Distance between 16 Cygni and HD 108874

I've tried posting this to a few other Usenet groups, but no luck.
Does anyone here know the distance between the 16 Cygni and HD 108874
systems, or how I could get that information? Thanks in advance.

In article
,
Damien Valentine wrote:

Does anyone here know the distance between the 16 Cygni and HD 108874
systems, or how I could get that information? Thanks in advance.

According to Simbad, 16 Cygni A (AKA HD 186408) is at RA 19h41m49s, Dec
+50°31'30"; with a parallax of 46.25 +/- 0.50 mas it's 21.6 parsecs
(70.5 light-years) from here. The corresponding figures for the 16 Cygni
B (HD 186427) system are all quite similar -- not surprising as it's
very close by.

http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=16+Cyg
http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=16+Cyg+B

The HD 108874 system is in Coma Berenices at RA 12h30m27s, Dec
+22°52'47", with parallax 14.59 +/- 1.24 mas for a distance of 69
parsecs (220 LY) from the Solar System.

http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=HD+108874

Can you work out the actual distance between the two systems from these
data, or do you need some help with that? Offhand, without calculation,
I'd guess it's between 200 and 250 LY, but from the application of a
little geometry we should be able to get an estimate within about 5% of
the true distance. (The largish standard error in the parallax for HD
108874 indicates that we can't expect to do much better than that.)

--
Odysseus

On Dec 13, 1:39 am, Odysseus wrote:
In article
,
Damien Valentine wrote:

Does anyone here know the distance between the 16 Cygni and HD 108874
systems, or how I could get that information? Thanks in advance.

According to Simbad, 16 Cygni A (AKA HD 186408) is at RA 19h41m49s, Dec
+50°31'30"; with a parallax of 46.25 +/- 0.50 mas it's 21.6 parsecs
(70.5 light-years) from here. The corresponding figures for the 16 Cygni
B (HD 186427) system are all quite similar -- not surprising as it's
very close by.

http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=16+Cyg
http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=16+Cyg+B

The HD 108874 system is in Coma Berenices at RA 12h30m27s, Dec
+22°52'47", with parallax 14.59 +/- 1.24 mas for a distance of 69
parsecs (220 LY) from the Solar System.

http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=HD+108874

Can you work out the actual distance between the two systems from these
data, or do you need some help with that? Offhand, without calculation,
I'd guess it's between 200 and 250 LY, but from the application of a
little geometry we should be able to get an estimate within about 5% of
the true distance. (The largish standard error in the parallax for HD
108874 indicates that we can't expect to do much better than that.)

--
Odysseus

Thanks! That should be quite enough for me. Shame about the parallax
error, but whaddaya gonna do...

In article
,
Damien Valentine wrote:

snip

Thanks! That should be quite enough for me. Shame about the parallax
error, but whaddaya gonna do...

If we were to put an astrometric satellite into solar orbit at about
Saturn's distance, say, we'd get a much longer baseline and accordingly
better parallaxes for stars in the hectoparsec range like HD 108874. Not
likely to happen soon, though, and the data-collection would take
decades ...

OTOH systems with extrasolar planets will tend to be scrutinized more
closely than average, so there may be improved ground-based parallaxes
forthcomimg for some such objects over the next few years.

--
Odysseus