APOD: Alpha Centauri: The Closest Star System (2025 Jan 01)

[APOD Robot]

Alpha Centauri: The Closest Star System

Explanation: The closest star system to the Sun is the Alpha Centauri system. Of the three stars in the system, the dimmest -- called Proxima Centauri -- is actually the nearest star. The bright stars Alpha Centauri A and B form a close binary as they are separated by only 23 times the Earth- Sun distance - slightly greater than the distance between Uranus and the Sun. The Alpha</a< Centauri star <a href="ap121018.html">system is not visible in much of the northern hemisphere. Alpha Centauri A, also known as Rigil Kentaurus, is the brightest star in the constellation of Centaurus and is the fourth brightest star in the night sky. Sirius is the brightest even though it is more than twice as far away. By an exciting coincidence, Alpha Centauri A is the same type of star as our Sun, and Proxima Centauri is now known to have a potentially habitable exoplanet.

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[SpaceCadet]

It is unclear from the explanation what is shown in the photo. Is this a photo of Proxima, Alpha A, or of Alpha B? Or is this the whole star system even though it appears there is only one star?

[RocketRon]

>>>and Proxima Centauri is now known to have a potentially habitable exoplanet.

Is it too early to book tickets on the next flight. ?

HAPPY NEW YEAR. !!
Its a brave new world out there ...

[Ann]

>>>and Proxima Centauri is now known to have a potentially habitable exoplanet.

Is it too early to book tickets on the next flight. ?
HAPPY NEW YEAR. !!
Its a brave new world out there ...

I am the owner of this book:

Beyond the Solar System.jpg

In the foreword of this book, William Ley wrote:

The first chapter (of this book) predicts and describes a manned expedition to the sun's nearest neighbor, the stellar system of Alpha Centauri in the southern sky. I think that such an expedition will be made at a time when people now alive (though very young) will be able to watch the take-off on television — say, half a century from now.

That book was printed in 1964. Half a century from 1964 was in 2014. We are late for our journey to Alpha Centauri!

Ann

[Ann]

It is unclear from the explanation what is shown in the photo. Is this a photo of Proxima, Alpha A, or of Alpha B? Or is this the whole star system even though it appears there is only one star?

The bright star in the picture is Alpha Centauri A+B. The two components are too close together to be separated in a photo like this. Proxima is quite far away from Alpha Centauri A+B, and Proxima is very faint indeed.

Alpha Centauri: The Closest Star System. Image Credit & Copyright: Telescope Live, Heaven's Mirror Observatory; Processing: Chris Cantrell

---

This is our best picture of Alpha Centauri A+B:

Alpha Centauri A (left) and Alpha Centauri B (right). Credit: ESA/Hubble & NASA

---

This is a two filter image, where the filters were a blue one (at 457 nm) and an infrared one (at 850 nm), so the colors look a bit weird. Alpha Centauri A is bluer than Alpha Centauri B, but Alpha Centauri B is more infrared than Alpha Centauri A. It is hard to see in the image that Alpha Centauri B is fainter than Alpha Centauri A.


I like these three pictures from ESO:

Alpha Centauri A+B and Proxima Centauri. Credit: ESO.

---

The first picture, the one at left, gives you an idea of the brightness difference between Alpha Centauri A+B and Proxima Centauri. The second image, at top right, gives you an idea of the sizes and separation between Alpha Centauri A and Alpha Centauri B. Note! The two stellar components are nowhere near as close together as the illustration makes you believe.

Wikipedia wrote about Alpha Centauri A and Alpha Centauri B:

Their elliptical orbit is eccentric, so that the distance between A and B varies from 35.6 astronomical units(AU), or about the distance between Pluto and the Sun, to 11.2 AU, or about the distance between Saturn and the Sun.

The third image shows Proxima Centauri.

Wikipedia wrote:

Proxima Centauri is the nearest star to Earth after the Sun, located 4.25 light-years away in the southern constellation of Centaurus. This object was discovered in 1915 by Robert Innes. It is a small, low-mass star, too faint to be seen with the naked eye, with an apparent magnitude of 11.13. Its Latin name means the 'nearest [star] of Centaurus'. Proxima Centauri is a member of the Alpha Centauri star system, being identified as component Alpha Centauri C, and is 2.18° to the southwest of the Alpha Centauri AB pair. It is currently 12,950 AU (0.2 ly) from AB, which it orbits with a period of about 550,000 years.

