Last Friday, as he looked to the amazing blog of my friend Oscar "The Edge of the Cosmos" . I saw a new entry referring to the open cluster Cr399 , familiarly called "The Roost" and that caught my attention.
More than quality, to which Oscar he usually does, this post I found rather interesting for two reasons:
- The first is that despite many years of love, is about an asterism that although he knew from references in books and pictures of some classmates, had never before seen "live."
- The second is that inside my favorite things, are the clusters. And especially the double stars that can be found in them.
There is a branch of astrophysics that studies the dynamics and evolution of star clusters to know how often and in what situations, two stars belonging to the same group, they can end up forming a physical system ... come into play several factors such as the cluster's stellar density, stellar masses, the gravitational influence of a star on one another, the disintegration of the cluster levels, etc. Hence the importance of the study of double star clusters ...
should be noted that just as with the double optical double not all that we can locate in a star cluster necessarily belong to it. Therefore it is essential to calculate a part of many data to individual distances for each of the pairs ...
But that's another story ...
The fact is that the same Friday, directed by Oscar and my 10x50 binoculars I found it very easy to enjoy this interesting and beautiful open cluster. As pointed
Oscar. Almost halfway line between Vega and Altair (Altair something closer) and located just south of the line extended Deneb, Albireo we find it worth Cr399 ... enjoy it. Like
twice about Perseus, the Pleiades, or the manger, is one of those objects for a relaxed ending any observing session.
How could it be otherwise ... My "alter ego "doubles player, has not been able to resist, so once again I'll give the can a while talking about the double that you can find posted on this particular celestial perch ..." "That Habel Hail". "
believe it or not, there are few star systems linked to Cr339. Even we can find a five-and even three pairs "neglected".
A table with the main data of each pair.
And to whet your appetite a picture with the location of each within the cluster.
On Saturday, as it was cloudy night, I could not spend even a little bit. So, until next week. So in the absence of updated pictures (for now ...) I advance that's what you can find if you decide to immortalize these pairs ...
And while I show you what is the methodology that I follow (and not have to be the best ...) to prepare an observing session with peers "neglected" included.
Here are some comments and the plates identifying the components for each of the systems.
HDS 2752 (WDS 19243 +2032). This pair with a main component of spectral type F6V and a separation of 0.2 " is beyond the scope of our teams, so I simply listed for you to know of its existence. HJ
2871 (WDS 19255 +1948). Here we found a triple system whose component "A" (4Vul) presents a spectrum G9III. The pair "AB" has not been measured since 1984, so we can look "neglected". Despite the difference of over five magnitudes between the principal and her companions, this is a trio with comfortable spaces between your components so we should not have more problems to solve.
STF 2521 (WDS 19265 +1953). This system is itself a small open cluster. We met with 5 components of magnitudes between 5.8 and 14.5 and a red main spectral type K5III. Despite large differences in magnitude and HJ Like 2871, the comfortable separation between the components makes sure we photograph a lot of work and measure. Noted that the pair "AE" also called "Aa" has been measured only twice, the last in 1934, so this is another manual ...
neglecta
A STF 159 AB + 2527 AC (WDS 19273 +2040). triple system consists of a main spectrum magnitude 8.5 and B9, a component "B" 10.43 magnitude and located just 0.6 "(at the limit of separation of the team) and a 9.73 magnitude tertiary affordable located about 4.3".
COU 514 (WDS 19276 +2009). Another pair of those inaccessible. With a spectrum B8V and a separation between the components of only 0.5 "is a pair of professional telescopes. Anyway, here I leave for you to know of its existence. STF
WAL 3132 + 113 (WDS 19282 +2013). are two couples who share a primary magnitude range 10.1 to 113 AD WAL G5.El pair is the pair forgotten and we needed ... also unconfirmed!. With a single measurement since 1934, I have the pleasure to announce that in the POSS plates can identify and confirm without any doubt the existence of this pair forgotten for over 75 years.
Ending this planning for a future session of observation ...
STF 2530 (WDS 19284 +2019). With a G0 type host component, it is a comfortable pair, both for the slight difference of magnitude (deltamethrin 1.3) as the separation of 5.6 ".
And .... Soon the pictures with the updated measurements of these curious peers.
I hope that reading this post I animeis to immortalize this beautiful cluster doubles player and all the treasures it holds.
Indeed Oscar ... Thanks for exposing those celestial wonders and motivate us to watch.
