Double and Multiple Stars

“La Superba”, Y Canum Venaticorum.

The happy hunting grounds of the “Hunting Dogs”, Canes Venatici are well placed. This glorious area beneath the handle of Ursa Major. A favourite area and kicking off point for the Coma Virgo galaxy clusters.

It holds many galaxies including the magnificent M51( 27 million light years away) M94 (16 million lys away)and M63. A few years ago these were good targets from the edge of town. Light pollution has worsened . On rare nights  “The Whale”, “Cocoon” and “Hockey Stick” still come out. The most stunning being NGC 4449 which resolves to stars. However for small scopes and bad skies there are some stars worth locating.

Canes V is marked out as a line between Cor Caroli (“Heart of Charles”)at 115 lys away and fainter Chara at 27 lys away. These are useful pointers for galaxies. Cor Caroli is a wonderful binary for small scopes. It’s easy to find by eye and half way between it and Arcturus is the globular bright M3. A most useful pointer.

In addition there is a lovely star in CNv which I use as a tester for observing conditions, the fabulous “La Superba”. Once again, small aperture will serve you well, scooping up maximum colour. See what you think. If you can still get “Hind’s Crimson” star, you’ll see the much finer colour of this “Vampire Star”. Be aware that both these carbon giants are variable , catch them at their brightest !

Back to the superb one.Here’s its location and a few notes from Jim Kaler.

Y Canum Venaticorum – La Superba
Y Canum Venaticorum, called “La Superba” by the 19th-century Italian astronomer Father Angelo Secchi, is one of the deeply red-toned “carbon stars.” Y CVn is a semi-regular (SRb) variable star; its magnitude range is from 4.8 to 6.4, over a period that averages roughly 157 days. Other periods, including one of 2000 days, are suspected. “Y” is one of the reddest stars in the sky, and is classified variously as a C7 supergiant, or as a CN5 supergiant. Its beautiful poppy-red tone is easy to see in 50 mm binoculars.

Properties

Carbon stars are highly evolved cool red giants with atmospheres rich in carbon molecules. Most red giants and supergiants are richer in oxygen than carbon; carbon stars reverse the ratio. The unusually deep red color of these stars is the consequence of the efficiency of these carbon molecules in absorbing the star’s blue light.

Carbon stars were originally classed as warmer “R” and cooler “N,” and are now combined into class “C.” As giants, they are dying, and are in a mass range where the carbon byproducts of helium nuclear fusion are lofted to the surface before escaping into space. Huge absorptions by carbon monoxide, cyanogen or CN, carbon-2, and carbon-3 are present, giving the star its remarkable spectrum. The beauty of the spectrum is what caused Father Secchi to gave the star its name. It was described by Agnes Clerke in 1905 as having “extraordinary vivacity of its prismatic rays, separated into dazzling zones of red, yellow, and green, by broad spaces of profound obscurity.”

With a surface temperature of 2200 K, La Superba is one of the coolest of naked eye stars, though one authority puts it at 2800. At 710 light years away, the star’s luminosity is 4400 times the Sun’s, after a large correction for infrared radiation. This gives it a radius of about 2 AU – notably larger than the orbit of Mars. La Superba is most likely in the process of becoming a luminous giant for the second time, brightening with a dead carbon-oxygen core. Its mass is not well defined, but was probably initially at least three times the Sun’s.

Typical of its breed, Y CVn is losing mass, at a rate of about one ten millionth of a solar mass per year – a million times that of our Sun’s own solar wind – with a flow velocity of about 10 km/sec. Y CVn is surrounded by a huge detached shell of matter with a diameter of around 2.5 light years. The shell subtends an astounding 11′, or 0.2 degrees, as seen from Earth. It implies that the mass loss rate was 50 times higher in the past. La Superba seems poised to eject its outer envelope, becoming a planetary nebula with its dead white dwarf core at the center.

La Superba is also the sky’s brightest “J star.” These are a very rare set of carbon stars which have a huge elevation of the heavy isotope carbon-13. Though carbon-13 (with 7 neutrons in its nucleus rather than 6) is readily made in the nuclear reactions that help generate stellar energy. But no one quite understands what causes it to be so abundant in the J stars.

[Adapted from STARS by Jim Kaler, Professor Emeritus of Astronomy, University of Illinois]

clear skies ! Nick.

