# Be stars - short variations

The origin of short-times variations in the brightness of Be stars is not clear. Some researchers consider them a consequence of non-radial pulsations. Some researchers consider them a consequence of a corotating structure in the gas above the photosphere of a star.

Which papers consider these options, please?

• I've added a link to "Be star; variability" for readers (like myself) who don't know what that is. If it's the wrong link, or there is something better, please feel free to edit or roll back. Thanks!
– uhoh
Jul 21 at 23:23

Learning how to tactfully and strategically read/skim/scan through many papers to find the bits of information or other papers that you're looking for (and leaving a more in-depth examination for later when you can invest the time, perhaps) is an essential ingredient in being able to answer one's own questions in research. Although I will not completely answer your question here, since I think no one should do it for you, I will point out two papers that helped me find the papers that (I think) you're looking for.

Review articles can be very helpful for sifting through a large amount of papers, but sometimes observational studies can also be helpful for grappling with the theoretical literature since the observers are often interested in trying to use data to select certain theoretical models over others, etc... Also, the nasa ads website is extremely helpful to these ends. Here is their manual for submitting search queries, but honestly, just simply googling things like "nasa ads Be star variability" would have likely gotten you to these papers, too.

The introduction of this population study of Be variability by Labadie-Bartz $$et~al.$$ is very nicely written, and in the abstract they state:

We analyze KELT light curves of 610 known Be stars in both the northern and southern hemispheres in an effort to study their variability. Consistent with other studies of Be star variability, we find most of the stars to be photometrically variable. We derive lower limits on the fraction of stars in our sample that exhibit features consistent with non-radial pulsations (25%), outbursts (36%), and long-term trends in the circumstellar disk (37%), and show how these are correlated with spectral sub-types. Other types of variability, such as those owing to binarity, are also explored. Simultaneous spectroscopy for some of these systems from the Be Star Spectra database allow us to better understand the physical causes for the observed variability, especially in cases of outbursts and changes in the disk.

And so, they then published another study that focused on gaseous structures, e.g. circumbinary disks and outbursts, around Be stars.

The systems studied here show variability including transitions from a diskless to a disk-possessing state (and vice versa), and persistent disks that vary in strength, being replenished at either regularly or irregularly occurring intervals. We detect disk-building events (outbursts) in the light curves of 28% of our sample. Outbursts are more commonly observed in early- (57%), compared to mid- (27%) and late-type (8%) systems........... The duration of disk buildup and dissipation phases are measured for 70 outbursts, and we find that the average outburst takes about twice as long to dissipate as it does to build up in optical photometry. Our analysis hints that dissipation of the inner disk occurs relatively slowly for late-type Be stars.

I hope these help! Feel free to explore and ask further questions here.

• Very nice explanation on how to go through literatature. Jul 22 at 23:03