This would seem to be the orbit of Proxima around Alpha Centauri A+B (pardon my French):

Orbit of Proxima Centauri. Credit: © Pierre Kervalla / ESO/ Digitized Sky Survey2 / David de Martin / Mahdi Zamani / Observatoire de Paris

---

Proxima Centauri is a puny star indeed:

Wikipedia wrote:

Alpha Centauri C, better known as Proxima Centauri, is a small main-sequence red dwarf of spectral class M6-Ve. It has an absolute magnitude of +15.60, over 20,000 times fainter than the Sun. Its mass is calculated to be 0.1221 M_☉.

You may note that Alpha Centauri A+B looks blue in the last picture I posted. By contrast, it looks orange in the APOD. The truth is that Alpha Centauri A+B is just a little yellower than the Sun. My point of view is that the Sun is white, because it is white to our eyes. But surely the Sun is yellow to our eyes? No, because the color of the daylight that reaches us is the combined color of all the visible sunlight that reaches us. This color is white (or neutral).

I visited a cool installation in Copenhagen a few years ago, where they showed the color of the clear daylight sky (which is blue), ███, and the color of the Sun minus the sky (which is yellowish), ███, and the color of the Sun plus the color of the sky, which is white or neutral, like this: ███.

So if the color of Alpha Centauri is a little yellower than the Sun, its color might be something like this: ███.

Let's look at a comparison of the sizes of Alpha Centauri A, Alpha Centauri B, the Sun, Proxima Centauri and also Sirius. D1E5F4

Relative sizes of the Alpha Centauri components and other objects (artist’s impression). Credit: ESO

---

Please note! I must warn you against believing in the colors, both the "relative colors" and the "absolute colors" of the stars in this illustration.

No way Sirius is yellow-white in color!!! In my opinion, its color may be described as this, ███. Can't you see it against the blue background? Well, the color is a very pale shade of blue!

As for "relative colors", the Sun is whiter than both Alpha Centauri A and Alpha Centauri B. Alpha Centauri B is a very pale shade of peach or maybe banana, ███, whereas Alpha Centauri A can be described as pale lemon, ███.

Actually, I think that the colors of Alpha Centauri A and Alpha Centauri B look good in the illustration, but the Sun looks far too yellow!

Ann

[Christian G.]

A nice image focussed on one single STAR, pure and simple, is a perfect way to start the New Year!

AlphaCen_Cantrell_3429.jpg

As for our puny neighbour Proxima Centauri, here's a bigger view:

Proxima Cemtauri.jpg

Hubble

[johnnydeep]

A nice image focussed on one single STAR, pure and simple, is a perfect way to start the New Year!
AlphaCen_Cantrell_3429.jpg

As for our puny neighbour Proxima Centauri, here's a bigger view:
Proxima Cemtauri.jpg
Hubble

But that single star is a binary!

[Christian G.]

A nice image focussed on one single STAR, pure and simple, is a perfect way to start the New Year!
AlphaCen_Cantrell_3429.jpg

As for our puny neighbour Proxima Centauri, here's a bigger view:
Proxima Cemtauri.jpg
Hubble

But that single star is a binary!

Your eyesight is better than mine!

[AVAO]

A nice image focussed on one single STAR, pure and simple, is a perfect way to start the New Year!
AlphaCen_Cantrell_3429.jpg

As for our puny neighbour Proxima Centauri, here's a bigger view:
Proxima Cemtauri.jpg
Hubble

But that single star is a binary!

Your eyesight is better than mine!

The APOD is annotated, but unfortunately Alpha Centauri A & B in the middle are not. This is a bit confusing. Alpha Centauri C = Proxima Centauri is very, very, very far away from this star duo in the middle by stellar standards and I personally doubt that they really form a triple system as in the title as the "Alpha Centauri Star System":

"However, recent studies indicate that Proxima Centauri forms a moving group together with the Alpha Centauri double star system and nine other star systems. Proxima Centauri does not orbit the Alpha Centauri pair in a bound motion, but experiences a hyperbolic perturbation of its orbit due to this pair. In other words, Proxima Centauri will never complete a full orbit around Alpha Centauri A and B. (ESO News No. 05/03 of March 15, 2003)"

In my opinion, Proxima Centauri is more of a loner star that is only temporarily our closest star. As a so-called flare star, it is also very, very moody.

