Starship Asterisk*

Amazing display on Friday night from Cornwall in the South-West of the UK. The pillars were bright rapidly changing, in subtle greens, purples and occasionally blue. Didn't know where to look at times, there were some bright transient features due South. Brightest display here for over 20 years I b...

the location of sunspots on the Sun is not random. https://www.rmg.co.uk/sites/default/files/styles/large_no_alt/public/2022-08/A%20Year%20in%20the%20Sun%20by%20Soumyadeep%20Mukherjee%20-%20Astronomy%20Photographer%20of%20the%20Year%202022%20Our%20Sun.jpg?itok=Y-_vrDSh Ann seems rather like one of ...

Neither black hole lost mass. The individual precursor black holes merged to form a new black hole, and it has a higher mass than either of the precursors. The total mass difference reflects the conversion of gravitational potential energy (as the two precursors got closer) into kinetic energy, and...

Hello everybody, I have a question about the BHs' masses. I imagined that nothing could escape from a BH (except perhaps by Hawking radiation) but it seems that part of the mass of a couple of merging BHs is radiated as GW. I suspect that the energy emitted as GW comes from the kinetic/gravitationa...

While the bare physics have to be right, and the simulation flawless, I was underwhelmed by the video - surely such an event will be accompanied by more fireworks, with accretion disks and jets exploding? And thank you to Ann for telling me of the "Final Parsec Problem". I found this: &qu...

I wonder how to tell Wiki to edit all ly to kly at the right side of this infographics from 15 April 2021 about the companions to the Event Horizon Telescope's April 2017 campaign:

I wonder why this version failed to gain popularity

The singularity is small (infinitesimal) but isn't the BH's "size" and hence the gravitational effect - and collision window - determined by how large the event horizon is? A black hole's "gravitational effect" is determined by its mass. The event horizon isn't a real thing, jus...

IMHO this APOD means that the star is going away moving the other way than suggested in the comments above. The accretion disk has been dark but now there is a bright trail through it; we can't see the disk in this pic, just the glowing trail through it. What makes me think that the exit is broad ha...

I searched in vain on the ESO site for an annotated overall map of the VLTI facility but came up empty. But google was my friend. Sadly though, the - much! - smaller R2D2-like ATs on their tracks aren't labeled, but are clear to see in the lower parts of the photo: https://www.eso.org/sci/facilitie...

Once again a masterpiece! Congratulations to the Deep Sky Collective team. Be sure to click twice on the image to see the Nova up close, gorgeous object! I like cosmic dandelions too! ...and when you overlay older images (e.g. from Hubble) you can clearly see how the nova is developing... https://l...

I just told you that I don't necessarily always trust Wikipedia, but now I'm going to quote Wikipedia anyway to back up my claim that there are two bars in NGC 1365: And I can see the bars of NGC 1365. :wink: Ann Is there even a definition of a "bar" based on something other than mere app...

I still find the area very exciting even in IR. https://live.staticflickr.com/65535/53692377213_263792ee09_b.jpg jac berne (SSDS/GLIMPSE) https://live.staticflickr.com/65535/53691271482_756c52c430_b.jpg jac berne (SSDS/SPITZER) I wonder why does SSDS fish have a collar (just like APOD fish does) an...

In context from a wider field of view image at one of the links in the text: fish head, heart, and soul nebulas.jpg I still find the area very exciting even in IR. https://live.staticflickr.com/65535/53692377213_263792ee09_b.jpg jac berne (SSDS/GLIMPSE) https://live.staticflickr.com/65535/536912714...

I think, regardless of the observer's distance to the object, its width, in light-years, is static. I.E. Q:"How tall is Snowman?" A: 2 meters Q: I've doubled my viewing distance from Snowman; now how tall is Snowman? A: 2 meters But in order to determine that the snowman is 2 meters high,...

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and a fragment

Ah. It's a shame these diagrams don't all use the same standard scales. Well, personally I prefer to use Gaia data. these are standardized and used in the same way for many analyzes. Here are 25 April 2018 Gaia — More than four million stars within five thousand light-years from the Sun 10 August 2...

Exactly. Which reasonably suggests that they have entirely different formation processes. The HR diagram of the Milky Way..jpgThe HR diagram of the Milky Way-.jpg https://asterisk.apod.com/download/file.php?id=49545&mode=view Cool! Nice work. Well I am not sure. Maybe fitting the temperature sc...

Some globular clusters have central black holes. I think there are at least two differences. A globular cluster has a different radial density gradient than a galaxy. And a globular cluster has a very different HR diagram than a galaxy, indicating a different formation process. https://upload.wikim...

Let's start with my Chandra portrait of NGC 604: APOD 25 April 2024 annotated.png Possible location of the Chandra bubbles in the APOD. Maybe it's just the right-hand bubble that is seen in the Chandra image. https://chandra.harvard.edu/photo/2009/n604/n604_labeled_525.jpg Chandra X-ray Observatory...

fit to my eye a blue (OIII, right?) jellyfish swimming rightward from the star breakes the bipolarity

Contrail Shadow X (2024 Apr 23)-.jpg I'm not sure what the lines in your image are intended to demonstrate. To me, they don't make it any clearer that the contrail shadows are being cast down onto the clouds, not upwards. only that the sun is well above the horizon in this APOD; but that's enough t...

I agree with others here that we are seeing the shadows of the contrails cast down onto the clouds, not up. (I'm not convinced it's even possible to have a contrail shadow cast up onto a cloud... the Sun would have to be on or slightly below the horizon, and I think the directly illuminated cloud w...

I agree with others here that we are seeing the shadows of the contrails cast down onto the clouds, not up. (I'm not convinced it's even possible to have a contrail shadow cast up onto a cloud... the Sun would have to be on or slightly below the horizon, and I think the directly illuminated cloud w...

This is a classical optical illusion: the cloud cover is lower than the contrails and thus the shadows are below. The low standing sun deceive the observer, because the observer places the plane in between the low standing sun and the shadows overhead (according to the relative altitudes above the ...