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Do (8*0.75 - hyd)/8 (how much hydrogen is still present in the core in percentages) |
And then 1 - (8*0.75 - hyd)/8 ( how much helium is present in the core in precentages) |
The space around the star will be "filled" with energy and some kg? of helium and hydrogen (due to gas emission)?. |
As you can see, I didn't need to calculate intermediate reaction to come up with this conclusion, it might not be accurate but it's good enough for a game :wink: |
The question now is how to calculate how much hydrogen a star fuses to helium per year. Maybe this can be solved by using E = mc2 ? We know the stars luminosity, that's E.. now what ? |
Last edited: Jun 16, 2015 |
16. Jun 16, 2015 #15 |
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Science Advisor |
Here's a quick, roughly approximate way to do it: |
Find on the wiki the total energy production in a single instance of fusion (the 4H->He mass defect), should be somewhere in the fusion or the p-p chain article. |
Calculate how many hydrogen atoms get fused into helium atoms per second to maintain the luminosity. You'll have to convert between units. |
And voilà. You have a function that converts hydrogen into helium per time unit. |
It's not going to win you any awards for accurate modelling, but maybe it'll do for your particular needs. |
Let us know should you get stuck. |
17. Jun 16, 2015 #16 |
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Staff: Mentor |
Oh, my mistake. That's not what I meant by a 'side reaction'. Those are the actual steps in the P-P chain. For what you're wanting I don't think they even need to be calculated now that I think about it. |
It depends on the star and the cycle of its life its in. Space certainly isn't filled with energy unless your just talking about the light output. Most stars have some sort of stellar wind, and high mass/post main sequence stars can eject immense amounts of material: https://en.wikipedia.org/wiki/Stellar_wind |
Post-main-sequencestars nearing the ends of their lives often eject large quantities of mass in massive ( 89598b72950903093a9bba3f6c6bd790.png solar masses per year), slow (v = 10 km/s) winds. These include red giants and supergiants, and asymptotic giant branch stars. These winds are understood to be driven by radiation pressure on dust condensing in the upper atmosphere of the stars. |
Stellar winds from main-sequencestars do not strongly influence the evolution of lower mass stars such as the Sun. However, for more massive stars such as O stars, the mass loss can result in a star shedding as much as 50% of its mass whilst on the main sequence: this clearly has a significant impact on the later stages of evolution. |
18. Jun 17, 2015 #17 |
Right. Theres no need to to calculate all that since the output is always the same. |
Found a powerpoint explaining all that, but I don't understand half of it, but no worries, I don't need that yet. |
I got stuck just by reading your comment.. I don't even know how to convert between units, I'm an economics student programming a scientific game so excuse me if I don't understand most of the scientific calculationso0). |
I found this article on the forum but I don't understand some parts either, I belive that Garth's replay has everything I need but I don't know how to apply my data on it. |
Last edited: Jun 17, 2015 |
19. Jun 17, 2015 #18 |
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Science Advisor |
O.k., let me help you along. |
One full p-p or CNO chain fuses 4 H nuclei into a He nucleus with the release of 26 MeV (mega electronvolts) of energy. |
A star has luminosity L (your input variable). Luminosity uses units of power, so it's energy/second. |
To maintain it, N number of fusion chains must be completed per second so that: |
##L =N * 26 MeV / 1 sec## |
You need to match the units of energy there, so covert whatever you get the luminosity in into MeV (or the other way around). If you get L in Watts, divide it by 1.6*10^-13. If you get L in terms of solar luminosity (L☉), multiply it by 3.85*10^26 to get Watts, then convert to MeV as before. |
Taking the Sun as an example, L☉=1 |
##N \approx 9*10^{37}## reactions every second. |
Every second 4*N hydrogen atoms turn into N helium atoms. |
If you take every star to be born with 75% H and 25% He by mass, the initial number of available atoms of each of the elements is just a function of mass. |
You'll then have a function that each second reduces the number of H by 4N and adds 1N of He. You just need to find out how many atoms of H and He are there in the first place: |
Take the mass of a star M. If in units of solar mass, convert to grams by multiplying by 2*10^33. In each gram there will be approximately NH atoms of hydrogen: |
##N_H / 1 g = 3/4*N_A/A_{rH}## |
where NA is the Avogadro's constant and ArH is the atomic weight of hydrogen. |
For helium, correspondingly: |
##N_{He} / 1 g = 1/4*N_A/A_{rHe}## |
Multiply those by the total mass in grams to get the total number of atoms. The atomic weights may just as well be taken to be 1 for H and 4 for He here. |
(somebody care to check for cock-ups, be my guest) |
You start with those numbers and deduct/add 4N/1N every second. |
Notice how both the number of atoms and luminosity are functions of mass, so that in the end that is the sole variable which determines the evolution of composition over time. |
Let me know if something's not clear. |
Last edited: Jun 17, 2015 |
20. Jun 17, 2015 #19 |
This will take me a while to understand, I'll post back once I test all this. |
21. Jun 17, 2015 #20 |
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Science Advisor |
Note there was a mistake in the last two equations. Now corrected. |
Don't hesitate to ask for clarifications. It's not terribly well presented as it is. |
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Sunday, January 9 |
Let His Light So Shine |
I was somewhere a few days ago and heard the song "Carry Your Candle" playing. The first time I had ever heard it was about a year ago on the radio, and the lyrics have stuck with me ever since... and remind me of the ability and call I have to share the light. |
Frustrated brother, see how he's tried to light his own candle another way... |
See now your sister - she's been robbed and lied to - still holds a candle without a flame. |
