The Galactic Times Newsletter #3 - June 16 - 30, 2021

News, Skygazing Calendar, Podcast, Astronomy in Everyday Life

Cover photo - Sunrise over the Atlantic, June 10th

(credit Rich Stillman, Nahant Beach, Massachusetts)

Welcome to the third issue of The Galactic Times Newsletter! Shortly after this issue goes out, an index to all issues will premiere on the newsletter website, at www.thegalactictimes.com —yes, that is different from the newsletter mailing homepage on Substack, but an index or subsidiary pages are not permitted there.

If you are enjoying this newsletter, please support it by 1) using the link at the end to spread copies to your colleagues and friends and urge them to subscribe (why should you do all the emailing, right?) and 2) buy us a lemonade —it’s hot in Alabama!— at our Patreon site. Thanks!

Dr. Larry Krumenaker.

In This Issue:

  • This Just In — (formerly, Astronomy News)

  • Sky Planning Calendar

  • The Galactic Times Podcast

  • The Classroom Astronomer Newsletter Highlights

  • Astronomy in Everyday Life

This Just In—Astronomy News

* Do We Know Now What Happened to Orion’s Shoulder?

At an AAS plenary talk, Dr. Emily Levesque summarized what astronomer’s now believe we know about what happened to Betelguese, Orion’s red giant shoulder star. Normally bright orangey-red, the star suffered a dimming, a “fainting” spell, in the pandemic winters of 2019-2021 that some took as a possible precurser to a cataclysmic supernova outburst. It has now recovered—rats, no explosion. Three options had been proposed: 1) A cold spot that dimmed the star’s light. 2) Pulsations—red giants do pulse and they do fade in often irregular or semi-regular fashions. 3) Some kind of obscuration due to mass loss or dust production.

Turns out…how about all three?

There did seem to be a slight cooling and darkening of its southern hemisphere but its spectrum overall didn’t change much indicating that its overall temperature didn’t cool, just the hemisphere. The cold spot wasn’t enough.

Betelguese has a known pulsation period of about 430 days, and the star’s brightness usually changes by 0.3 to 1.0-ish magnitudes, no particular pattern to that last quantity. This ‘fainting’ of nearly two whole magnitudes actually fit the 430-day pattern, in timing of the dimming AND of the recovery from it. So it appears that it should be something Betelguese just does, and we just hadn’t seen it before. What would it be? It possibly might be related to some relatively newly named star pairs called Thorne-Zytkow objects, which are red-giants paired with binary companions with which they are in the process of merging, both objects Roche lobes both filled and overflowing over each other. That would explain the variable pulsation in brightness and even some of the irregularity in how much the brightness changes, but….

…there is evidence all around the star of dust from much earlier mass loss episodes. It appears to Levesque that this recent dimming came from dust from an earlier mass loss event, some large-grain gray dust blocking light from the star, that could have been prompted to get in the way by normal pulsations and star convection.

Other stars do these things, but this dimming was the most extreme ever seen.

* Speaking of dust….where exactly does INTERSTELLAR dust come from?

It is standard theory that stars (and planets) are formed from interstellar dust and gas, which we see in dark and emission nebula and, if we are lucky, in protoplanetary nebulae. The stuff that makes up us came from stars that came before us, and…we are told…which supernovaed and spread its new-formed more-complex molecules into space. But that may not be totally correct. Another report at the AAS indicate that a considerable amount may come from another surprising source.

Quite a few elements, and complex molecules such as HCH and HCO, appear to spread from Planetary Nebulae, those short-lived, eerily beautiful ‘smoke rings’ that stars, solar-sized and larger, shed in their later lives. These nebulae are much colder than often expected, survive the shedding of the star’s outer layers, and these complex molecules trace (in radio telescope observations) the colder gases the rings possess and slowly spread out into the diffuse interstellar medium.

* A new jewel in Cassiopeia’s crown.

