|
Do red giants really look like they do in SpaceEngine?
|
|
| Watsisname | Date: Tuesday, 26.11.2013, 01:28 | Message # 46 |
 Galaxy Architect
Group: Global Moderators
United States
Messages: 2613
Status: Offline
| It does look strange, but there really is an astrophysical reason for it.  Giant stars have low surface gravities, so their outer convective envelopes are only loosely held. This makes them have enormous convective cells, like giant versions of the granules on our sun.
There was an earlier thread on this topic here, but the difference in thread title may explain why the search didn't find it.
Edit: Whoops, ninja'd by the Harbinger!
|
| |
| |
| dissembly | Date: Tuesday, 26.11.2013, 03:52 | Message # 47 |
 Observer
Group: Users
Australia
Messages: 13
Status: Offline
| Awesome, thank-you.
|
| |
| |
| Dustin432321 | Date: Friday, 20.06.2014, 03:46 | Message # 48 |
 Observer
Group: Newbies
United States
Messages: 3
Status: Offline
| I'm having this weird problem that make stars look distorted an bubbly looking. I have uninstalled and re-installed and to no avail nothing works.
merged from another thread
-Watsisname
Edited by Watsisname - Monday, 23.06.2014, 03:26 |
| |
| |
| Donatelo200 | Date: Friday, 20.06.2014, 05:02 | Message # 49 |
|
Explorer
Group: Users
United States
Messages: 261
Status: Offline
| What type of star are you looking at? If it is a red giant or any star of the giant class they will be lumpy and bubbly due to their low gravities. If this is the case then it is not a bug.
Betelgeuse as an example.
CPU: Intel Core i7-4790K
GPU: Nvidia GTX 1080
SSD: Samsung 850 Evo 250GB
HDD: Toshiba DT01ACA200 2TB
HDD: WD Blue 1TB (2012)
RAM: Unknown 16G-D3-1600-MR 2x8GB
MBD: MSI Z97S SLI Krait Edition (MS-7922)
|
| |
| |
| snowballpudi | Date: Monday, 23.06.2014, 02:12 | Message # 50 |
|
Space Tourist
Group: Users
United States
Messages: 21
Status: Offline
| Maybe the red giants could have some type of slow bubbling motion so they could look more animated or active.
|
| |
| |
| Castun | Date: Friday, 30.01.2015, 11:48 | Message # 51 |
|
Observer
Group: Newbies
United States
Messages: 2
Status: Offline
| Maybe I'm just generalizing but...
Is it just me or are all red giants & red hypergiants ugly misshapen blobs? They are also pretty dim, dim enough that you can easily see the large variations of color and height in their surface, even from a distance. Is it because they are unstable dying stars that are in the process of ejecting their mass and / or collapsing?
|
| |
| |
| apenpaap | Date: Friday, 30.01.2015, 11:58 | Message # 52 |
 World Builder
Group: Users
Antarctica
Messages: 1063
Status: Offline
| Quote Castun (  ) Is it because they are unstable dying stars that are in the process of ejecting their mass and / or collapsing?
That's precisely why they look like that. Red giants have an extremely low surface gravity due to their massive size, and as a result the large, hot convection cells in their envelope are thought to cause deformations to the star. Their dimness is simply an effect of their temperature; something 3000 degrees hot simply isn't going to be eyeblindingly white like our Sun.
I occasionally stream at http://www.twitch.tv/magistermystax. Sometimes SE, sometimes other games.
|
| |
| |
| Castun | Date: Friday, 30.01.2015, 12:47 | Message # 53 |
|
Observer
Group: Newbies
United States
Messages: 2
Status: Offline
| Neat, thanks.
So is the same true of all giants regardless of color class? I've noticed that even Blue & White giants have the same deformations, though not as extreme as a red, and tend to still be mostly spherical.
|
| |
| |
| HarbingerDawn | Date: Friday, 30.01.2015, 14:06 | Message # 54 |
 Cosmic Curator
Group: Administrators
United States
Messages: 8717
Status: Offline
| http://en.spaceengine.org/forum/0-0-0-36
http://en.spaceengine.org/forum/22-689-1
All forum users, please read this!