As the words pass by, I envision countless people, each tightly gripping a candle in his hand, trying to find his way and stay warm in a cold, dark night. The sea of darkness is interrupted only with rare and tiny pinpricks of light. And then I see me, holding in my hand a candle, topped by a tiny flame. Why me? How is it that somehow it worked out and I learned the truth of the gospel? How have I stayed alive when so many others have given up and let the flame die? And, in a world where everyone seems to be searching for peace and hope, why does God answer my prayers and keep me safe when I am surrounded by the storm? |
I think that at least part of the answer lies in the calling I've felt - the need to share the light - to run to the darkness to seek out the helpless, tired, and worn. Perhaps I needed to learn to give to others, to open my mouth, to trust Him when everything seems to be going wrong. There are days when I feel like my life is going nowhere, when I look around me and the only light I see is the pinprick of my faith in God... And then I look out at my brothers, each living a different life and fighting different battles... without even the pinprick that I hold in my hand... and I realize how blessed I am to have it. |
Some days I wish I could be an angel - to have the power to speak and to shake the earth and call men to repentance... to give the world hope in the peace that comes from living the gospel and no other way. And sometimes I can. Here on (Gay) Mormon Guy I can share my testimony, and hope that the Spirit will carry my words to the far reaches of the world and light a flame to last for eternity. People from Thailand and India, Africa and Saudi Arabia, Korea, China, and almost every country in between have found the message here... and I am amazed by the stories they send. |
But, most of the time, I walk through the darkness with only my own candle... and when I find a brother who will listen, I take him in my arms, share the light of my candle, and watch as he goes through life changed forever, sharing the light that has become a part of who he is. Most of those people have actually been girls, since I have trouble making friends with guys. |
That's the heart of who I want to be and what I want to accomplish - to somehow mold my life to reflect the light of the Savior and show His mercy and love to those who are searching in darkness. |
And hopefully it will help my own search. Part of my trial in life is feeling alone. I can be in a room of people who love me, surrounded by those who admire and esteem me, or even confiding my heart to a friend, and I still feel alone. I find myself looking for warmth from others, instead of turning to my candle of faith and my relationship with God. But when I share the gospel, and a brother borrows the light I have been given to relight his faith, for a moment, the candles flare... and I feel at home. For a moment, I can see and feel clearly into eternity, and God's glory fills my soul with light. |
1. Thanks GMG for all you do, |
I know what you mean by solitude in a crowded room, even with those I consider my best friends I feel... unknown... I was gonna say distant, but "unknown" better describes how it feels... I cherish their understanding and friendship, maybe it's just that I never feel like I could go to them and cry on their shoulder like I feel like doing sometimes... I'm not sure... |
I know at least one of them reads this occasionally and I'll probably have to explain this to him in more detail later... |
I have a few projects I've been working on to try to share my candle better where I am... and I definitely agree, I know that no matter how small and insignificant my contributions may be, they are a help to someone... |
2. Thanks for posting. Your blog seems so sincere and honest and I really appreciate your willingness to be so open. Undoubtedly, Father loves you dearly....Its nice to see that you know it! |
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Gray whales in Los Cabos: An expedition with style |
Cristopher Guevara / May 27, 2016 |
Things to do |
As every year, Los Cabos is the home of gray whales that migrate from far away in order to complete its reproductive cycle in the waters of the Pacific Ocean. These species travel more than 16,000 kilometers from Polar Arctic Circle through the coasts of Alaska, Canada, northern United States and California until they reach this warm destination. |
For the tourists to watch grey whales is an fantastic experience because these creatures use to approach boats, get their head above water, splash, jump and lift its tail to greet the passengers. You can only acquire this tour through tourism services providers. |
These giant mammals measure about 15 meters of height and have a weight of 30 tonnes, while baby whales measure between 4 and 5 meters with a weight of 750 kilos. In the South Californian sea you can also see other species such as turtles, dolphins, sea lions, and migratory birds like herons, ducks and gulls. |
The whale watching is a magical experience especially if a mother whale approaches the boat with its babies. To admire these animals is a unique opportunity that you can’t miss. The season to enjoy this show begins in December and ends in April, and the expedition usually starts at 8:00 a.m. |
If you’re a technology manager you need to move jobs roughly every five years to avoid being seen as a job-hopper or a plodder writes Jennifer Foreshew in The Australian’s IT section: Don’t job hop, IT managers told. |
She says younger technology workers should look at moving on every two to three years. |
For more on this see How long should I stay in a job? |
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Monday, August 18, 2014 |
BFI hunts for missing A Study in Scarlet (1914). |
Ad for the 1914 American version of |
A Study in Scarlet, starring Francis Ford |
Kelly Robinson said... |
I'm confounded as to why articles keep referring to this as the first Sherlock Holmes film. The first I know of was in 1903. There were at least a half-dozen more before this one comes into play—including some that Conan Doyle assisted with. |
Elizabeth Foxwell said... |
I was thinking that it might have something to do with length, but I see that "The Copper Beeches," "Mystery of Boscombe Valley," and "The Musgrave Ritual" (all 1912) are all 2-reelers, just like the Francis Ford version of "A Study in Scarlet." Perhaps people think that because "A Study in Scarlet" is the first Holmes in print, it must be the first film as well. |
North Carolina stands in for Scotland during `the games' |
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