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The Variable Nebula NGC 2261

https://apod.nasa.gov/apod/image/2501/HubblesVariablecopy1024.jpg The Variable Nebula NGC 2261

The interstellar cloud of dust and gas captured in this
sharp telescopic snapshot is seen to change its appearance
noticeably over periods as short as a few weeks.

Discovered over 200 years ago and cataloged as NGC 2261,
bright star R Monocerotis lies at the tip of the fan-shaped nebula.

About one light-year across and 2500 light-years away, NGC 2261 was studied
early last century by astronomer Edwin Hubble and
the mysterious cosmic cloud is now more famous as
Hubble's Variable Nebula.

So what makes Hubble's nebula vary?

NGC 2261 is composed of a dusty reflection nebula
fanning out from the star R Monocerotis.

The leading variability explanation
holds that dense knots of obscuring dust pass close to R Mon
and cast moving shadows
across the dust clouds in the rest of Hubble's Variable Nebula.

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Hydrogen Clouds of M33

https://apod.nasa.gov/apod/image/2501/M33_1024.jpg Hydrogen Clouds of M33

Gorgeous spiral galaxy Messier 33 seems to have more than its
fair share of glowing hydrogen gas.

A prominent member of the local group of galaxies, M33 is also
known as the Triangulum Galaxy and
lies a mere 3 million light-years away.

The galaxy's central 60,000 light-years or so are shown in this sharp galaxy portrait.

The portrait features M33's reddish ionized hydrogen clouds or HII regions.

Sprawling along loose spiral arms that wind toward the core, M33's giant HII regions
are some of the largest known stellar nurseries,
sites of the formation of short-lived but very massive stars.

Intense ultraviolet radiation from the luminous, massive stars ionizes
the surrounding hydrogen gas and ultimately produces the
characteristic red glow.

In this image, broadband data were combined
with narrowband data recorded through a filter that
transmits the light of the strongest visible hydrogen and oxygen emission lines.

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APOD: 2025 January 29 – Dust Shells around WR 140 from Webb

https://apod.nasa.gov/apod/image/2501/Wr140Rings_Webb_960_2023.jpg APOD: 2025 January 29 – Dust Shells around WR 140 from Webb What are those strange rings?

Rich in dust, the rings are likely 3D shells --
but how they were created remains a topic of research. Where they were created is well known: in a binary star system that lies about 6,000 light years
away toward the constellation of the Swan (Cygnus) --
a system dominated by the Wolf-Rayet star WR 140. Wolf-Rayet stars are massive, bright, and known for their tumultuous winds.

They are also known for creating and dispersing heavy elements such as carbon,
which is a building block of interstellar dust.

The other star in the binary is also bright and massive -- but not as active.

The two great stars joust in an oblong orbit as they approach each other about every eight years.

When at closest approach, the X-ray emission from the system increases, as, apparently,
does the dust expelled into space -- creating another shell.

The featured infrared image by the Webb Space Telescope resolves greater details and more dust shells than ever before.

Images taken over consecutive years show the shells moving outward.

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Shell Galaxies in Pisces

https://apod.nasa.gov/apod/image/2411/NGC474_S1_Crop1024.jpg Shell Galaxies in Pisces This spectacular
intergalactic skyscape features Arp 227,
a curious system of galaxies from the 1966 Atlas of Peculiar Galaxies.

Some 100 million light-years distant
within the boundaries of the constellation Pisces,
Arp 227 consists of the two galaxies prominent
above and left of center, the shell galaxy NGC 474
and its blue, spiral-armed neighbor NGC 470.

The readily apparent shells and star streams of NGC 474 are likely tidal features
originating from the accretion
of another smaller galaxy during close gravitational encounters
that began over a billion years ago.

The large galaxy on the bottom righthand side of the deep image,
NGC 467, appears to be surrounded by faint shells and streams too,
evidence of another merging galaxy system.

Intriguing background galaxies are scattered around
the field that also includes spiky foreground stars.

Of course, those stars lie well within our own Milky Way Galaxy.

The telescopic field of view spans 25 arc minutes or just under 1/2 degree on the sky.

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APOD: 2024 November 6 – Comet Tsuchinshan Atlas over the Dolomites

https://apod.nasa.gov/apod/image/2411/CometA3Dolomites_Masi_960.jpg APOD: 2024 November 6 – Comet Tsuchinshan Atlas over the Dolomites Comet Tsuchinshan-Atlas is now headed back to the outer Solar System.

The massive dusty snowball put on quite a show during its trip near the Sun,
resulting in many impressive pictures from planet Earth during October.

The featured image was taken in mid-October and shows a
defining visual feature of the comet -- its impressive anti-tail.

The image captures Comet C/2023 A3 (Tsuchinshan–ATLAS) with impressively long dust and ion tails pointing up and away from the Sun, while the strong anti-tail --
composed of more massive dust particles --
trails the comet and points down and (nearly) toward the recently-set Sun.

In the foreground is village of Tai di Cadore, Italy,
with the tremendous Dolomite Mountains in the background.

Another comet, C/2024 S1 (ATLAS), once a candidate to
rival Comet Tsuchinshan-Atlas in brightness, broke up last week during its close approach to our Sun.

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Rigel and the Witch Head Nebula

https://apod.nasa.gov/apod/image/2410/Strega_apod_1024r.jpg Rigel and the Witch Head Nebula

By starlight, this eerie visage shines in the dark
with a crooked profile evoking its popular name, the Witch Head Nebula.

In fact, this entrancing telescopic portrait
gives the impression that
a witch has fixed her gaze on Orion's bright supergiant star Rigel.

More formally known as IC 2118,
the Witch Head Nebula spans about 50 light-years and
is composed of interstellar dust grains reflecting Rigel's starlight.

The color of the Witch Head Nebula is caused not only by Rigel's
intense blue light, but because the dust grains scatter blue light more efficiently than red.

The same physical process
causes Earth's daytime
sky
to appear blue, although the scatterers in
Earth's atmosphere are molecules of nitrogen and oxygen.

Rigel and this dusty cosmic crone are about 800 light-years away.

You may still see a few witches in your neighborhood tonight though,
so have a safe and Happy Halloween!

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Though I can’t offer shelter to the man sleeping on the footpath,
Nor hand a book to the child working in a nearby mill,
Though I can’t feed the disabled man who lost his hand and family in an accident,
Or bring color to the life of the blind child living nearby,

I can’t console the rickshaw driver struggling to support his family,
Nor buy all the balloons from the woman selling them with her sick child on her hip.
I can’t give sweets to the child outside the shop, watching me buy treats.

So, is Diwali truly happy?
Is it, if I can’t bring joy to those who truly need it?

Where is my humanity, my empathy, my community?
What does it mean to celebrate even a single day of happiness if I ignore suffering the rest?

Is Diwali really happy?

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NGC 7293: The Helix Nebula

https://apod.nasa.gov/apod/image/2410/NGC7293_preview1024.png NGC 7293: The Helix Nebula

A mere seven hundred light years from Earth toward the constellation Aquarius,
a star is dying.

The once sun-like star's last few thousand years have produced the Helix Nebula.

Also known as NGC 7293,
the cosmic Helix is
a well studied and nearby example of a Planetary Nebula,
typical of this final phase of stellar evolution.

Combining narrow band data from emission lines of hydrogen atoms
in red and oxygen atoms in blue-green hues,
this deep image shows tantalizing details
of the Helix, including its bright inner region
about 3 light-years across.

The white dot at the Helix's center is this Planetary Nebula's hot, dying central star.

A simple looking nebula at first glance,
the Helix is now understood to have a surprisingly complex geometry.

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