star – A Darker View

A Changing Sky

Gazing up at the sky while reading the old texts one would not be amiss in believing that the stars never change. Indeed there are many who insist vehemently that the stars are eternal and unchanging. But the stars do indeed change, often quite visibly, sometimes within the span of a human lifetime.

VLT/SPHERE image of the star L2 Puppis and its surroundings — A VLT/SPHERE image of L² Puppis showing the enveloping cloud of gas and dust representing an early stage planetary nebula. Image credit ESO/P. Kervella used under Creative Commons 4.0

One such star is L₂ Puppis.

A bright star, one of the few naked eye variable stars that could be seen to fade and reappear without the aid of a telescope much like the far more famous stars Mira and Algol. On star charts the star is found prominently drawn at magnitude 4, buf if you attempt to locate it today you will not find it without the use of a telescope.

I first encountered this star quite recently while starhopping through southern Puppis with an 8″ telescope from the driveway. The chart showed two bright stars close together, L₁ Pup and L₂ Pup, while the view in the finder ‘scope showed only one bright star.

Of Green Stars…

Wandering the sky using a telescope and a field guide published in 1844, the better part of two centuries ago, is… uhhm… interesting. In mid-April the classic winter constellations are dissapearing into the sunset, with constellations like Monocerus and Puppis well placed for observing from my driveway just after dark. On my observing table is a reprint of that 1844 field guide, The Bedford Cycle.

Working through the entries I come to the entry for a double star Argo Navis 72 P. VIII, a designation from a very old catalog. It takes a few moments research to convert 72 P. VIII to the slightly more modern catalog number HD 71176. Modern? The Henry Draper Catalog was first published by Harvard Observatory in 1918, still over a century ago.

With the HD number I can look up the position on a modern chart and spend a few moments star-hopping the Astrola to the correct star. This double star is now located in the constellation Puppis after the ancient and absurdly large constellation Argo Navis was broken up into Puppis, Vela, and Carina.

Star Types

I have been observing a lot of stars during my driveway sessions at the telescope lately. Some of these are new to me, will have to look them up and hunt them down…

Betelgeuse Fading

Something is definitely not right with Orion. For anyone familiar with the sky the constellation just looks wrong with Betelgeuse at half its normal brilliance.

We have long known Betelgeuse is a dying star, in the last stages of its life. Old stars tend to be unstable, changing in brightness. Betelgeuse has always varied a bit, but this is the largest change on record.

The magnitude of Betelgeuse over the past 35 years, data from the AAVSO

It is odd to see such an iconic star change so dramatically, a reminder that not even the stars are permanent.

Orion with a faint Betelgeuse changing the appearance of this familiar constellation, photo taken December 29, 2019

The photo tends to flatten the magnitude of stars, the difference is not as obvious. You need to step outside and look for yourself. Orion currently rises late in the evening.

A Dark Night

WHAC members setup at Kaʻohe, 12 May, 2018

Astrola and Milky Way

The 8" Cave Astrola under the Milky Way — The 8″ Cave Astrola under the Milky Way at Kaʻohe

Under the Stars

A Waikoloa Star Party

It started simply enough… Donna asked for suggestions, she was looking for activities the Waikoloa Village Association could share with the community. Of course I suggested a star party. Much of our small club lives in the village, this would be an easy and fun event to put together. Al we need is a date and a place.

A date? Sept 23rd would offer a slim crescent Moon, Saturn, and the Milky Way overhead. The 23rd has the added benefit of being a Saturday.

A place? The Waikoloa Stables have ceased being a place with horses. There remains a nice lawn, bathrooms, and a large parking lot. The stables currently hosts a thrift shop and regular community events like the yearly Wiliwili festival.

A plan? Easy… Light refreshments, parking coordination, keiki fire dancers, the local CERT team for safety backup, a sound system, a speaker for the evening, and at least five telescopes for viewing. OK, maybe not so simple.

We can do this.

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Oregon Star Party 2017

Due to lucky happenstance the location for Oregon Star Party, the same location used for decades, was within the path of totality for the 2017 total solar eclipse. This provided an opportunity to both attend the star party again, and to view the eclipse.

I do enjoy the large star parties, something we do not have on the island. I had attended OSP a few years ago, the eclipse made the opportunity to attend once again very tempting.

Registration for the star party was an issue. Due to the eclipse attendance was going to be very good, so good that registration was closed within two hours of opening! I got the announcement email, then waited until I got out of a meeting to register, only to find out I was too late! I put my name on the waiting list and hoped.

With a month to go I received word that my waiting list position was opened for registration. By this time my family already had plans to camp in the Ochoco Mts. for the eclipse, no reason not to do both!

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Astronomers Prove What Separates True Stars from Wannabes

W. M. Keck Observatory press release…

Astronomers have shown what separates real stars from the wannabes. Not in Hollywood, but out in the universe.

“When we look up and see the stars shining at night, we are seeing only part of the story,” said Trent Dupuy of the University of Texas at Austin and a graduate of the Institute for Astronomy at the University of Hawaii at Manoa. “Not everything that could be a star ‘makes it,’ and figuring out why this process sometimes fails is just as important as understanding when it succeeds.”

Dupuy is the lead author of the study and is presenting his research today in a news conference at the semi-annual meeting of the American Astronomical Society in Austin.

He and co-author Michael Liu of the University of Hawaii have found that an object must weigh at least 70 times the mass of Jupiter in order to start hydrogen fusion and achieve star-status. If it weighs less, the star does not ignite and becomes a brown dwarf instead.

How did they reach that conclusion? The two studied 31 faint brown dwarf binaries (pairs of these objects that orbit each other) using W. M. Keck Observatory’s laser guide star adaptive optics system (LGS AO) to collect ultra-sharp images of them, and track their orbital motions using high-precision observations.

“We have been working on this since Keck Observatory’s LGS AO first revolutionized ground-based astronomy a decade ago,” said Dupuy. “Keck is the only observatory that has been doing this consistently for over 10 years. That long-running, high-quality data from the laser system is at the core of this project.”

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