Saturday, 28 December 2019

The Current Historically Unprecedented Dimming of Orion’s Shoulder Star Betelgeuse

The Current Historically Unprecedented Dimming of Orion’s Shoulder Star Betelgeuse


Some recent reports via the Astronomers’ Telegram ( entitled “The Fainting of the Nearby Red Supergiant Betelgeuse” and “Updates on the ‘Fainting’ of Betelgeuse” comment on the continuing dimming of the star Betelgeuse, in the constellation Orion.  That would be the (normally) bright star that represents Orion’s left shoulder (left from the observer’s point of view).

“Betelgeuse and Antares are the two nearest red supergiant core-collapse Type-II supernova (SN II) progenitors.  Photometry from this season shows the star has been declining in brightness since October 2019, now reaching a modern all-time low of V = +1.12 mag on 07 December 2019 UT. Betelgeuse undergoes complicated quasi-periodic brightness variations with a dominant period of ~420 +/-15 days. But also Betelgeuse has longer-term (5 - 6 years) and shorter term (100 - 180 days) smaller brightness changes. Currently this is the faintest the star has been during our 25+ years of continuous monitoring and 50 years of photoelectric V-band observations.” ATel #13341 8 Dec 2019; 03:57 UT

A slightly later report had some further information.

“The most recent measurements made on 2019 December 19.3 UT, 20.2 UT and 22.25 UT are V = +1.273, +1.294 and +1.286 mag, respectively. This appears to be the faintest the star has been measured since photoelectric observations have been carried out of the star… At its average maximum brightness light (V ~ 0.3 - 0.4 mag), Betelgeuse is the 6 - 7th brightest star. But by 2019 mid-December the star has slipped to the ~21st brightest star. The red supergiant is now closer in brightness to Bellatrix (V =+1.64 mag) than to Rigel (V =+0.13 mag).” ATel #13365 23 Dec 2019; 20:24 UT

So Betelgeuse has dimmed from about -.4 to about 1.29.  That’s about 1.7 magnitudes reduction (the magnitude scale works backwards, with larger positive numbers indicating less bright objects).  In terms of absolute brightness (luminosity), that means the star is about 4.7 times brighter at its usual maximum than it is now (2.51 raised to the exponent 1.7).  However, it should be noted that the magnitude scale is closer to what the eye sees, so the star seems to be about 60% as bright as it does at its peak (1/1.7).

The series of iPad/iPhone photos that I have taken over the past few years shows this difference visually.  The September 2016 iPad photo shows Betelgeuse being much brighter than Bellatrix.  The 2018 picture was taken in January with an iPhone, and it shows Betelgeuse to be brighter than Bellatrix, but the difference seems to have diminished.  And the December 2019 iPhone photo definitely shows Betelgeuse to now be about the same brightness as Bellatrix.  Also, at the beginning of the sequence, Betelgeuse is quite close to Rigel in brightness, while by 2019 it is clearly much dimmer. 

For additional reference, the other set of photos below shows a very good example of astrophotography of Orion (from Wiki) in comparison with the September 2016 iPad photo.

About Betelgeuse and Supernovas

Betelgeuse is a red giant star, about 11 or so solar masses, at a distance of about 700 light years.  It is a progenitor star for a supernova – in other words, it will end its “stellar life” in a supernova, to become a neutron star or a black hole.  This is expected to happen soon by astronomical standards, which means within about 100,000 years.

So, this could happen any day, or it might be a thousand centuries from now.  It is now thought that the star is too far from the Earth to actually pose a significant threat to life on our planet, even when it does go supernova.  However, it is expected to be a good show for anyone around at that time, as it will be at least as bright as the full moon, and probably even visible during the day.

It is natural to wonder whether the current unprecedented dimming is a warning that the star will soon explode (this is within the 100,000 year window, after all).  Basically, nobody really knows.
Supernovas are rare during the current galactic epoch, with maybe one expected within the Milky Way every century or so.  Only a couple have been observed in recorded history – the 10th century event that created the Crab Nebula and another in the 17th century.  Other than that, we have had to rely on observations of supernova in nearby galaxies, such as the event in 1987 in the Magellenic Cloud, a nearby “suburb” galaxy of the Milky Way. 

Because these events are so rare, we don’t have historical observations of what the progenitor star looks like in the period of a few years before it goes supernova.  So, we don’t know if it dims before the explosion or whether it first brightens.  Perhaps it pulsates for a few centuries (as Betelgeuse does now) before exploding.  Or maybe it just goes bang with no warning.