Binaries under the Moon.

Cold , clear and a bright moon. It was struggle to get contrast with NGC 2903 just showing and M67 bleached out. The main stars of M44 held. Once again binaries gave some cracking views in particular with tight separations and some faint companions spotted.

Talitha in UMa proved once more very elusive , I spent some time with filters , eventually just managing to squeeze out the small puff of the secondary in the glare. There was lots of colour on show. The best being. Low power visit to ” La Superba ” in CNv. There are some fantastic binaries here.

Back to Cancer and “Tegmine”. What a superb split at x216. It held perfectly stable at a widening 1.1″.
57 Cancri showed a slightly easier 1.5″, delightfully bright and even in a lovely star field.
Up to the rising UMa .
57 giving a lovely delicate companion at x150.
65 showing the lovely triple of differing magnitudes. It’s superb to increase the magnification to split these open.
Then a real favourite and showcase at,
Σ1831,this obvious line of stars splits open to show a most delicate pair at x 150.

A bit of a struggle with the moon behind. Kept get bright flashes off my glasses ! High misty stuff with a deep ground frost completed a very satisfying session,
Old Nick.

Best binaries and triples in Taurus.

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Recently , observing has been through milky skies with weather systems shifting quickly at height. There hasn’t been enough contrast for filling in clusters or observing galaxies.
Time for some binaries. Early evening views of Taurus have meant sitting comfortably at the eyepiece. Taurus is stacked with binaries, one of the few visible by eye is in the Pleiades.

Σ479 shows a wide but delicate L shaped triple. RA 04h00.9m. +23 12′
Σ523 SAO 076552, dim pair at 10.2″.
52 Tauri (φ) SAO 076558, ghostly speck gives light red and blue.
Σ559 shows a wonderful bright exactly even pair, really lovely.SAO 094002, just spectacular.
Σ7 and Σ401 are both caught in the field of view at x50, this is better than the double double. A really beautiful sight.SAO 075970.
Σ430 shows a delicate and difficult amazing looking triple with two faint companions , I often wonder what a sky with three suns would look like.
SAO 11340.
Aldebaran is a binary with a wide +11.3 companion, worth spotting.

Finally across the Moon this morning , a glimpse of someone practicing delivery, Happy Christmas and all the best for 2017 !
Old Nick.img_4364

4″ refractor , December sky.

Set up, quite a milky sky , not looking very nice. However the setting of the waxing moon promised a darker sky later on.Humidity picked up all the light pollution throwing it high into the sky.The dew set in so badly ,it dripped off the scope , then froze.

I gave it a couple of hours, leaving the dew heater and air to perform. Went out and there a small breeze and a surprising rise in temperature. The dew eased off and I packed in at 2. The sky ended up up very misty, by eye , just a few stars out.

Gemini dominates the early eastern sky. Mekbuda is very much overlooked .

Monoceros is a lovely area to explore. 10 Monocerotis is rarely referred to. I spotted a very delicate binary near Beta , I hadn’t noticed before.

Eridanus runs down beside Orion, quite low in the south.

Ursa Major towers on it’s tail , high in the north. Xi is a beautiful , fine and bright binary, again very much overlooked.

Leo, Coma Berenices appeared , but the haze obscured so much. Early morning showed a bright Spica in the north east and a bright Jupiter in the south. Plenty treats to come , under

Clear skies  !

Nick.

img_4253img_4252img_4251img_4250I was very pleased to get results in 4″ of f10 aperture. The scope is over 30 years old with lovely optics , just a delight to use and explore . A bit of sketching keeps frost off the fingers !

December treats.

img_4241img_4240Some spectacular targets out there.

Iota Cancri is one of the colourful winter Albireo contenders.

Hinds Crimson is a deep red carbon star, in Lepus , below Orion.4″ aperture will give you lots of colour.

Zeta Cancri is the wonderfully bright Tegmine. Use Some aperture and magnification to split open the triple.

Ngc 2301 is in Monoceros, a lovely cluster “Hagrid’s Dragon”. It’s wings and head fill out under darker skies .

Don’t forget M67 and M44,

Nick.

