Starship Asterisk*

Globular Star Cluster NGC 6752

Explanation: Some 13,000 light-years away toward the southern constellation Pavo, the globular star cluster NGC 6752 roams the halo of our Milky Way galaxy. Over 10 billion years old, NGC 6752 follows clusters Omega Centauri, 47 Tucanae, and Messier 22 as the fourth brightest globular in planet Earth's night sky. It holds over 100 thousand stars in a sphere about 100 light-years in diameter. Telescopic explorations of NGC 6752 have found that a remarkable fraction of the stars near the cluster's core, are multiple star systems. They also reveal the presence of blue straggle stars, stars which appear to be too young and massive to exist in a cluster whose stars are all expected to be at least twice as old as the Sun. The blue stragglers are thought to be formed by star mergers and collisions in the dense stellar environment at the cluster's core. This sharp color composite also features the cluster's ancient red giant stars in yellowish hues. (Note: The bright, spiky blue star about 8 o'clock from the cluster center is a foreground star along the line-of-sight to NGC 6752)

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APOD Robot wrote: ↑Fri Oct 25, 2024 4:06 am Globular Star Cluster NGC 6752

Bedin 1 in NGC 6752: ZOOM:https://esahubble.org/images/heic1903b/zoomable/
CREDIT: NASA/ESA

AVAO wrote: ↑Fri Oct 25, 2024 5:19 am

APOD Robot wrote: ↑Fri Oct 25, 2024 4:06 am Globular Star Cluster NGC 6752

Bedin 1 in NGC 6752:

Click to view full size image

ZOOM:https://esahubble.org/images/heic1903b/zoomable/
CREDIT: NASA/ESA

Thanks, Jac, I remember the dwarf galaxy behind the globular, but I had no idea that the photobombing globular was NGC 6752!

Don't want to use up one more of my attachments, but I can't help myself:


I hate those white "wings" of both sides of the picture - you get those on every Hubblesite image - but please just look at the contrast between Bedin 1 and the bright and much more distant edge-on spiral galaxy to the upper left of it! There sure are creatures big and small in the great garden of the Universe.

Wikipedia wrote about Bedin 1:

Bedin I is a dwarf spheroidal galaxy located in the constellation Pavo. It is situated around 28.38 million light-years from Earth, behind the globular cluster NGC 6752. Bedin I is possibly one of the oldest galaxies known, having formed around 10–13 billion years ago, and is one of the most isolated dwarf galaxies known, situated around 2.12 million light-years away from NGC 6744, its nearest neighbor with which it may be physically associated. As such, it has been deemed by astronomers as a "fossil" from the early universe...

It is estimated to be around 840 by 340 parsecs, or 2,700 by 1,100 light-years, in size, which is a fifth the size of the Large Magellanic Cloud.

Let's return to the APOD and my second attachment:


The "spiky blue star about 8 o'clock from the cluster center" that the caption talked about is HD 177999A or TYC 9071-2141-1. This star is spectral class B9, it is located some 1,100 light-years away from us, and its color and brightness makes it somewhat similar to Alioth, the brightest star in the Big Dipper's handle.


According to today's caption, there are blue stragglers in NGC 6752. It's certainly not surprising that we find blue stragglers in a globular cluster, where stars whiz past one another all the time and exchange speeds, orbits and also mass. Of course, for a mass tranfer to occur, the stars must be in very close proximity indeed, as in famous star Algol and its unlucky shrunken red giant partner.

Blue B8-type star Algol is a blue straggler, because it was originally less massive than it is today. It probably started out as a late A-type star or even an F-type star. Its more massive companion evolved into a swollen red giant, but when it did so, it filled its so called Roche lobe and started spilling mass onto its compact companion.

Ann

Whoa, how have I missed this one? It should be well visible from my latitude!

I think I know. It’s not visible from 40° north, so it’s not talked about.

Describe what the night sky would look like if our solar system was at or near the core of NGC 6752:

"If our solar system were near the core of NGC 6752, the night sky would appear vastly different, dominated by an extraordinary brightness from millions of nearby stars. The density of stars would eliminate any dark spaces, creating a constant, intense twilight. Stars would appear larger and brighter due to their proximity, some as close as 0.1 light-years, and the sky would be rich with vivid colors, especially deep reds, oranges, and yellows from aging red giants.

The sky would constantly change, with noticeable stellar movements over time and frequent alignments or encounters between stars, adding to its dynamism. Our familiar constellations would disappear, replaced by an overwhelming tapestry of light where patterns are nearly impossible to distinguish. Supernovae, though rare, would become occasional highlights, appearing as temporarily dominant features.

The Milky Way’s band would fade in prominence, replaced by the cluster’s stars, while zodiacal light might be more pronounced due to the interstellar medium. Increased radiation from nearby stars could heighten auroras, creating vibrant displays near magnetic poles.

Living near such a core would mean perpetual light-filled nights, potentially affecting life cycles and rhythms. The radiant, densely packed sky would offer a stunning yet overwhelming view of a crowded stellar metropolis, a constant reminder of the vastness and diversity of the universe."

Ann wrote: ↑Fri Oct 25, 2024 6:29 am

AVAO wrote: ↑Fri Oct 25, 2024 5:19 am

APOD Robot wrote: ↑Fri Oct 25, 2024 4:06 am Globular Star Cluster NGC 6752

...

Wikipedia wrote about Bedin 1:

Bedin I is a dwarf spheroidal galaxy located in the constellation Pavo. It is situated around 28.38 million light-years from Earth, behind the globular cluster NGC 6752. Bedin I is possibly one of the oldest galaxies known, having formed around 10–13 billion years ago, and is one of the most isolated dwarf galaxies known, situated around 2.12 million light-years away from NGC 6744, its nearest neighbor with which it may be physically associated. As such, it has been deemed by astronomers as a "fossil" from the early universe...

It is estimated to be around 840 by 340 parsecs, or 2,700 by 1,100 light-years, in size, which is a fifth the size of the Large Magellanic Cloud.

...

Wait a minute now. NGC 6752 is 13000 ly from us, and Bedin 1 is 28.38 Mly from us. Yet, NGC 6752 is only 2.12 Mly from Bedin 1? Something doesn't add up...

johnnydeep wrote: ↑Fri Oct 25, 2024 6:42 pm
Wait a minute now. NGC 6752 is 13000 ly from us, and Bedin 1 is 28.38 Mly from us. Yet, NGC 6752 is only 2.12 Mly from Bedin 1? Something doesn't add up...

It doesn't say that NGC 6752 is 2.12 Mly from Bedin 1.

Chris Peterson wrote: ↑Fri Oct 25, 2024 6:52 pm

johnnydeep wrote: ↑Fri Oct 25, 2024 6:42 pm
Wait a minute now. NGC 6752 is 13000 ly from us, and Bedin 1 is 28.38 Mly from us. Yet, NGC 6752 is only 2.12 Mly from Bedin 1? Something doesn't add up...

It doesn't say that NGC 6752 is 2.12 Mly from Bedin 1.

No? And I quote:

Bedin I is possibly one of the oldest galaxies known, having formed around 10–13 billion years ago, and is one of the most isolated dwarf galaxies known, situated around 2.12 million light-years away from NGC 6744

Am I reading this wrong?

[ EDIT: oh, never mind! It's a different NGC number! ]