Night Sky

Published on by Catherine Toulsaly

Venus and the Moon (December 28)

Venus and the Moon (December 28)

A slumber did my spirit seal;
I had no human fears:
She seemed a thing that could not feel
The touch of earthly years.

No motion has she now, no force;
She neither hears nor sees;
Rolled round in earth's diurnal course,
With rocks, and stones, and trees.

William Wordsworth

 

Driving southeast from Cleveland on the first month of the year, the night curtains fall, revealing dazzling stars and planets caught in a net of constellations. The starlights beam bright, but I am not sure how I feel and whether they trigger in me some “distant memory” *. Venus, the third brightest celestial body, shines in the southwest sky. Beyond the heliosphere, eruptive, unstable stars signal their dramatic demise. Energy shocks flow in space when stars eject mass in a bubble of whimsical clouds as if they were “pulsating”. Mass loss may produce planetary nebulae such as NGC 5307 in the Centaurus constellation and  NGC 2022  in Orion. Those phenomena emit ultraviolet light that causes the expelled gases to glow. 

NGC 5307 (ESA/Hubble & NASA, R. Wade et al.; CC BY 4.0)

NGC 5307 (ESA/Hubble & NASA, R. Wade et al.; CC BY 4.0)

NGC 2022 (ESA/Hubble & NASA, R. Wade et al.; CC BY 4.0)

NGC 2022 (ESA/Hubble & NASA, R. Wade et al.; CC BY 4.0)

 

My night sky is not the skies over Aotearoa, that the Maori people would have contemplated. According to the star map drawn by Garry Beckstrom for 43 degrees north latitude, as I was leaving Cleveland and crossing back the Chesapeake Bay watershed, the brightest stars, visible with a naked eye, were Procyon, Sirius, Rigel, and Capella. Stars are classified based on their magnitude and luminosity.  However, for an observer looking at the night sky, their apparent brightness is also relative to how close they are to the solar system like Sirius born in the outer segment of the Sagittarius-Carina arm in our Milky Way at 8.6 light-years away and Procyon at 11.4.  I see space stretching in a line up of globular or galactic clusters, a grid of star formations extending one after the other as the discovery of Gaia 1 cluster concealed from sight by the brightness of Sirius has shown. 

Night Sky
Hertzsprung–Russell diagram

Hertzsprung–Russell diagram

 

There are stars we can’t see, masked by the ones closer and brighter. Stars may outshine their companions, too. More than half of all stars are born and live out their long lives with other siblings making up so-called binary and multiple star systems. A hidden white dwarf was found hanging around with Sirius, and, in the constellation Canis Minor, a faint white dwarf was discovered keeping company to Procyon. Rigel, a massive blue supergiant in the Orion constellation,  is composed of at least four stars and Capella, of two binary pairs. Betelgeuse has no “invisible companion”** and forms the winter Triangle with Procyon and Sirius. However, a study published four years ago raised the possibility of a past coalescence with a companion star, making it harder for us to predict Betelgueuse’s evolutionary history and future. 

Betelgueuse (ESA/Herschel/PACS/L. Decin et al)

Betelgueuse (ESA/Herschel/PACS/L. Decin et al)

A few years back, a composite color image of Betelgeuse captured by the Herschel Space Telescope showed material ejected from Betelgeuse as it evolved into a red supergiant star, shaped by its bow shock interaction with the interstellar medium. In my mind, I picture Betelgeuse to be currently blocked by some obscuring material on the edge of an interstellar cloud.  Stars hide in a cocoon of gas and dust.  In 1847, there was a large erratic outburst now known as “The Great Eruption”. Eta Carinae, the subject of over four centuries of observations, dramatically faded. It was later established that the system was a massive, long-period, highly eccentric binary in which periodic variations are driven by the collision of the stellar winds of the component stars. A study published last year proposed that the long-term brightening phase, due to the dissipation of a dusty clump in front of the central star, will be completed around 2032 ± 4 yr, when the star will be brighter than in the 1600’s

 

 NGC 1175 (NASA/ESA Hubble Space Telescope and William Keel (University of Alabama) and the Galaxy Zoo team)

NGC 1175 (NASA/ESA Hubble Space Telescope and William Keel (University of Alabama) and the Galaxy Zoo team)

 

At nightfall, the ground slowly disappears. Under the starry dome, I paint with a Baudelairian brush the Universe. What looks to me like dust and smoke moving and spreading in various forms and shapes cloak galaxies like NGC 1175. Clumps of space dust formed the building blocks of terrestrial planets. A recent paper published in the Journal Nature reports of a population of dust-enshrouded objects orbiting the center of the Milky Way.

Star-forming molecular clouds are threaded by magnetic fields that are likely inherited from the galactic-scale interstellar medium out of which they condensed

Mark R. Krumholz and Christoph Federrath

One could read the history of galaxy mergers as a story of war and peace, filling space with ghosts and deceased stars. With my eyes closed, I could even sense a lingering feeling of bitterness at having been treated so unmercifully as hope vanishes in dark matter halos. 

… the one thing certain about bitterness is its blindness.

Martin Luther King, Jr, Where do we go from here?, p.26

 

 

Galaxies like egg-like structures are surrounded by a hot galactic corona beyond which another layer, a dark matter halo, is home of satellite galaxies. They are like islands in an archipelago  In the local group, the largest galaxy is Andromeda (M31) on collision course with the Milky Way. and the biggest satellite to orbit our own is the Large Magellanic Cloud (LMC), a face-on galaxy with low metallicityOver the course of its history, the Milky Way has ingested multiple smaller satellite galaxies. Satellites may clash with each other or fall in the Milky Way’s territory, quenching, as a result, star formation within their own galactic realm. It was suggested that a merger between the Milky Way and a dwarf galaxy named Gaia-Enceladus occurred between 11.6 and 13.2 Gyr ago.

The Universe 11 billion years ago (NASA, ESA, M. Kornmesser)

The Universe 11 billion years ago (NASA, ESA, M. Kornmesser)

 

It seems to me that stellar physics attempts to explain stars from inside out and the transitioning process from one state to the next.  An abundance of surveys, imaging techniques as well as astrometry and interferometry are tools used to provide a better understanding. Night and day skies are worlds apart like a butterfly and a mole. The difference is the stars that we cannot see. And for the human eyes, the only ones that they see are within one galaxy, the Milky Way, like a glistening carriage carrying us through the Universe.  

 

Between the naked branches of slumbered trees, the Moon is high as I walked through the park one morning.  The cold swishing breeze moves through the dead leaves still hanging on trees. Steady steps on the sidewalks, I feel the warmth of the blinding sun and the quiescence of the moment. Time is my friend.  Early the next morning, the Moon has not risen yet, still hiding under a blanket of earthly feathers after a bitterly cold day yesterday. Blinded by the Sun, she will rise later and later until the end of January. Shrouded in the dust of ignorance, my mind somehow wanders back to cosmic rays and the phantom divide. 

Photograph of the Milky Way in the night sky over Black Rock Desert, Nevada by Steve Jurveston

Photograph of the Milky Way in the night sky over Black Rock Desert, Nevada by Steve Jurveston

 

*Cosmos, Carl Sagan

**The lost planets, John Wenz

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