My SE mods and addons
Phenom II X6 1090T 3.2 GHz, 16 GB DDR3 RAM, GTX 970 3584 MB VRAM
|
| |
| |
| Watsisname | Date: Friday, 30.01.2015, 21:41 | Message # 55 |
|
Galaxy Architect
Group: Global Moderators
United States
Messages: 2613
Status: Offline
| ~merged thread~
Quote Castun ( ) So is the same true of all giants regardless of color class? I've noticed that even Blue & White giants have the same deformations, though not as extreme as a red, and tend to still be mostly spherical.
The extent of "bubbliness" of the surface is primarily a function of the star's surface gravity, so the more bloated and tenuous the star's outer layers are, the more weakly it holds on to them, and the larger the convection cells become. This tends to be most significant with the red giants and hyper-giants that have evolved far off the main sequence and really puffed themselves up.
|
| |
| |
| astroniki | Date: Friday, 22.05.2015, 19:43 | Message # 56 |
 Space Pilot
Group: SE team
Poland
Messages: 115
Status: Offline
| I found this really neat high resolution simulation of a red giant.
https://www.youtube.com/watch?v=Ys0hvi-5b_Q
Check out my astrophotography:
http://www.astroniki.fbl.pl
http://www.facebook.com/AstroNiki1
|
| |
| |
| Alek | Date: Thursday, 28.05.2015, 00:41 | Message # 57 |
 Pioneer
Group: Users
United States
Messages: 326
Status: Offline
| Honestly, the bubbliness wouldn't be that extreme, in my thinking. Or at least not enough to completely deform the star. Also, the luminosities of these stars can get humongous because of their large surface areas, so why AREN'T they brighter in SE?
Living among the stars, I find my way. I grow in strength through knowledge of the space I occupy, until I become the ruler of my own interstellar empire of sorts. Though The world was made for the day, I was made for the night, and thus, the universe itself is within my destiny.
|
| |
| |
| FastFourierTransform | Date: Thursday, 28.05.2015, 09:04 | Message # 58 |
 Pioneer
Group: Local Moderators
Spain
Messages: 542
Status: Offline
| Quote Alek ( ) the bubbliness wouldn't be that extreme, in my thinking
There are scientific papers with numerical simulations like this http://www.astro.uu.se/~bf/movie/dst35gm04n26/movie.html
and the bubbliness can be quite extreme.
|
| |
| |
| Watsisname | Date: Thursday, 28.05.2015, 09:55 | Message # 59 |
|
Galaxy Architect
Group: Global Moderators
United States
Messages: 2613
Status: Offline
| Yes, and not only does this behavior appear in simulations of giant stars, but it also agrees very well with observations.
Giant stars have giant convective cells. This was anticipated in the 1970s, before we could even do these sorts of simulations. It's a fairly simple consequence of their astrophysics.
Quote Alek ( ) Also, the luminosities of these stars can get humongous because of their large surface areas, so why AREN'T they brighter in SE?
Sure, luminosity is proportional to surface area, and temperature to the fourth power:
Giant stars are indeed extremely luminous, because their greater surface area more than overcomes their decreased surface temperature.
This is how SE models star luminosity by the way. So I'm curious what you think is wrong about it, or how you suggest it should be changed, or what math you have done to support your conclusion.
Now, if you mean how bright a giant star looks from close enough to resolve it, then you may be confusing "luminosity" with "surface brightness", or how much light is emitted per unit area of the surface. This does not depend on the star's size, only its temperature. It's the T4 term in that formula above. Again SE simulates surface brightness of stars according to this, what we call a blackbody spectrum.
|
| |
| |
| parameciumkid | Date: Saturday, 30.05.2015, 06:40 | Message # 60 |
 Explorer
Group: Users
United States
Messages: 277
Status: Offline
| ...This thread is funny. Every fifth post is someone coming in and going "The red giants look like misshapen blobs, is it a bug?" obviously without having read the rest of the thread and the repeated explanations that it's intentional xD
Intel HD Graphics 4000 ;P
|
| |
| |
ENG
New site
United States 
Australia 
Antarctica 
Poland 
Spain