"Proxima Centauri falls into the category of flare stars because its brightness rises above average from time to time due to magnetic activity. Because of its low mass, the interior of the star is completely convective (the heat generated is transported outwards by plasma currents, not by radiation). Convection is associated with the generation and transport of a stellar magnetic field. At the surface, the magnetic energy of this field is released by flares, which can more than double the overall brightness of the star. This corresponds to an increase in brightness of about one magnitude. These flares can grow to the size of the star and reach temperatures of up to two million Kelvin. Due to this high temperature, they can emit X-rays with an intensity similar to that of the sun. (Wikipedia ger)"

"Proxima Centauri has been the closest star to the sun for 32,000 years and will remain so for another 30,000 years until it is replaced by Ross 248. Ross 248 is a red, cool dwarf star and belongs to the group of UV Ceti stars and is therefore very energetic. Due to its high speed, however, it will only hold this title for about 9,000 years. Since the Voyager 2 space probe is flying roughly in the direction of Ross 248, it will reach its closest orbital point to this red dwarf, 1.7 light years away, in about 40,000 years. (Wikipedia ger)"

Be relaxed – everything is relative

[SpaceCadet]

It is unclear from the explanation what is shown in the photo. Is this a photo of Proxima, Alpha A, or of Alpha B? Or is this the whole star system even though it appears there is only one star?

The bright star in the picture is Alpha Centauri A+B. The two components are too close together to be separated in a photo like this. Proxima is quite far away from Alpha Centauri A+B, and Proxima is very faint indeed.

Alpha Centauri: The Closest Star System. Image Credit & Copyright: Telescope Live, Heaven's Mirror Observatory; Processing: Chris Cantrell

---

This is our best picture of Alpha Centauri A+B:

Alpha Centauri A (left) and Alpha Centauri B (right). Credit: ESA/Hubble & NASA

---

This is a two filter image, where the filters were a blue one (at 457 nm) and an infrared one (at 850 nm), so the colors look a bit weird. Alpha Centauri A is bluer than Alpha Centauri B, but Alpha Centauri B is more infrared than Alpha Centauri A. It is hard to see in the image that Alpha Centauri B is fainter than Alpha Centauri A.


I like these three pictures from ESO:

Alpha Centauri A+B and Proxima Centauri. Credit: ESO.

---

The first picture, the one at left, gives you an idea of the brightness difference between Alpha Centauri A+B and Proxima Centauri. The second image, at top right, gives you an idea of the sizes and separation between Alpha Centauri A and Alpha Centauri B. Note! The two stellar components are nowhere near as close together as the illustration makes you believe.

Wikipedia wrote about Alpha Centauri A and Alpha Centauri B:

Their elliptical orbit is eccentric, so that the distance between A and B varies from 35.6 astronomical units(AU), or about the distance between Pluto and the Sun, to 11.2 AU, or about the distance between Saturn and the Sun.

The third image shows Proxima Centauri.

Wikipedia wrote:

Proxima Centauri is the nearest star to Earth after the Sun, located 4.25 light-years away in the southern constellation of Centaurus. This object was discovered in 1915 by Robert Innes. It is a small, low-mass star, too faint to be seen with the naked eye, with an apparent magnitude of 11.13. Its Latin name means the 'nearest [star] of Centaurus'. Proxima Centauri is a member of the Alpha Centauri star system, being identified as component Alpha Centauri C, and is 2.18° to the southwest of the Alpha Centauri AB pair. It is currently 12,950 AU (0.2 ly) from AB, which it orbits with a period of about 550,000 years.

This would seem to be the orbit of Proxima around Alpha Centauri A+B (pardon my French):

Orbit of Proxima Centauri. Credit: © Pierre Kervalla / ESO/ Digitized Sky Survey2 / David de Martin / Mahdi Zamani / Observatoire de Paris

---

Proxima Centauri is a puny star indeed:

Wikipedia wrote:

Alpha Centauri C, better known as Proxima Centauri, is a small main-sequence red dwarf of spectral class M6-Ve. It has an absolute magnitude of +15.60, over 20,000 times fainter than the Sun. Its mass is calculated to be 0.1221 M_☉.

