Starship Asterisk*

[quote=Ann post_id=329940 time=1679383555 user_id=129702]
[img3="The Mystic Mountain in the Carina Nebula. Note how the jets seem to be rotating. Image Credit: NASA, ESA, M. Livio and the Hubble 20th Anniversary Team"]https://www.nasa.gov/sites/default/files/styles/full_width_feature/public/thumbnails/image/c92-2.jpg[/img3]
Ann
[/quote]

makes me wonder if this APOD does show an arc
[hide][attachment=0]TaurusDust_Chander_4096.png[/attachment][attachment=1]TaurusDust_Chander_4096+.png[/attachment][/hide]
[imghover=https://asterisk.apod.com/download/file.php?id=47138]https://asterisk.apod.com/download/file.php?id=47139[/imghover]

I immediately thought of a cephalopod when looking at the picture. Since we already have a Squid somewhere on the sky, maybe it's apt to nickname this one the Octopus nebula?

[img3="Dark Nebulae and Star Formation in Taurus. Image Credit & Copyright: Vikas Chander"]https://apod.nasa.gov/apod/image/2303/TaurusDust_Chander_1080.jpg[/img3]


When I first saw this APOD, I was stumped. Is this a picture of T Tauri and Hind's Variable Nebula? If so, where is the star and what sort of nebula is that?? 😮


[float=left][img3="Hubble's Variable Nebula, NGC 2261. Credit: HST/NASA/JPL/Judy Schmidt"]https://upload.wikimedia.org/wikipedia/commons/thumb/8/8b/Hubble%27s_Variable_Nebula_-_NGC_2261.png/330px-Hubble%27s_Variable_Nebula_-_NGC_2261.png[/img3][/float][float=right][img3="T Tauri and Hind's Variable Nebula, NGC 1555, in infrared. Credit: NASA/2MASS"]https://upload.wikimedia.org/wikipedia/commons/7/76/Ngc1555.jpg[/img3][/float]
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I thought Hubble's Variable Nebula looked like the image at left? Oh, sorry, you mean Hind's Variable Nebula? But seriously, where in today's APOD is the star and the nebula that resembles what you can see in the picture from 2MASS? Okay, today's caption solved the problem for us, with its [url=https://apod.nasa.gov/apod/ap220210.html]Hind's Variable Nebula[/url] link, which takes us to this picture (below, at left):


[float=left][img3="T Tauri and Hind's Variable Nebula. Image Credit & Copyright: Dawn Lowry, Gian Lorenzo Ferretti, Ewa Pasiak and Terry Felty"]https://apod.nasa.gov/apod/image/2202/NGC1555texas2021_1094.jpg[/img3][/float][float=right][attachment=2]Hinds variable nebula author unknown.png[/attachment][c][size=85][color=#0040FF]Hind's Variable Nebula. Author unknown.[/color][/size][/c][/float]
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So, I guess, problem solved! Though I must say that when I saw that strange bright round little nebula on a severely bent "body", I couldn't help thinking of a poor cat with its head trapped in a jar, violently shaking its head to try to get out of the jar!


[float=left][attachment=1]APOD 21 March 2023 detail annotated.png[/attachment][/float] [float=right][img3="Cat with its head stuck in a jar."]https://pictures-of-cats.org/wp-content/uploads/2021/06/Cat-gets-his-head-stuck-in-a-cookie-jar.jpg[/img3][/float]
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And indeed, Hind's Variable Nebula has formed at the edge of a dark dust lane inside a molecular cloud, and the entire construction seems top-heavy. I would guess that the star and its nebula are indeed rotating and precessing, in a way slightly similar to what we can see in the "Mystic Mountain" star forming region in the Carina Nebula:


[img3="The Mystic Mountain in the Carina Nebula. Note how the jets seem to be rotating. Image Credit: NASA, ESA, M. Livio and the Hubble 20th Anniversary Team"]https://www.nasa.gov/sites/default/files/styles/full_width_feature/public/thumbnails/image/c92-2.jpg[/img3]


Finally, note the patches of pink above and below the young, tempestuous and not fully formed star T Tauri:


[attachment=0]APOD 21 March 2023 detail arrows.png[/attachment]


I think, although I'm not quite certain, that these are Herbig-Haro objects. Perhaps they have been formed as T Tauri ejected jets into the surrounding molecular cloud to rid itself of excess rotational energy as it was accreting more matter onto itself, as young and not fully formed stars are wont do do.

Ann

[url=https://apod.nasa.gov/apod/ap230321.html] [img]https://apod.nasa.gov/apod/calendar/S_230321.jpg[/img] [size=150]Dark Nebulae and Star Formation in Taurus[/size][/url]

[b] Explanation: [/b] Can dust be beautiful? Yes, and it can also be useful. The [url=https://en.wikipedia.org/wiki/Taurus_molecular_cloud]Taurus molecular cloud[/url] has several bright stars, but it is the [url=https://apod.nasa.gov/apod/ap180626.html]dark dust[/url] that really [url=https://www.selfsufficientculture.com/attachments/cat-dog-chickens-looking-into-kitchen-through-window-jpeg.811/]draws attention[/url]. The pervasive [url=https://astronomy.swin.edu.au/cosmos/d/Dust+Grain]dust[/url] has waves and ripples and makes picturesque [url=https://www.thisoldhouse.com/21017966/anatomy-of-a-dust-bunny]dust[/url] [url=https://dailybunny.org/]bunnies[/url], but perhaps more importantly, it marks regions where [url=https://stardate.org/astro-guide/interstellar-gas-and-dust]interstellar gas[/url] is dense enough to [url=https://en.wikipedia.org/wiki/Gravitational_collapse]gravitationally contract[/url] to form stars. In the image center is a light cloud lit by neighboring stars that is home not only to a famous nebula, but to a very young and massive famous star. Both the star, [url=https://en.wikipedia.org/wiki/T_Tauri]T Tauri[/url], and the nebula, [url=https://apod.nasa.gov/apod/ap220210.html]Hind's Variable Nebula[/url], are seen to vary dramatically in brightness -- but not necessarily at the same time, adding to the mystery of this intriguing region. [url=https://apod.nasa.gov/apod/ap110326.html]T Tauri[/url] and [url=https://en.wikipedia.org/wiki/T_Tauri_star]similar stars[/url] are now generally recognized to be [url=https://spaceplace.nasa.gov/all-about-the-sun/]Sun[/url]-like stars that are less than a few million years old and so still in the early stages of [url=https://science.nasa.gov/astrophysics/focus-areas/how-do-stars-form-and-evolve]formation[/url]. The featured image spans about four [url=https://lco.global/spacebook/sky/using-angles-describe-positions-and-apparent-sizes-objects/]degrees[/url] not far from the [url=https://apod.nasa.gov/apod/ap221205.html]Pleiades[/url] star cluster, while the featured dust field lies about 400 [url=https://spaceplace.nasa.gov/light-year/]light-years[/url] away.


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