January 2021

The Women's Group is back

2021 WSIG advert.PNG

Miss getting together to talk and do astronomy over a nosh?  Me, too! Let’s relaunch the Women’s Special Interest Group (WSIG) for 2021. 

Now, it’ll need to look a little different than in past years when we could meet at member homes. But with a little tweaking, we can still observe, still share, and still socialize. Are you in? Contact me at [email protected] and I’ll get you put on the WSIG email list—Rene Gedaly

Challenge Object - January 2021

Original article appears in GuideStar January, 2021.

by: Stephen Jones

NGC-1365 Barred Spiral Galaxy in Fornax

RA 03h33m35.9s Dec -36deg 08’16”

Size 11.3’x6.6’ Vmag 9.3

NGC 1365 is a barred spiral galaxy in the Fornax galaxy cluster, 56 million light-years from Earth.  It was first noted by Australian astronomer James Dunlop (the Southern Hemisphere’s version of Charles Messier) in his 1827 catalog.  It is one of the brightest and largest members of the Fornax cluster.  In my recent investigation of the Fornax cluster for the AL Galaxy Groups program, I observed 1365 last, and found that I had inadvertently left the best for last.  My log is as follows:

11/16/20 12:30 am – 16” f/4.5 203x

Wonderful view; bright round nucleus, with a fainter central bar going roughly NW-SE, a spiral arm coming off the SE end curling back to the north, with a foreground star right in between the arm and nucleus.  The arm coming off the NW end is fainter but also easily seen; both arms are brighter than the bar.  Lovely galaxy.

I was so impressed by my view of 1365 on that night that I even bothered to make a sketch of it, which is something I don’t usually enjoy doing.  The primary reason I made the sketch was to verify when I got home that I was really seeing the details I was seeing.  It was quite thrilling to find, upon looking up photos of the galaxy, that my visual impression was spot-on. 

Messier Objects - January 2021

Original article appears in GuideStar January, 2021.

by: Jim King

M39.jpgThis is the beginning of a new year (the end of a mostly sucky year), with new challenges, new opportunities, and a new emphasis on getting together in the field and having a gay ole time just looking up with our friends.  As far as COVID is concerned, astronomy is recognized as one of the safest pursuits anywhere, which is one reason equipment inventories are so tight…we have lots of new participants.  We need to get to know them.  This is truly an opportunity to make chicken and dumplings out of chicken leftovers (or words to that effect).

We have the opportunity to consistently be out in the fresh air where we can easily maintain safe social distancing.  (I really hate that term…it sounds like something that applies to teenagers at a church social.)  But we can circle up under the stars, have some good conversation and not have to worry about no stinkin’ viruses, with just a little common sense…like keeping eyepieces clean when sharing.

Astronomy challenges the mind in so many ways.  Whether it is the study of physics, cosmology, observing, or chasing that perfect photographic image. There is never a dull moment.  The Universe routinely supplies plenty of surprises.  Frustration, joy, excitement, good friends…it is all there for the taking.

Presented here are a series of monthly columns primarily revolving around observing the Messier Catalogue.   Messier provides easily observed celestial wonders along with objects that will challenge. 

It presents a good opportunity to learn about observing with friends while simultaneously usually having access to those who may be more knowledgeable.  The intent is to provide the reader a sampling of the Messier objects each month that are most visible in the time frame the column is published.  Hence, these deep sky objects should be easily identifiable in and around the month of January.  Some months may have a special treat in addition to the Messier Objects.  Check the trailer. 

Shallow Sky Object of the Month: Beta (β) Aur—An Eclipsing Binary

Original article appears in GuideStar January, 2021.

 Beta Auriga, an eclipsing binary

by Bill Pellerin, GuideStar editor

Originally published in the January 2016 Guidestar

Object:  β Aur
Class:  Eclipsing Binary Star
Constellation:  Auriga
Magnitude:  1.89 to 1.98
Period: 3.96 days
R.A.:    5 h 59 m 32 s (2000 coordinates)
Dec:    44 deg 56 min 51 sec
Size/Spectral:  A2, 9100 degrees K
Distance:   82.1 ly
Optics needed: Unaided eye or small telescope

The schemes for naming stars can be confusing. The Bayer designation consists of the letters of the Greek alphabet (normally in order of brightness) and the genitive (possessive) name of the constellation. The designation β Aur is typical of a Bayer designation.

Variable stars typically have a letter R, S, T, U and so on, and then the genitive name of the constellation, such as R Aur. R Aur turns out to be an unrelated Mira variable that changes from about 7th magnitude to about 14th magnitude.

That said,  β Aur is an eclipsing variable that only drops about .1 magnitude (at the limit of being able to detect visually) every 3.96 days. Given the color of the two stars that comprise this double you’d be correct to assume that these are large stars, and given the period of the orbit you know that they’re very close to each other.

What else can you know from these simple observations? Well, it’s clear that we earthlings are not on a direct line to the orbital plane of these two stars. If we were, the dip in magnitude during an eclipse would be larger than we observe it to be. So, we’re only seeing a partial eclipse of the two stars.

The most famous eclipsing variable star is Algol, the demon star, described in the November, 2006 GuideStar. Algol is so well known that Sky & Telescope magazine publishes a list of the predicted minima of Algol every month.

If you investigate variable stars you’ll find they fall into many categories but the first fork in the road is whether the star is an eclipsing binary or an intrinsically variable (pulsating, usually) star. Eclipsing binary stars represent the first fork in the classification of variables and the easiest to understand. Intrinsically variable stars fall into many categories, identified (usually) by the ‘prototype’ star (one that well represents that category).

By mid January, this star crosses the meridian (i.e. transits) at 22:00 (10:00 p.m.), so it’s very conveniently placed for viewing. Look due north.

That’s not the whole story. There’s a 14th magnitude companion to the pair that lies about 13 arc seconds away. It’d take a larger telescope and dark skies to see this one, though it may be hidden by the brightness of the two primary stars.

Letter from the President - January 2021

Original article appears in GuideStar January, 2021.

Resolving to do more astronomy in 2021

They say hindsight is 20/20, and like most of you, I’m glad to put the year 2020 in the rearview mirror.  I know I’m stating the obvious when I say most of us won’t miss the year that just passed for because of many of the events that happened here on earth, but astronomically speaking, 2020 was actually a pretty spectacular year. In July, Comet NEOWISE became one of the best comets to observe in years, and many of you became members during that time.  In October, Mars came closer than it’s been since the historic opposition in 2003.  And just a few weeks ago, Jupiter and Saturn dazzled us all with a conjunction that brought the planets closer than they’ve been in over four centuries.

But they also say hope springs eternal, and many of us are looking forward to a 2021 that’s better in many ways that the year just passed.  For many of us, that starts with a New Year’s resolution.  I haven’t been a fan of New Year’s resolutions for many reasons – the main one being there are lots of things I need to work on – but this year, I’ve actually made one for myself.  No, it’s not the almost universal “I need to lose 10 pounds”-type resolution, but an astronomy resolution, instead.

So, here it is...

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