - 09:34 AM

Dave,

I just heard back from Bill Hartkopf, and he's confirmed the discovery. I think he'd be interested in the catalog you found it in:

william.hartkopf@usno.navy.mil

I probably will write a short article about it, and you and Wilfried will be mentioned!


TVB 1 has a nice ring to it, eh? Start writing, mon ami. With 30 years of proof reading experience I would be glad to check it over if you wish.

Dave

#12 Ed Wiley

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Posted 17 September 2013 - 05:53 PM

Actually, Ed, I was thinking of myself (and the 5 minutes it took me to look it up in SIMBAD). That sort of effort has gotta be worth at least a cup of coffee.... :grin:

Dave


Actually, Dave, I was hoping you would save yourself for a paper with me. Are you game? We can talk it over at Okie-Tex. I have some ideas..........

Ed

#13 Cotts

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Posted 17 September 2013 - 06:20 PM

Sure I'm game. What sort of thing do you have in mind?

Dave

#14 Ed Wiley

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Posted 18 September 2013 - 07:49 PM

Dave:

We can talk a bit more at Okie-Tex. One thought: Review some of the Herschel doubles, find the ones with common proper motions, measure, and then look at relative motion. First step is the measures. Game?

Ed

Ed

#15 Cotts

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Posted 18 September 2013 - 10:29 PM

OK. Sounds like a good chat over coffee..

I just did some more imaging with the TEC. See thread in Double stars here. Will post in a few minutes....

Dave

#16 darren8se

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Posted 04 October 2013 - 02:37 PM

Awesome so you found a bonifide new double ? Congrats !!
Great work i bet its rare as hens teeth to find a new binary system these days ?






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