Back in March, prior to our newsletter starting up, a nova was spotted in the constellation of Cassiopeia, the Queen. In May, it suddenly rose to naked eye level, fifth magnitude, but has now dropped back to binocular brightness. But as we went to press, it was suspected of brightening a bit again. Hovering between 6th and 7th magnitude, it could again break the naked eye barrier (or not—the brightening may have been a blip and the star is fading again). But it is the brightest such star in a few years so it bears monitoring. For observers north of, roughly, latitude 33 degrees north, it is circumpolar, but higher with each passing hour after midnight.

The chart below, created from Stellarium, shows its position. The star Caph is Beta Cass, the last star on the right of the “W” of the Cassiopeai asterism, and is placed as it would be near the horizon at midnight.

* Where came the Oort Cloud? Partially, from other stars.

A team of Leiden Observatory (The Netherlands) astronomers has managed to calculate the first 100 million years of the history of the Oort cloud in its entirety. Until now, only parts of the history had been studied, separately. The cloud, with roughly 100 billion comet-like objects, forms an enormous shell at the edge of our solar system. The astronomers will soon publish their comprehensive simulation and its consequences in the journal Astronomy & Astrophysics

The Oort cloud was discovered in 1950 by the Dutch astronomer Jan Hendrik Oort to explain why there continue to be new comets with elongated orbits in our solar system. The cloud, which starts at more than 3000 times the distance between the Earth and the Sun, should not be confused with the Kuiper belt. That is the rim of rock, grains and ice in which the dwarf planet Pluto is located and which orbits relatively close to the Sun at about 30 to 50 times the Earth-Sun distance. 

Loose events tied together 

How exactly the Oort Cloud must have formed has remained a mystery. This is because a series of events had to take place which a computer could hardly reproduce in its entirety. Some processes lasted only a few years and took place at relatively short distances, comparable to the distance between the Earth and the Sun. Other processes lasted billions of years and took place over light years, comparable to the distances between stars. Leiden astronomer and simulation expert Simon Portegies Zwart explains: "If you want to calculate the whole sequence in a computer, you will irrevocably run aground. That's why, until now, only separate events were simulated." 

The Leiden researchers started from separate events, as in previous studies, but new is that they were able to connect the events with each other. For example, they used the end result of the first calculation as the starting point for the next calculation. In this way, they were able to map out the entire genesis of the Oort cloud. 

Comets from inside and outside the solar system 

A press release from the Leiden Observatory in the Netherlands claims they have finally figured out the birth chronology of the Oort cloud, a complex computational problem that has perplexed astronomers since the cloud’s discovery 70 years ago. The claim is it is “a remnant of the protoplanetary disk of gas and debris from which the Solar System emerged some 4.6 billion years ago. The comet-like objects in the Oort cloud come from roughly two places in the Universe. The first group of objects comes from close by, inside the Solar system, debris and asteroids thrown out by the giant planets. However, some of the debris is still in the asteroid belt between Mars and Jupiter. The second population of objects comes from other stars. When the Sun was just born, there were about a thousand other stars in the vicinity. The Oort cloud may have captured comets that originally belonged to those other stars. “

In addition, the Oort cloud was formed relatively late, after the Sun had been ejected from the group of stars in which it was born, nor was the cloud caused by the outward migration of the giant planets in the Solar system, as some have conjectured.

Free preprint: https://arxiv.org/abs/2105.12816

Sky Planning Calendar

Moon-Gazing

Moon passages by a star, planet or deep sky object are a good way to find a planet or other object if you’ve never located it before.

June 15      The nearly First Quarter Moon passes north of the star Regulus, at the bottom of the Question Mark-shaped head of Leo the Lion.

June 18      First Quarter Moon.

June 19 The Moon passes by bright star Spica, in Virgo.

June 24 The Moon is Full and lies north of bright red Antares in Scorpius.

June 25 The star Sigma Sagittarii is occulted (covered up) by the Moon. This is best seen in the western USA, and though the star is bright, and one of the stars that make up the handle of the Sagittarius ‘Teapot’ asterism, you’ll really need a pair of binoculars or a telescope to catch the Moon’s bright edge move up to and cover up the star. Still, this is a better opportunity than most to witness a stellar occultation.