That leaves us with theory to try to predict what a star on its way to going supernova looks like.  The theory of the evolution of massive stars goes something like this:

“For the most massive stars…the carbon core remains convective and carbon burns to oxygen and magnesium.  Finally, the star consists of an iron core surrounded by shells with silicon, oxygen, carbon, helium and hydrogen.  The nuclear fuel is now exhausted, and the star collapses on a dynamical time scale.  The result is a supernova.  The other parts explode, but the remaining core continues to contract to a neutron star or a black hole.” (Page 253 of Fundamental Astronomy by Karttunen et al)

“For example, for a 20 solar mass star, its main-sequence lifetime (core hydrogen burning) is roughly 10 million years, core helium burning requires one million years, carbon burning lasts 300 years, oxygen burning takes roughly 200 days, and silicon burning is completed in only two days!” (page 510 of Modern Astrophysics by Carroll and Ostlie)

That doesn’t really pin things down much, in terms of what we might expect to witness when Betelgeuse does go supernova.

During these various stages, dust can be thrown off that could obscure the star from our point of view, or dust could be blown away by a solar wind giving us a better view.  And of course, the intensity of the nuclear burning of various fuels could brighten or dim the star.  To be sure about these matters, we would require more observations, hopefully close enough to learn a lot about supernovas but far enough away to remain safe. 

It is always worth keeping in mind that astrophysical theory says that our sun condensed out of an enormous nebula, that was probably created by a supernova over 5 billion years ago.  The heavy elements, some of which are needed for life on Earth, were created in that supernova.  So, in a sense we owe our existence to a supernova (we really are stardust), though we hope that we won’t owe our demise to the second coming of one.

Turning and turning in the widening gyre   
The falcon cannot hear the falconer;
Things fall apart; the centre cannot hold;
Mere anarchy is loosed upon the world,
The blood-dimmed tide is loosed, and everywhere   
The ceremony of innocence is drowned;
 (Yeats, The Second Coming)


·       The Astronomers’ Telegram
·       Fundamental Astronomy by Karttunen et al
·       Modern Astrophysics by Carroll and Ostlie
·       Wikipedia (Betelgeuse entry).
 Photo of Betelgeuse: ALMA [CC BY 4.0 (]

Some Related Blogs

The Orion Nebula

Related to astronomy (sort of), if you want to see an area that is remarkably evocative of the landscape of Mars, here on Earth, try Newfoundland’s Table Lands, as described in the book below (along with plenty of other interesting features of Newfoundland):

A Drive Across Newfoundland


Newfoundland, Canada’s most easterly province, is a region that is both fascinating in its unique culture and amazing in its vistas of stark beauty. The weather is often wild, with coastal regions known for steep cliffs and crashing waves (though tranquil beaches exist too). The inland areas are primarily Precambrian shield, dominated by forests, rivers, rock formations, and abundant wildlife. The province also features some of the Earth’s most remarkable geology, notably The Tablelands, where the mantle rocks of the Earth’s interior have been exposed at the surface, permitting one to explore an almost alien landscape, an opportunity available on only a few scattered regions of the planet.

The city of St. John’s is one of Canada’s most unique urban areas, with a population that maintains many old traditions and cultural aspects of the British Isles. That’s true of the rest of the province, as well, where the people are friendly and inclined to chat amiably with visitors. Plus, they talk with amusing accents and party hard, so what’s not to like?

This account focusses on a two-week road trip in October 2007, from St. John’s in the southeast, to L’Anse aux Meadows in the far northwest, the only known Viking settlement in North America. It also features a day hike visit to The Tablelands, a remarkable and majestic geological feature. Even those who don’t normally consider themselves very interested in geology will find themselves awe-struck by these other-worldly landscapes.

And now that you have read about some real cutting-edge science, you should think about reading some Science Fiction (because all work and no play can make you a dull person, or so they say).  This one includes a sequence where a neutron star plays an important role in the action.

The Witches' Stones, Book 1 - Rescue from the Planet of the Amartos

Young Earth woman and spaceship mechanic, Sarah Mackenzie, has unwittingly triggered a vast source of energy, the Witches' Stones, via her psychic abilities, of which she was unaware. She becomes the focal point of a desperate contest between the authoritarian galactic power, known as The Organization, and the democratic Earth-based galactic power, known as The Terran Confederation. The Organization wants to capture her, and utilize her powers to create a super-weapon; the Terra Confederation wants to prevent that at all costs. The mysterious psychic aliens, the Witches of Kordea also become involved, as they see her as a possible threat, or a possible ally, for the safety of their own world.
A small but fast scout-ship, with its pilot and an agent of the Terra Confederation, Coryn Leigh, are sent to rescue her from a distant planet at the very edge of the galaxy, near space claimed by The Organization.  Battles, physical and mental, whirl around the young woman, as the agent and pilot strive at all costs to keep her from the clutches of the Organization.

