[AZ-Observing] Re: [Fwd: Re: Re: Rapid motion binary stars]
- From: "Steve Coe" <stevecoe@xxxxxxxxx>
- To: <az-observing@xxxxxxxxxxxxx>
- Date: Thu, 23 Mar 2006 19:37:52 -0700
Brian;
Thanks, I will do that, with that source I should be able to find all =
the
stars that move around each other quickly and could be followed in 3 to =
10
years to see some motion in their orbit. That is what I meant by rapid
motion binaries. I will certainly look over the source your provided. =20
As always, thanks for your time and effort;
Steve Coe
-----Original Message-----
From: az-observing-bounce@xxxxxxxxxxxxx
[mailto:az-observing-bounce@xxxxxxxxxxxxx] On Behalf Of Brian Skiff
Sent: Thursday, March 23, 2006 7:21 PM
To: az-observing@xxxxxxxxxxxxx
Subject: [AZ-Observing] Re: [Fwd: Re: Re: Rapid motion binary stars]
>> REU 1 12:33.5 +0901, 12.6/12.6, 15.9 year period, max 1.2", min =
0.2"
The first thing I do when I ponder an object like this is to
find out where it actually is:
12 33 17.41 +09 01 15.7 (J2000)
That position is for the year 2000, and it is moving 1".7 per year
to the west-northwest.
The magnitudes: it happens to be a Landolt standard, a star that
people use to calibrate photometry. Landolt gives mean V mag of 12.(5
(rounding off), so if the components are exactly equal, they are
mag 13.2 and 13.2, actually visually a couple tenths fainter,
because the pair are so red (B-V =3D 1.85 --- as red as Betelguese).
The faint magnitudes and very close separation (mostly under 0".5)
indicates the pair will be visible only in maybe 24-inch and larger
scopes with great optics and perfect seeing. I'd stick to naked-eye
stars for such objects.
>> LDS 838 01:38.8 -1758, 12.45/12.95, 26.5 year period, max 2.3", min =
0.3"
Another very well-known nearby binary, in this case moving twice
as fast as the first pair, about 3".5 per year proper motion. The =
position
as of 6 years ago was:
1 39 01.52 -17 57 01.7 (J2000)
Similar comments about the visibility as above apply to this pair.
A better, more general approach might be to grab the entire
orbit file from USNO, linked from here:
http://ad.usno.navy.mil/wds/orb6.html
I would delete everything that has components fainter than mag 7 or so.
Then delete everything that has orbit grade of 4 or 5 (all the lousy
orbits). Then I'd delete everything that has a semimajor axis=20
less than an arcsecond. Just as a guess, that'll leave at most 50=20
pairs (whole-sky) that are bright enough to see when close and have
some fairly significant motion. Might be only a dozen in the north.
\Brian
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