June 27 Saturn can be found tonight four degrees north of the Moon.

June 28 Not to be outdone, tonight Jupiter does the same as Saturn did last night, and is closest in between the 28th and 29th, for those in the Eastern Hemisphere.

For the Future

Woman and Man, er, Venus and Mars have a close encounter in the July evening twilight. Mars later hangs out with the heart of the big cat, Regulus, in Leo. Hmmmm.

In a month, Saturn will rise with the Sun setting, prime observing season for its rings, disk and moons.

Border Crossing

Yes, the Solstice is coming and the Sun is in….Gemini?? Yes, while the traditional zodiac has the Sun entering the sign of Cancer on the 21st, the Sun actually enters the Gemini twins constellation on the 20th and remains there for the next 31 days. I guess if your birthday is in the next 31 days, you don’t have this excuse to be crabby…..

Observing---Plan-et….                                    

Solstice….11:32pm EDT, June 20th. Astronomical summer for northern hemisphere, winter for the southern hemisphere. Weather, as usual, has jumped the gun for most of us. It is also the longest day for those around 40 degrees north latitude, a minute longer than 15 hours! No, you do NOT have to work during all those sunny hours…unless you want to…..

Mercury is a very nice morning star but nice only if you are in the Southern Hemisphere.

Venus is starting to hit its stride. When is the first day you catch it easily in the twilight without binocular help first?

Mars, in the southwest, dimming, tiptoes through the Beehive star cluster (a.k.a. Praesepe, or M44). Use this last decent opportunity to see the cluster before next winter. But you only get around an hour or so after the Sun sets to find Mars and the Bees so use binoculars!

On the 26th, Mars and Saturn are exactly 180 degrees apart on the sky, in opposition to each other. When Mars goes down, Saturn appears rising on the opposite side of the sky.

Jupiter, to the left of Saturn, rising about an hour later, well before midnight.


Solstice is coming! Check if it is on-time with the Hermograph Wearable Sundial T-Shirt! Works as a clock or a compass.


The Galactic Times Podcast

Exoplanetary Music

(The podcast on Exoplanetary Music has been postponed slightly, simply due to complexity of the editing, and because we just spent three exhausting days attending the American Astronomical Society virtual meeting -pant, pant-). Johannes Kepler believed the planets moved with heavenly tones. Some have even created music with them, in modern recordings. But now some have done the same with exoplanetary systems. Tune in to The Galactic Times Podcast, approximately June 25th on your favorite podcast service to hear it, including (we hope!) the first ever sounds of 55 Cancri’s system!

Astronomy in Everyday Life

As we went to press, a head-shaking political moment……one of Texas’ US Representatives, Louis Gohmert, at a hearing about climate change, noting that some changes in climate are apparently due to changes in Earth’s orbit, and effects of the Moon in its orbit and that a past director of NASA had found that both orbits had been found to be changing, Gohmert actually asked a member of the National Forest Service or the Bureau of Land Management, if there is anything they can do to further change their orbits to cause any change in climate to occur in a more positive manner.

Really.

****

Proper fashion for young astronomers:

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The Classroom Astronomer Newsletter Highlights

This premium newsletter will be for paid subscribers only, but if you click this link, for an introductory time, you can read this for free!

  • Cover Story
    Photographing the Solar Eclipse, and the Sun; What can you learn?; Different ways including with a Pringles Can; Upcoming solar eclipses

  • Connections With The Day Sky
    Virtual Radio Astronomy/Observatory Tours

  • Astronomical Teachniques
    Earth Rotation
    Words Matter

  • RAP Sheet – Research Abstracts for Practitioners
    “QuaRCS”


Coming Soon!

Learning Astronomy Under The Northern Stars – A 365-Night Per Year Textbook

Use the stars that are ALWAYS visible to understand basic astronomy, stellar evolution, galactic structure, with the naked eye and common binoculars.  EBook (late spring) and print book coming (summer).  Detail description and advance orders link coming soon.


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Thanks for reading. Until the next newsletter, stay safe.

Dr. Larry Krumenaker

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