You may note that Alpha Centauri A+B looks blue in the last picture I posted. By contrast, it looks orange in the APOD. The truth is that Alpha Centauri A+B is just a little yellower than the Sun. My point of view is that the Sun is white, because it is white to our eyes. But surely the Sun is yellow to our eyes? No, because the color of the daylight that reaches us is the combined color of all the visible sunlight that reaches us. This color is white (or neutral).

I visited a cool installation in Copenhagen a few years ago, where they showed the color of the clear daylight sky (which is blue), ███, and the color of the Sun minus the sky (which is yellowish), ███, and the color of the Sun plus the color of the sky, which is white or neutral, like this: ███.

So if the color of Alpha Centauri is a little yellower than the Sun, its color might be something like this: ███.

Let's look at a comparison of the sizes of Alpha Centauri A, Alpha Centauri B, the Sun, Proxima Centauri and also Sirius. D1E5F4

Relative sizes of the Alpha Centauri components and other objects (artist’s impression). Credit: ESO

---

Please note! I must warn you against believing in the colors, both the "relative colors" and the "absolute colors" of the stars in this illustration.

No way Sirius is yellow-white in color!!! In my opinion, its color may be described as this, ███. Can't you see it against the blue background? Well, the color is a very pale shade of blue!

As for "relative colors", the Sun is whiter than both Alpha Centauri A and Alpha Centauri B. Alpha Centauri B is a very pale shade of peach or maybe banana, ███, whereas Alpha Centauri A can be described as pale lemon, ███.

Actually, I think that the colors of Alpha Centauri A and Alpha Centauri B look good in the illustration, but the Sun looks far too yellow!

Ann

Thank you for this in depth explanation!

[johnnydeep]

But that single star is a binary!

Your eyesight is better than mine!

The APOD is annotated, but unfortunately Alpha Centauri A & B in the middle are not. This is a bit confusing. Alpha Centauri C = Proxima Centauri is very, very, very far away from this star duo in the middle by stellar standards and I personally doubt that they really form a triple system as in the title as the "Alpha Centauri Star System":

"However, recent studies indicate that Proxima Centauri forms a moving group together with the Alpha Centauri double star system and nine other star systems. Proxima Centauri does not orbit the Alpha Centauri pair in a bound motion, but experiences a hyperbolic perturbation of its orbit due to this pair. In other words, Proxima Centauri will never complete a full orbit around Alpha Centauri A and B. (ESO News No. 05/03 of March 15, 2003)"

In my opinion, Proxima Centauri is more of a loner star that is only temporarily our closest star. As a so-called flare star, it is also very, very moody.

"Proxima Centauri falls into the category of flare stars because its brightness rises above average from time to time due to magnetic activity. Because of its low mass, the interior of the star is completely convective (the heat generated is transported outwards by plasma currents, not by radiation). Convection is associated with the generation and transport of a stellar magnetic field. At the surface, the magnetic energy of this field is released by flares, which can more than double the overall brightness of the star. This corresponds to an increase in brightness of about one magnitude. These flares can grow to the size of the star and reach temperatures of up to two million Kelvin. Due to this high temperature, they can emit X-rays with an intensity similar to that of the sun. (Wikipedia ger)"

"Proxima Centauri has been the closest star to the sun for 32,000 years and will remain so for another 30,000 years until it is replaced by Ross 248. Ross 248 is a red, cool dwarf star and belongs to the group of UV Ceti stars and is therefore very energetic. Due to its high speed, however, it will only hold this title for about 9,000 years. Since the Voyager 2 space probe is flying roughly in the direction of Ross 248, it will reach its closest orbital point to this red dwarf, 1.7 light years away, in about 40,000 years. (Wikipedia ger)"

Be relaxed – everything is relative

Wikipedia says there is evidence now that Proxima is gravitationally bound to the AB binary.

Alpha Centauri C is about 13,000 AU (0.21 ly; 1.9×1012 km) from Alpha Centauri AB, equivalent to about 5% of the distance between Alpha Centauri AB and the Sun.[17][57][69] Until 2017, measurements of its small speed and its trajectory were of too little accuracy and duration in years to determine whether it is bound to Alpha Centauri AB or unrelated.

