Help!!!

I think I'v discovred a 13-th magnitude companion to a 10th magnitude red dwarve in Cepheus!!!

I first discoverd a double star near Beta Cephei back in summer 2008, made up of a pair of 7.9 and 9.3 mag stars. Now, looking at that POSS images containing this double... I found one other binary only 4 arc minute to the north. Plese take one sec to look this one here:

In search of new binaries of the northern sky - by A. Ahad

Has anybody here photographd this region of Cepheus please?

Lunator (Ian) is the man to speak to when it comes to these sort of things.

But by looking at the two photo's seperated by 40+ years in certainly looks like a the comapnion star is either in front or behind it's parent star.

Sorry I cannot be of much help. But Ian will be along soon I'm sure.

wow! cool if you did. I am watching this thread with intetrest.

Hi Abdul

I have had a look at your site and you make an interesting case.

I have checked the information on the Aladin database and it is does raise some questions about this pair.

The proper motion of the pair is certainly very similar and this does imply the pair may be at least from a common origin and in a moving stream.

I also looked at the distance modulus for the pair. The secodary is at 245ly (75 parsecs) if the G5 spectral class is correct then the using the distance modulus puts the secondary at around 70-74 parsecs so reasonable close.

The information that conflicts with this is the parallax for the secondary. the parallax is 42.20 mas with a fairly large error 13 mas. If we take the smallest parallax of 29 mas this puts the secondary at 34 parsecs or 122ly.

This parallax conflicts with the spectral type as to fit with the distance modulus the spectral class would need to be around K3.

If you go to the washington double star catalogue Washington Double Star Catalog - Current Version

you can contact Brian Mason. I usually published my analysis via the Webb society Contact and I am sure Bob Argyle will be happy to review your findings.

It may be worth waiting for the publication of the UCAC3 & the New Hipparcus data as this has reworked the proper motion & parallax for thousands of stars.

I hope this helps.

Cheers

Ian

Thank you so much Ian, I have e-maild Bob Argyll for some advice.
I have previosly e-mailed Dr. Brian Mason but he said it is rare for them to accept new stars into the WDS catalog unless they had been published in other places (journal) first.

What exactly is the UCAC3 and how soon do you think the hiparcos New data would be out?

I had a friend do the calculations and he came to the similar distance modulus values as you.

He wrote:

From SIMBAD database here:

SIMBAD Astronomical Database

The primary A component (HIP 104969) has proper motions in RA and Dec: 12.74, -47.79

The secondary B component (BD+67 1298) has proper motions in RA and Dec: 13.70 -47.10

You can see from this the proper motions between the two stars are very closely matched in both RA and Dec.

The parallax for the primary (A component, HIP 104969) is quoted as 13.31 mas (0.01331"). This gives a distance of 245 light years from Earth.

The primary is of spectral class F0. The secondary is of spectral class G5 V. A G-type dwarf like the Sun typically has an absolute magnitude of +4.8.

If we apply the distance modulus of 245 light-years to the secondary star in the pair from the formula:

The apparent magnitude 'm' of a star, whose absolute magnitude is 'M', when seen from a distance of 'd' light-years is given by:-

m = M - [5 - 5 * log10(d / 3.2616)]

Plugging the figure of +4.8 for M, 245 light years for d, we deduce an apparent magnitude, m, of 9.2 for the secondary B component in the pair. Which is virtually identical to its observed apparent magnitude of 9.3.

Therefore, the two stars are virtually 100% matched in proper motions and also virtually 100% matched in distance from us. The uncertainty in the parallax of 13.31 mas in SIMBAD for the primary is given as only 0.67 mas (+/-5%).

The odds of all of this plus for the pair of stars to appear next to one another in the sky and for them to be not a physically connected pair is extremely low.

So it sounds quite promising!!

The Geocities web site where I posted this before has gone out of service.

As luck would have it, I managed to mirror my write ups on all the new double stars I discovered on my Freewebs pages here:

In search of new binaries of the northern sky - by A. Ahad

In search of new binaries of the northern sky - by A. Ahad

I'm working on a paper which I hope to submit to the Webb society journal if I can write it out to a proficient standard.