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Fernando Peña
An article about the finding of "unexpected" solar-like oscillations (stochastically-driven) in a Delta Scuti star. The first author gave a nice talk in the Spain conference about this results (and she asked me to say "hello" to Michael Gruberbauer). http://www.nature.com/nature/journal/vaop/ncurrent/full/nature10389.html
Fernando Peña
Fernando Peña added a document to this group
Fernando Peña
Fernando Peña In theory Kepler and CoRoT may also be useful to detect low-mass objects (down to Jupiters) from the harmonical non-transiting light variations happening on the primary.
16th June
Fernando Peña
Fernando Peña added a document to this group
Fernando Peña
Fernando Peña A recent review of some of the findings of CoRoT and Kepler and the science behind it.
28th April
Daniel Majaess
Daniel Majaess Thanks for that article. R. Gilliband provided a talk summarizing the latest Kepler/asteroseismology results at the AAS meeting, but it's nice to have a document in hand.
2nd June
Fernando Peña
Fernando Peña added a document to this group
Fernando Peña
Fernando Peña This one addresses part of the paper by Litlefair etal. entitled "Accretion-induced luminosity spreads blabla.....". It is a nice little introduction to inferring the age of pre-MS stars using the H-R diagram combined with evolutionary models, where the author also considers and explain the sources of uncertainty.
25th February
Daniel Majaess
Daniel Majaess Joel Tanner, a past student of David G., Ian, and Bob, wrote a nice thesis that discussed in part the age-spread phenonmenon in young (PMS) clusters. The paradox being that at the opposite end of the age spectrum, the coeval nature of stars in certain globular clusters is being contested (e.g., Omega Cen). I also wonder what is the impact of prop...
29th March
Fernando Peña
Fernando Peña added a document to this group
Fernando Peña
Fernando Peña added a document to this group
Fernando Peña
Fernando Peña Color-magnitude diagrams (CMDs) for observed young star forming clusters are presented. In the current theory, the youngest stars are the brightest and undergo accretion. The resulting star-disk interaction (lock-on) would slow down the star. However these CMDs show that the brightest stars are also the ones rotating faster. The authors then go to ...
22nd February
Fernando Peña
Fernando Peña added a document to this group
Fernando Peña
Fernando Peña More about Cepheid mass discrepancy:

This is a very accurate Cepheid dynamical mass estimation, where the authors argue that, at least for this highly-precise measurement, there is NO MASS DISCREPANCY between the "pulsation" and the "evolutionary" mass.
4th January
Michael Gruberbauer
Michael Gruberbauer This is great! It still seems a little bit fishy to me, because basically the team HAS to reproduce the dynamical mass and the radius. That you can do that by adjusting the parameters (metallicity, core overshoot) available in your model is no surprise. But they give a reasonable justification for their parameters - and they don't seem to differ at...
6th January
Fernando Peña
Fernando Peña added a document to this group
Fernando Peña
Fernando Peña added a document to this group
Fernando Peña
Fernando Peña This 2M_Sun A5 star is rotating (P_rot=14.5 hrs) at almost 90% of its critical frequency.

What is striking is that they have identified a dozen of rotationally modified g-modes (periods of 1-10 days), which seem to be evenly separated (frequency difference proportional to the azimuthal quantum number 'm') in frequency space (something unexpected ...
7th December
Fernando Peña
Fernando Peña added documents to this group
Fernando Peña
Fernando Peña Technology is allowing us now (mostly driven by planet finders) to measure the inclination of the spin axis of binaries with respect to their orbits. The Banana project (specially design to measure the inclination angle) has discovered that, surprisingly, there are young and detached stellar binaries that have either very misaligned spin axes or ve...
30th November
David Guenther
David Guenther Sorry if this duplicates what has already been talked about at the meeting yesterday (which I could not attend).

OK, so what is this mass discrepancy in cepheids all about, as mentioned during journal club and now here? At JC I could not understand how pulsation mass and stellar evolution mass would be different. The above paper does not go into t...
4th December
Fernando Peña
Fernando Peña Hi David.

You didn't miss anything cause we (I in particular) were so interested in the "progress reports" that I forgot to leave some time for discussing the papers.

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As for the mass discrepancy. Yes I agree about the problem with the stellar models. The paper I posted mentioned that usually stellar evolution "overestimates" the mass,...
6th December
Fernando Peña
Fernando Peña added a document to this group
Fernando Peña
Fernando Peña added a document to this group
Fernando Peña
Fernando Peña Is the universality implied from the similarities of the individual mode frequencies per mode per star? (more or less they all lie on top of each other in plots 2 and 3)
12th November
Michael Gruberbauer
Michael Gruberbauer It is simply a "flashy" way to say: "We observe that the asymptotic theory is valid. It holds throughout the red giant branch. Only the frequency spacings (and offsets) governing the asymptotic relation change with the stellar fundamental parameters. Hence, with some scaling and shifting, every red giant looks more or less the same."
18th November
Fernando Peña
I'm learning how to use this.....
Fernando Peña
Fernando Peña added a document to this group
Fernando Peña likes this.
Fernando Peña
Fernando Peña An example of how we can share interesting papers, and let others to see what we are reading.

Simply go to the journal you are reading (e.g., astroph), and when you find an interesting paper (click on the abstract) you wish to share press the "mendeley" red icon at the right of the abstract, and then select where do you want to share it (your own ...
7th November
Fernando Peña
Created by Fernando Peña

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Group devoted to discuss all kind of stuff that involve stars. We meet approximately once a month, every first Friday of the month at 10 AM.

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