Radial velocity measurements made in 2017 were precise enough to show that Proxima Centauri and Alpha Centauri AB are gravitationally bound.[17] The orbital period of Proxima Centauri is approximately 511000+41000
−30000 years, with an eccentricity of 0.5, much more eccentric than Mercury's. Proxima Centauri comes within 4100+700
−600 AU of AB at periastron, and its apastron occurs at 12300+200
−100 AU.[5]

[Christian G.]

>>>and Proxima Centauri is now known to have a potentially habitable exoplanet.

Is it too early to book tickets on the next flight. ?
HAPPY NEW YEAR. !!
Its a brave new world out there ...

I am the owner of this book:


Beyond the Solar System.jpg


In the foreword of this book, William Ley wrote:

The first chapter (of this book) predicts and describes a manned expedition to the sun's nearest neighbor, the stellar system of Alpha Centauri in the southern sky. I think that such an expedition will be made at a time when people now alive (though very young) will be able to watch the take-off on television — say, half a century from now.

That book was printed in 1964. Half a century from 1964 was in 2014. We are late for our journey to Alpha Centauri!

Ann

We're late but not out of time, Proxima Centauri should shine on that exoplanet for another FOUR TRILLION YEARS! Or 300 times the current age of the universe!

[Ann]

>>>and Proxima Centauri is now known to have a potentially habitable exoplanet.

Is it too early to book tickets on the next flight. ?
HAPPY NEW YEAR. !!
Its a brave new world out there ...

I am the owner of this book:


Beyond the Solar System.jpg


In the foreword of this book, William Ley wrote:

The first chapter (of this book) predicts and describes a manned expedition to the sun's nearest neighbor, the stellar system of Alpha Centauri in the southern sky. I think that such an expedition will be made at a time when people now alive (though very young) will be able to watch the take-off on television — say, half a century from now.

That book was printed in 1964. Half a century from 1964 was in 2014. We are late for our journey to Alpha Centauri!

Ann

We're late but not out of time, Proxima Centauri should shine on that exoplanet for another FOUR TRILLION YEARS! Or 300 times the current age of the universe!

Right! We have all the time in the world (and then some)!!

Ann

[Ann]

I've got to show you a mystery I found in the APOD, and then the solution to the mystery. There seemed to be a strange orange nebula southeast of cluster NGC 5617:

APOD 1 January 2025.png

What was that thing? I searched in vain for any info on it. But the Simbad Astronomical Database closeup of nearby cluster NGC 5617 revealed the identity of the orange blob. It is a reddened star cluster! Fancy that!

Red star cluster southeast of NGC 5617.png

Reddened star cluster southeast of NGC 5617.
Credit: SDSS.

What's the name of that star cluster? Dunno. Simbad wouldn't tell me.

Ann

[johnnydeep]

I've got to show you a mystery I found in the APOD, and then the solution to the mystery. There seemed to be a strange orange nebula southeast of cluster NGC 5617:


APOD 1 January 2025.png


What was that thing? I searched in vain for any info on it. But the Simbad Astronomical Database closeup of nearby cluster NGC 5617 revealed the identity of the orange blob. It is a reddened star cluster! Fancy that!

Red star cluster southeast of NGC 5617.png

Reddened star cluster southeast of NGC 5617.
Credit: SDSS.

What's the name of that star cluster? Dunno. Simbad wouldn't tell me.

Ann

Ok, now what's the even larger irregular red smudge at about 6 o'clock from Alpha Centuri, near the bottom of the APOD?

[AVAO]

I've got to show you a mystery I found in the APOD, and then the solution to the mystery. There seemed to be a strange orange nebula southeast of cluster NGC 5617:


APOD 1 January 2025.png


What was that thing? I searched in vain for any info on it. But the Simbad Astronomical Database closeup of nearby cluster NGC 5617 revealed the identity of the orange blob. It is a reddened star cluster! Fancy that!

Red star cluster southeast of NGC 5617.png

Reddened star cluster southeast of NGC 5617.
Credit: SDSS.