15 Monocerotis

Inspired by Nick’s comment, I revisted my window-sill captures of NGC 2264 to see if we could see much of 15 Monocerotis. I had taken some shorter exposures, so selecting  and stacking the best frames of these produced the attached image. Bear in mind that the arrangement was hardly conducive to double-star spotting being through the double glazing with a short focus refractor AND a focal reducer together with a (very) approximate drive!

ngc2264_samworth_301116d

A bit of research on the web indicated that there were up to 16 components to 15 Monocerotis! The brightest 6 were described as:

15 Monocerotis, also known as S Monocerotis, is another multiple system consisting of six stars. However most of them are very faint:

AB: 4.7, 7.8; 213º, 2.9″.
C: 9.9, 14º, 16.4″
D: 9.7, 308º, 40.7″
E: 8.9, 140º, 73.8″
F: 9.0, 222º, 155.5″.

Taking the separations above and their PAs, I have labelled up what I think are the separable components. There is no chance of separating A,B & C with this set-up!ngc2264_samworth_301116e

Review: “Double stars for small telescopes”.

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A classic , just packed with the very best binary , optical and multiple stars. There are details of historical observations and Sissy’s comments. There’s enough room to add your own notes . There are also details of what hasn’t been spotted with various apertures and a range of colours experienced.

There’s a very full introduction to observing double stars. It’s taken me on many adventures. Each constellation is accurately detailed with challenges down and just below one arc second. With light pollution , double stars are very obtainable targets in any scope.

This will kick off your adventures. More can be found on the “Eagle Creek observatory , double star “site and the very comprehensive “Star splitters” site.

Nick.

Stars of Ursa Major.


Looking up and pointing out stars that have stories adds to the fascination of the night sky.
Let’s look at the stars of the “plough”.

Dubbe (α) is a very wide orange and brown pair at low magnification.

Mizar and Alcor are optical doubles, the bright one , Mizar opening out to give a 14.3″ split.

Talitha (ι UMa) shows a white and a close 4.5″ blue, I found this quite a challenge.

Σ1523 (53 UMa, xi )(Alula Australis), a superb widening binary 1.7″ at +4.3 +4.8 with an orbit of 59.8 years. This was the first ever binary discovered on 2nd of May 1780 by Sir William Herschel and the first visual double for which the orbit was found.
To the north is Lalande 21185 a red dwarf +7.5 at 11h30.3m. +35 58’11”. This is the fourth closest star and nearest planetary system at 8.32 lys.
Next door is Groombridge 1830 (Argelander’s Star) the third fastest proper motion star , moving one degree every 511 years. At +6.4 go to 11h52.9m. +37 43′.

Some colours and showcases now,
Σ1193 shows a wide orange and blue at x50.
23 UMa shows yellow and green, there is a third element at 100″ being +10.5.
Σ1415 shows a pair at 16.5″.
Σ1495 between Merck and Dubhe shows an easy wide lovely pair.
h 2554 is a wide 40″ with plenty colour here.
57 UMa a lovely white and blue at x100.
Σ1559 I use as a tester, a lovely delicate companion at 1.8″.
65 UMa is a colourful triple , worth a long look.
Σ1603 gives a lonely pair of headlights at x50.
Σ1695 gives a lot of colour at 3.8″. As does the blue companion of
78 UMa at a close 1.2″.
Σ1770 , a most delicate pair, but I caught it in the 102. More colour at
Σ1795 at 7.9″. I’ll end with the very delicate
Σ1831 an arc of a triple at x50.

All these were caught from the street lit edge of town. The only good thing about permacloud is going through old notes. I found a scribble suggesting that the optimum magnification for observing binaries is 750 divided by the arc seconds. That combined with your maximum magnification being your aperture in inches x50, food for thought. That is under the
Clearest skies !
Old Nick.

Below are some night shots with a compact camera, no mount , just on 30 seconds propped up on a chair. The constellations are very hard to identify and it’s great to see stars down to the horizon.

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Binary stars for December.

Some class targets and colours here. Included are the RA and DEC and the SAO number . These are possible with light pollution. Preferably using a refractor ( proper scope), 4″ of aperture giving maximum colour. I have managed down to 1.1″ using a 150mm achro. This is limited by seeing at x216.

Usually slight defocussing has opened up diffraction rings. The results were surprisingly better in the 127mm , focussing snapping into place. img_4174img_4173

Given a bit of time I’ll fettle a guide to observing binaries and some details of the finest of these currently on view under ,

Clear Skies !

Nick.