Monday, 9 December 2019

The eVscope – A new era in Astronomy for Light Polluted Skies

The eVscope – A new era in Astronomy for Urban Dwellers in Light Polluted Skies

There has been a recent paper published on the Acta Astronautica website about a telescope under development, that will soon be available to the public (depending on when you read this, it might already be available).  It is specifically designed to facilitate viewing from light polluted skies, a problem that exists for many observers.  This is called the eVscope.

The telescope is a Newtonian (reflector), with a 4.5 in (114.5 cm) aperture, so it isn’t really all that large, in terms of light gathering power.  However, it has a low-light CMOS sensor at the prime focus, essentially an electronic camera.  That sensor captures multiple frames of an image, using exposure times of between 1 millisecond and 4 seconds.  An onboard computer then stacks and processes these frames - the usual processing that you might do with an astrophotography program is done automatically to improve the image.  This all produces an image that is projected through the electronics eyepiece.  Though the setup is designed to mimic dark sky viewing, the data can also be accessed by the user in TIFF format, so that additional processing and analysis can be performed.

The telescope also contains an algorithm to find and identify stars and deep sky objects, based on a large internal map in memory.  In that sense, it is a goto telescope with embedded data that can also can display the relevant information right on the viewing screen (i.e. through the eyepiece) as shown in the photo from the paper. 

So, it is intended to make it easy to find and to identify objects, two obstacles to observing that get in the way of many observers enjoyment.  Though learning how to star-hop and such can be its own reward, it can be quite tedious, time-consuming and frustrating for anyone who is not quite dedicated; this helps users to spend more time observing and less time searching. 

  The objects in the telescopes database include:

  1. Planets and the moon
  2. Messier objects (all 110)
  3. Thousands of NGC objects (at least 7840 of them)
  4. Thousands of smaller solar system objects, such as asteroids and dwarf planets.

The ease of use of the telescope, along with its embedded data handling should enable the data from each scope to be used for scientific work, yielding a sort of citizen science crowd-sourcing of astronomic observations.  That could enhance the study of transient events as well as helping keep a global watch on possibly dangerous bodies that could wreak havoc on the Earth due to a collision.

The paper gives some examples of the eVscope’s scientific possibilities, including light curves from occultations, such as this occultation of a 13th magnitude star by Pluto.

The eVscope is supposed to be available to the public soon, by early 2020.  It won’t be cheap – their website is currently advertising $2999 U.S., with a delivery data of summer 2020, according to this screenshot.  If the reviews of the product hold up, it looks very tempting. 



Unistellar eVscopes: Smart, portable, and easy-to-use telescopes for exploration, interactive learning, and citizen astronomy,  Acta Astronautica 166 (2020) 23–28
Franck Marchis , Arnaud Malvachea, Laurent Marfisia, Antonin Borota, Emmanuel Arboucha
Unistellar, 19 Rue Vacon 13001 Marseille, France
SETI Institute, Carl Sagan Center, 189 Bernardo Avenue, Suite 200, Mountain View, CA, USA

eVscope Website:
And if $3000 is a bit too much, here are a couple of short science fiction stories that you might want to try for only 99 cents.

The Zoo Hypothesis or The News of the World: A Science Fiction Story

In the field known as Astrobiology, there is a research program called SETI, The Search for Extraterrestrial Intelligence.  At the heart of SETI, there is a mystery known as The Great Silence, or The Fermi Paradox, named after the famous physicist Enrico Fermi.  Essentially, he asked “If they exist, where are they?”.

Some quite cogent arguments maintain that if there was extraterrestrial intelligence, they should have visited the Earth by now. This story, a bit tongue in cheek, gives a fictional account of one explanation for The Great Silence, known as The Zoo Hypothesis.  Are we a protected species, in a Cosmic Zoo?  If so, how did this come about?  Read on, for one possible solution to The Fermi Paradox.

The short story is about 6500 words, or about half an hour at typical reading speeds.

The Magnetic Anomaly: A Science Fiction Story

“A geophysical crew went into the Canadian north. There were some regrettable accidents among a few ex-military who had become geophysical contractors after their service in the forces. A young man and young woman went temporarily mad from the stress of seeing that. They imagined things, terrible things. But both are known to have vivid imaginations; we have childhood records to verify that. It was all very sad. That’s the official story.” 

The short story is about 6000 words, or about half an hour at typical reading speeds.