What's the name of that star cluster? Dunno. Simbad wouldn't tell me.

Ann

Ok, now what's the even larger irregular red smudge at about 6 o'clock from Alpha Centuri, near the bottom of the APOD?

Good question. It's RCW 86 (SNR 185).
Nice cosmic bundle of nerves ,-)

Click to view full size image

Original Data: NASA/ESA composit jac berne (flickr)
viewtopic.php?t=42978#p329564

[AVAO]

I've got to show you a mystery I found in the APOD, and then the solution to the mystery. There seemed to be a strange orange nebula southeast of cluster NGC 5617:


APOD 1 January 2025.png


What was that thing? I searched in vain for any info on it. But the Simbad Astronomical Database closeup of nearby cluster NGC 5617 revealed the identity of the orange blob. It is a reddened star cluster! Fancy that!

Red star cluster southeast of NGC 5617.png

Reddened star cluster southeast of NGC 5617.
Credit: SDSS.

What's the name of that star cluster? Dunno. Simbad wouldn't tell me.

Ann

Ask APOD - It's Pismis 19 ,-) Jac

Click to view full size image

https://apod.nasa.gov/apod/ap120628.html

Masterclass

Henize 2-111: https://app.astrobin.com/i/3qh2c7

[johnnydeep]

I've got to show you a mystery I found in the APOD, and then the solution to the mystery. There seemed to be a strange orange nebula southeast of cluster NGC 5617:


APOD 1 January 2025.png


What was that thing? I searched in vain for any info on it. But the Simbad Astronomical Database closeup of nearby cluster NGC 5617 revealed the identity of the orange blob. It is a reddened star cluster! Fancy that!

Red star cluster southeast of NGC 5617.png

Reddened star cluster southeast of NGC 5617.
Credit: SDSS.

What's the name of that star cluster? Dunno. Simbad wouldn't tell me.

Ann

Ok, now what's the even larger irregular red smudge at about 6 o'clock from Alpha Centuri, near the bottom of the APOD?

Good question. It's RCW 86 (SNR 185).
Nice cosmic bundle of nerves ,-)

Click to view full size image

Original Data: NASA/ESA composit jac berne (flickr)
viewtopic.php?t=42978#p329564

Nice - thanks! Your image looks quite different from the first one in Wikipedia. I'm guessing your red image is the blue portion shown in Wikipedia (though my attempts to recognize the correct overlay has often been wrong)?

Infrared images from NASA's Spitzer Space Telescope and WISE are combined with X-ray data from the Chandra X-ray Observatory and ESA's XMM-Newton Observatory in this image

---

[AVAO]

Ok, now what's the even larger irregular red smudge at about 6 o'clock from Alpha Centuri, near the bottom of the APOD?

Good question. It's RCW 86 (SNR 185).
Nice cosmic bundle of nerves ,-)

Click to view full size image

Original Data: NASA/ESA composit jac berne (flickr)
viewtopic.php?t=42978#p329564

Nice - thanks! Your image looks quite different from the first one in Wikipedia. I'm guessing your red image is the blue portion shown in Wikipedia (though my attempts to recognize the correct overlay has often been wrong)?

Infrared images from NASA's Spitzer Space Telescope and WISE are combined with X-ray data from the Chandra X-ray Observatory and ESA's XMM-Newton Observatory in this image

---

That's right. The whole SNR is much larger. But in today's APOD only the enlarged part can be seen as a small red nebula.

Click to view full size image

Original data: NASA/ESA composit jac berne (flickr)

[johnnydeep]

Good question. It's RCW 86 (SNR 185).
Nice cosmic bundle of nerves ,-)

Click to view full size image

Original Data: NASA/ESA composit jac berne (flickr)
viewtopic.php?t=42978#p329564

Nice - thanks! Your image looks quite different from the first one in Wikipedia. I'm guessing your red image is the blue portion shown in Wikipedia (though my attempts to recognize the correct overlay has often been wrong)?

Infrared images from NASA's Spitzer Space Telescope and WISE are combined with X-ray data from the Chandra X-ray Observatory and ESA's XMM-Newton Observatory in this image

---

That's right. The whole SNR is much larger. But in today's APOD only the enlarged part can be seen as a small red nebula.

