<meta http-equiv="Content-Type" content="text/html; charset=utf-8"><p dir="ltr">I created that dataset, and yes, the stars have ages that are in the future (gasoline uses stellar ages to determine feedback rates, so stars with ages in the future will not do any feedback, which I needed for the experiment that dataset came from). Sorry for the confusion.</p>
<div class="gmail_quote">On Mar 30, 2015 2:33 PM, "Desika Narayanan" <<a href="mailto:dnarayan@haverford.edu">dnarayan@haverford.edu</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hey Nathan,<div><br></div><div>This is great - thanks!</div><div><br></div><div>-d</div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Mar 30, 2015 at 2:24 PM, Nathan Goldbaum <span dir="ltr"><<a href="mailto:nathan12343@gmail.com" target="_blank">nathan12343@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_extra"><br><div class="gmail_quote"><div><div>On Mon, Mar 30, 2015 at 11:10 AM, Desika Narayanan <span dir="ltr"><<a href="mailto:dnarayan@haverford.edu" target="_blank">dnarayan@haverford.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div dir="ltr">Hi All,<br><div><br></div><div>I'm trying to understand some of the stellar ages that the Tipsy example data (the isolated galaxy) at:</div><div><br></div><div><a href="http://yt-project.org/data/" target="_blank">http://yt-project.org/data/</a></div><div><br></div><div>When I examine the formation time with the super-simple script:</div><div>
<p><a href="http://paste.yt-project.org/show/5501/" target="_blank">http://paste.yt-project.org/show/5501/</a></p><p>I get: </p><p>
</p><p>max star age: 100.000499852 Gyr</p><p>I thought normally the formation time was the current simulation time minus the stellar age for Tipsy outputs - am I interpreting this wrongly?</p><p><br></p></div></div></blockquote><div><br></div></div></div><div>Hi Desika,</div><div><br></div><div>I encountered this before. Take a look at the following section of the docs, which makes use of this dataset:</div><div><br></div><div><a href="http://yt-project.org/docs/dev/analyzing/filtering.html#filtering-particle-fields" target="_blank">http://yt-project.org/docs/dev/analyzing/filtering.html#filtering-particle-fields</a><br></div><div><br></div><div>I don't have a copy of gasoline to confirm this, but the conclusion I came to is that the stars in the initial conditions for this simulation were given a creation time arbitrarily far in the future, generating spurious stellar ages.</div><div><br></div><div>If you instead define particle filters for formed stars like so:</div><div><br></div><div><div>def young_stars(pfilter, data):</div><div> age = data.ds.current_time - data[pfilter.filtered_type, "creation_time"]</div><div> filter = np.logical_and(age.in_units('Myr') <= 5, age >= 0)</div><div> return filter</div><div><br></div><div>def old_stars(pfilter, data):</div><div> age = data.ds.current_time - data[pfilter.filtered_type, "creation_time"]</div><div> filter = np.logical_or(age.in_units('Myr') >= 5, age < 0)</div><div> return filter</div></div><div><br></div><div>where I've arbitrarily chosen 5 Myr as the cutoff for old stars and young stars, you'll find that your results make more sense.</div><div> </div><div>HTH,</div><div><br></div><div>Nathan</div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div dir="ltr"><div><p></p><p>Thanks,<br>desika</p><p><br></p><p><br></p></div></div>
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