New Contender For Brightest Star?

[dragon04]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'><font><font><font face="arial" size="2"><font face="arial"><p class="MsoNormal"><span style="font-size:10pt;font-family:'Arial','sans-serif'">A known star has reemerged on the scene as the second brightest in our galaxy and may in fact be the brightest.</span></p> <p class="MsoNormal"><span style="font-size:10pt;font-family:'Arial','sans-serif'">The "Peony nebula star" shines as brightly as 3.2 million suns, but lurked in obscurity among interstellar gas and dust in the central region of the Milky Way &mdash; until now.</span></p> <p class="MsoNormal"><span style="font-size:10pt;font-family:'Arial','sans-serif'">NASA's Spitzer Space Telescope used infrared vision to scope out the star behind the Peony nebula's reddish cloud of dust. The European Southern Observatory's New Technology Telescope in Chile also used infrared vision to see the star's true power behind its dusty veil.</DIV></span></p></font></font></font></font><p>http://www.space.com/scienceastronomy/080716-bright-star.html</p><p>With this discovery, what impact might it have on the current estimates that astrophysics uses to attempt to explain the accelerating expansion of the Universe?</p><p>"Dark Energy" is very awkward. However, Spitzer, with its infrared spectacles is seeing what the eye cannot. How much more mass is there really in the Universe than conventional Astrophysics estimate? </p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>http://www.space.com/scienceastronomy/080716-bright-star.htmlWith this discovery, what impact might it have on the current estimates that astrophysics uses to attempt to explain the accelerating expansion of the Universe?"Dark Energy" is very awkward. However, Spitzer, with its infrared spectacles is seeing what the eye cannot. How much more mass is there really in the Universe than conventional Astrophysics estimate? &nbsp; <br /> Posted by dragon04</DIV></p><p>No impact at all.</p><p>Maybe I'm missing something, but I don't see how this discovery is in anyway connected to dark energy and accelerated expansion.</p><p>If it was a standard candle like a cephid variable or type Ia supernova that was far more luminous than expected, I can see asking these questions, but it's just another star that happens to be really, really big and hot.&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[dragon04]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>No impact at all.Maybe I'm missing something, but I don't see how this discovery is in anyway connected to dark energy and accelerated expansion.If it was a standard candle like a cephid variable or type Ia supernova that was far more luminous than expected, I can see asking these questions, but it's just another star that happens to be really, really big and hot.&nbsp; <br /> Posted by derekmcd</DIV></p><p>But it's a star with previously unidentified mass. </p> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>But it's a star with previously unidentified mass. <br /> Posted by dragon04</DIV></p><p>There's plenty of those.&nbsp; There's even more stars we can't even see.&nbsp; Galaxy masses aren't defined by the masses of the individual stars.&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[dragon04]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>There's plenty of those.&nbsp; There's even more stars we can't even see.&nbsp; Galaxy masses aren't defined by the masses of the individual stars.&nbsp; <br /> Posted by derekmcd</DIV></p><p>&nbsp;</p><p>But if galaxies are twice or thrice as massive as expansion models use as their baseline estimates, certainly you can see that it can make a significant difference.</p><p>Or are you saying that gravitational models are what determine the mass of galaxies? I would point out that based on those models, there are somewhat inexplicablethings that happem from the core of a galaxy to the outer edges of them in terms of orbital velocities. </p><p>Obviously, I'm a layman and you are a trained and credentialed expert based on the content of your postings, so I ask you to indulge me and tell me how and why I am wrong. </p> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[derekmcd]

<p><strong>But if galaxies are twice or thrice as massive as expansion models use as their baseline estimates, certainly you can see that it can make a significant difference.</strong></p><p>If galaxies were discovered to be 2 or 3 time more massive on average, there would be obvious issues with the tools used to determine galactic masses.&nbsp; There would be some fundamental flaws that might require a rethinking of the entire model.&nbsp; If the universe contained a significant amount more mass than what is currenty though, this might bring about a different conclusion as to the fate of the universe.</p><p>But in reality, other than some minor adjustments here and there, galactic masses are measured with a fair amount of accuracy. </p><p><strong>Or are you saying that gravitational models are what determine the mass of galaxies? I would point out that based on those models, there are somewhat inexplicablethings that happem from the core of a galaxy to the outer edges of them in terms of orbital velocities.</strong></p><p>There's a few different processes.&nbsp; Rotational velocity is pretty accurate.&nbsp; We can't sit there and measure the speed directly, but by using redshift, velocities can be determined.&nbsp; A spiral galaxy, for example, when viewed from the side... one side of the galaxy would be rotating away causing a redshift while the other side, the stars would be approaching you causing a blueshift.&nbsp; Depending on the amounts of the shifts, a velocity can be determined.&nbsp; With the velocity, mass can be determine much in the way we can determine the mass of the planets based on their orbital velocities and distance from the center.</p><p>The faster the velocity (depending on distance) the more mass required to keep it stable.&nbsp; The outer edges of galaxies are rotating at such speeds, they shoud be flying apart... but they don't.&nbsp; Enter dark matter.</p><p>Dark matter makes up a signficant portion of galactic mass.&nbsp; I don't have an exact number, but it's around 90% IIRC.&nbsp; The remaining 10% is mostly stars.&nbsp; Gas and dust is probably less than 1%. (For baryonic matter alone, 96% is stars while 4% is dust and gas).</p><p>Another accurate way is through gravitational lensing.&nbsp; Light originating from behind a galaxy is bent as it passes by in such a way that the mass can be determined.&nbsp; General Relativity taught us this little trick.</p><p>Luminosity of a galaxy can also determine it's mass, but I don't think this is quite as accurate due to both interstellar and intergalactic dust.&nbsp; Mostly interstellar dust around the cores of galaxies.</p><p>As you can see, the mass of individual stars isn't of much use except for maybe trying to determine the number of stars in a galaxy based on luminosity.&nbsp; I think there, they would have to assume the average mass of the stars in the galaxy depending on the age of the galaxy.&nbsp;</p><p><strong>Obviously, I'm a layman and you are a trained and credentialed expert based on the content of your postings, so I ask you to indulge me and tell me how and why I am wrong.</strong> </p>I'm not, but I appreciate the flattery <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" /><br /> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>