Click to view full size image

Original data: NASA/ESA composit jac berne (flickr)

I see - Thanks!

[Ann]

I've got to show you a mystery I found in the APOD, and then the solution to the mystery. There seemed to be a strange orange nebula southeast of cluster NGC 5617:


APOD 1 January 2025.png


What was that thing? I searched in vain for any info on it. But the Simbad Astronomical Database closeup of nearby cluster NGC 5617 revealed the identity of the orange blob. It is a reddened star cluster! Fancy that!

Red star cluster southeast of NGC 5617.png

Reddened star cluster southeast of NGC 5617.
Credit: SDSS.

What's the name of that star cluster? Dunno. Simbad wouldn't tell me.

Ann

Ask APOD - It's Pismis 19 ,-) Jac

Click to view full size image

https://apod.nasa.gov/apod/ap120628.html

Masterclass

Henize 2-111: https://app.astrobin.com/i/3qh2c7

Thanks, Jac, I should have thanked you before! Did you just search the APOD archive to find the designation of this cluster?

That's a glorious APOD by Marco Lorenzi, by the way. Around 2012 may have been the peak of beautiful, detailed, highly resolved and fantastically RGB-colored astrophotography!

Ann

[AVAO]

I've got to show you a mystery I found in the APOD, and then the solution to the mystery. There seemed to be a strange orange nebula southeast of cluster NGC 5617:


APOD 1 January 2025.png


What was that thing? I searched in vain for any info on it. But the Simbad Astronomical Database closeup of nearby cluster NGC 5617 revealed the identity of the orange blob. It is a reddened star cluster! Fancy that!

Red star cluster southeast of NGC 5617.png

Reddened star cluster southeast of NGC 5617.
Credit: SDSS.

What's the name of that star cluster? Dunno. Simbad wouldn't tell me.

Ann

Ask APOD - It's Pismis 19 ,-) Jac

Click to view full size image

https://apod.nasa.gov/apod/ap120628.html

Masterclass

Henize 2-111: https://app.astrobin.com/i/3qh2c7

Thanks, Jac, I should have thanked you before! Did you just search the APOD archive to find the designation of this cluster?

That's a glorious APOD by Marco Lorenzi, by the way. Around 2012 may have been the peak of beautiful, detailed, highly resolved and fantastically RGB-colored astrophotography!

Ann

ThanX Ann

I agree with you. Did you see the link above to the Astrobin image of Henize 2-111 by Wolfgang Promper?
His Astrobin page, his galaxy portraits and also his image of the planetary nebula Henize 2-111 are outstanding.
https://www.astrobin.com/users/Wolfgang-Promper/
Unfortunately, he has never selected one of his images for an APOD, although for me he is one of the top astrophotographers in the world.
search.php?keywords=Wolfgang+Promper&fid%5B0%5D=29
"Click to view full size image" if you see broken image links.

With 165 submitted top images I'm almost ashamed of that.

Jac

[Ann]

Ask APOD - It's Pismis 19 ,-) Jac

Click to view full size image

https://apod.nasa.gov/apod/ap120628.html

Masterclass

Henize 2-111: https://app.astrobin.com/i/3qh2c7

Thanks, Jac, I should have thanked you before! Did you just search the APOD archive to find the designation of this cluster?

That's a glorious APOD by Marco Lorenzi, by the way. Around 2012 may have been the peak of beautiful, detailed, highly resolved and fantastically RGB-colored astrophotography!

Ann

ThanX Ann

I agree with you. Did you see the link above to the Astrobin image of Henize 2-111 by Wolfgang Promper?
His Astrobin page, his galaxy portraits and also his image of the planetary nebula Henize 2-111 are outstanding.
https://www.astrobin.com/users/Wolfgang-Promper/
Unfortunately, he has never selected one of his images for an APOD, although for me he is one of the top astrophotographers in the world.
search.php?keywords=Wolfgang+Promper&fid%5B0%5D=29
"Click to view full size image" if you see broken image links.

With 165 submitted top images I'm almost ashamed of that.

Jac

I saw his picture of Henize 2-111, and it is great indeed!

And thanks for the links to all those great Wolfgang Promper images. I particularly remember being impressed by his "Mermaid Nebula", posted here at Starship Asterisk on April 29 last year!

Ann