Kappa Boötis (Struve 1821)

| 2 Comments

Observation Notes:

This was a subtle and uneven pair. The PA appeared to be 225° with a separation that was obout 1/36 of the 12 arc minute FOV--which works out to about 20 arc seconds. Actual values are 236° and 13.4 arc seconds.

The primary appeared pale yellow with a dull blue secondary. I became a bit frustrated when I was preparing the report for this observation because the primary of this pair is A7V with a F1V secondary. So if anything, I should have seen a light blue primary with a pale yellow primary or a version of that where one of the components was white. Instead I actually had the colors swapped. I decided to do some hunting to see what other observers saw. I found that quite a few that actually mentioned color noted the same swap that I did. Here are the links to those sites:

Search for "Kappa" at those links until you encounter Kappa BOO. These observers (as long as they are listing the primary first) are seeing a bluish secondary every time, and a white or yellow primary. This appears to be a pretty deceptively colored double. But not everyone was deceived:

Double and Multiple Stars and How to Observe Them by James Mullaney features a sketch by Sissy Haas that sports a white primary with a pale yellow secondary. See also, Richard Bell's Double Star Log, where he also sees a white primary with a secondary that has a hint of yellow.

One suggestion I came across in James Mullaney's book is to stop down the aperture of the scope to 3 or 4 inches to see if that helps increase the strength of the star colors. I'll be paying a visit to the fabric store to grab one of those embroidery circles to set up an aperture mask and give this a shot.

SubjectKappa Bootis (STF STF 1821)
ClassificationDouble Star
Position (J2000)[RA: 14:13:27.8 / Dec: +51:47:16]*
Position Angle*236° (1973)
Separation*13.4" (1973)
Magnitudes*4.54/6.69
Spectral Types*A7V / F1V
Date/TimeSEP 25, 2006 - 8:10 PM MST (SEP 26, 2006 - 03:10 UT)
Observing Loc.Flagstaff, AZ - Home
InstrumentOrion SVP 6LT Reflector (150 mm dia./1200 mm F/L)
Eyepieces/Mag.10 mm + 2X Barlow (240X)
ConditionsPartly cloudy, calm
Seeing5/10
TransparencyNELM Mag 5.8
ReferencesThe Washington Visual Double Star Catalog, 1996.0 (Worley+, 1996) and Catalogue of Stellar Spectral Classifications (Skiff, 2005) via VizieR

*Based on published data.

2 Comments

I observed Kappa Bootis with an 80mm refractor at 125X. I saw a pale blue primary. The first word that came to my mind to describe the secondary was "rust." How many rusty stars have you seen?

That's an interesting question--I looked through my notes and haven't found a component that I described as rust colored so far. Although I have noted a few with a dull orange/reddish-orange that might fit the bill:

12 Lyncis (tertiary star)
83 Leonis (secondary)
AG 342 (secondary)
STF 1369 (tertiary)
STF 1521 (secondary)
Xi Bootis (secondary)

I'd have to keep that in mind the next time I have a look at those to see if 'rust' seems appropriate.

Thanks for the comment!

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About this Entry

This page contains a single entry by Jeremy Perez published on September 25, 2006 8:10 PM.

Zeta + 80 Ursae Majoris (Struve 1744/Mizar and Alcor) was the previous entry in this blog.

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