• Choose a post by category or constellation

  • Learn the Night Sky

  • Search strategies

    Use the Search box below to find doubles by popular name, RA, or telescope size. For example, a search on "15h" will find all doubles we've reported on that have an RA of 15 hours. A search for "60mm" will find all doubles where we used that size telescope.

Gamma Arietis – head lights on the mountain roads of autumn

Ram’s Eyes  – Mesarthim – (Gamma [γ] Arietis)
RA: 01h 53.5m   Dec: +19° 18′
Mag: 4.5, 4.6   Separation: 7.5″  PA: 0°
Distance: 204 LY
Spectral Classification: B9, Ap

Staring at Gamma Arietis from the coziness of my little observatory I had the distinct impression of being on a mountain road and seeing a car’s headlines, some distance off, heading towards me. The poor seeing actually enhanced the impression, making these nearly identical twin globes bounce around and stretch out from time to time the way you see car head lights poorly through a mist.  (If you’re not sure how to find this beautiful double, check out the finder chart in this post of a pair of  nearby doubles.)

Of course, this impression was dependent upon when I looked. In this case it was mid-August, I was using an Orion 110 ED refractor, and the pair were still fairly low in the east and since they are aligned on a roughly north-south axis they would look that way when rising. Looking again in the early morning of September 19 gave a much different impression. Now the stars were nearly overhead and the side-by-side globes were stacked one on top of another – and now I had an overwhelming sense of what I was really seeing – a pair of incredibly hot and large thermonuclear campfires that had a special magnetic flare to them. In my mind’s eye I transferred the image I hold of bubbling reddish cauldron of our own sun as seen through a hydrogen alpha filter, to this pair of distant suns and it all worked in a way to cause a deep, emotional implosion. Sometimes you just KNOW what you are seeing and the knowledge seems too much.

"Red Rover" - and SV66ED on a Bogen Tripod with the UA Microstar alt-az mount. (Click image for larger version.)

And now it is yet another morning and the nearly full moon is lighting up the southwest and washing out all but the brightest stars. I find the Ram’s Eyes – aka Mesarthim aka Gamma Arietis using the 66mm scope dubbed “Red Rover”  by it’s former owner – if you could see it you would know why.   Wait a  second – I have a picture – here it is!

It’s nice in Red Rover, but I quickly switched to the first classic telescope I acquired, the diminutive 50mm Tasco 6T. At first I was frustrated thinking it can’t split it. Then I realized I was on the wrong star. It splits charmingly with a 12.5 Tak LE – 48X. This is the sort of split that fascinates me because it’s on the edge of visibility. I wouldn’t share it with a visitor for fear of frustrating them and their thinking I was just bragging – no, it needs more than this. So I put in a Tak 5mm – 120X. Ahhh… that’s a view you could share with anyone! Still charming, but much easier.

50mm Tasco with related gear - click image for a larger view.

But as the perfectly matched pair of stars drift across the field of view it goes out of focus. What’s wrong? The Tak, I decide, is a bit heavy for the little Tasco. So I make a quick trip to my workshop and with my observing eye closed to avoid the white light, I pick out a Philips head screw driver and also grab a 7.4mm Plossl -smaller, lighter – and I suspect just right. I think the slightly heavier Tak has been tugging at the rack-and-pinion focuser which turns out to indeed be loose. I tighten the two screws on the bottom of the focuser and now all is fine. But I still change to the Plossl and the result – Plossl Perfect at 81X! OK – I just wanted to say that – but it’s true. This is the combination – the 50mm, the 7.4 Plossl, and the Rams Eyes. Everything is just right – the split is comfortable, the brightness is appropriate – even the 8.5 magnitude field star just 3.5 minutes to the east seems perfect.

It’s that way with doubles – at least for me – in fact, with just about any astronomical object. Of course, it’s highly subjective – but there seem to be one combination where everything comes together to properly frame the object – and then you want to just sit and stare. On this morning, this was the right combination. So what is it, exactly, I was staring at? For that I need to turn to the scientists like James Kaler, for the truth is you are really dealing with a bare minimum of visual information when you sit at the telescope. And here’s some of what Kaler has to say about Mesarthim on his web site.

Famed from history, Mesarthim is also called “the first star of Aries,” as during the ancient times when the stars were being systematically organized, it was the closest of the Ram’s stars to the vernal equinox. (Precession, the 26,000 year wobble of the Earth’s axis, has since shifted the equinox westward to Pisces.)  . . . Both actually white, the (just slightly) fainter one (Gamma-1, since it is the more westerly) has been called “pale grey,” which is a visual contrast effect. Both fifth magnitude (Gamma-1 4.83, Gamma-2 4.75), they combine to make a mid fourth magnitude (3.9) star. Gamma-1, a class B (B9) dwarf, is the hotter, its temperature 11,000 Kelvin. . . . Though Gamma-1 is a bit dimmer to the eye, it is actually the more luminous, as the higher temperature causes more of its light to shine in the invisible ultraviolet. . . .  While Gamma- 1 is relatively ordinary, Gamma-2 is an “Ap” star,the “p” standing for (spectrally) “peculiar.” It is now known that such stars are actually highly magnetized, Mesarthim-2’s magnetic field roughly 1000 times the strength of Earth’s. . . .The stars of the pair are separated by at least 500 astronomical units (over a dozen times Pluto’s distance from the Sun), and take at least 5000 years to orbit each other.

I value such information highly and appreciate all the science involved, but I  find it hard to make that mental transition – to go from this lovely visual image of a couple little pinpoints of light, side by side in the darkness of the telescope eyepiece, to the reality of what  Kaler describes. But when this reality sneaks up on me, the way it did  the other morning, part of me wants to just sit there and stare – and  another part of me wants to drop everything, go back into the house, crawl into bed, and pull the covers up over my head.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: