Related papers: BRITEning up the Be Phenomenon
The BRITE Constellation of nanosatellites obtained mmag photometry of 28 Cygni for 11 months in 2014-2016. Observations with the Solar Mass Ejection Imager in 2003-2010 and 118 H$\alpha$ line profiles were added. For decades, 28 Cyg has…
New high-cadence observations with BRITE covering many months confirm that coupled pairs of nonradial pulsation modes are widespread among early-type Be stars. With the difference frequency between the parental variations they may form a…
A new investigation of the variability of the SPB-type star 53 Per is presented. The analysis of the BRITE photometry allowed us to determine eight independent frequencies and the combination one. Five of these frequencies and the…
Space photometry has revealed rich pulsation spectra in classical Be stars. Often frequency pairs can be found that differ by nearly the frequency of a third genuine stellar variability. The lowest currently known of these so-called…
We report on finding variations in amplitude of the two main oscillation frequencies found in the Be star Achernar, over a period of 5 years. They were uncovered by analysing photometric data of the star from the SMEI instrument. The two…
Classical Be stars, regardless of spectral subtype, display multiperiodic light modulations in the frequency range 0.1-12 d$^{-1}$, when observed with high-cadence and long duration. This behaviour is attributed to non-radial pulsations…
Be stars have generally been characterized by the emission lines in their spectra, and especially the time variability of those spectroscopic features. They are known to also exhibit photometric variability at multiple timescales, but have…
The Be star 102719279 is an interesting target observed with CoRoT during two runs, giving us the possibility to study the stability of the detected frequencies and to search for any correlation with outburts, as it was recently found in…
The majority of the well-studied Delta Scuti stars show frequency pairs in the power spectra with frequency separations less than 0.06 c/d(0.7 microHz) as well as amplitude variability. We examine the interpretation in terms of separate…
The light elements, Li, Be, and B, provide tracers for many aspects of astronomy including stellar structure, Galactic evolution, and cosmology. We have taken spectra of Be in 117 metal-poor stars ranging in metallicity from [Fe/H] = -0.5…
Context. Be stars are physically complex systems that continue to challenge theory to understand their rapid rotation, complex variability and decretion disks. $\gamma$ Cassiopeiae ($\gamma$ Cas) is one such star but is even more curious…
The nature of the observed amplitude variability of several modes in the Delta Scuti star FG Vir is examined. In this star, three frequencies show strong amplitude and phase variations. In the power spectrum, these frequencies also show up…
The abundance of beryllium in the oldest, most metal-poor stars acts as a probe of early star formation and Galactic chemical evolution. We have analyzed high-resolution, high signal-to-noise Keck/HIRES spectra of 24 stars with [Fe/H] from…
We present an investigation of a large sample of confirmed (N=233) and candidate (N=54) Galactic classical Be stars (mean V magnitude range of 6.4 to 12.6 mag), with the main aim of characterizing their photometric variability. Our sample…
Aims. We attempt to determine if a dependency on spectral subtype or vsini exists for stars undergoing phase-changes between B and Be states, as well as for those stars exhibiting variability in H{\alpha} emission. Methods. We analyse the…
There are many Slowly Pulsating B (SPB) stars and gamma Dor stars in the Kepler Mission data set. The light curves of these pulsating stars have been classified phenomenologically into stars with symmetric light curves and with asymmetric…
Beryllium is not destroyed as easily as Li, so the abundances of Li and Be together can tell us more about the internal physical processes in stars than either element can alone. We have obtained high-resolution (45,000) and high…
As early-type stars with a rotation speed close to their critical velocity, Be stars experience an event called the Be phenomenon. The material in their equator is ejected into outside space during the Be phenomenon and forms a…
We studied the variability of the magnetic O-type supergiant $\zeta$ Ori Aa using multi-colour BRITE photometry. We confirmed the known rotation frequency $f_{\rm rot} = 0.15 \pm 0.02$ c/d, and detected some of its higher harmonics, of…
Fast rotation seems to be the mayor factor to trigger the Be phenomenon. Surface fast rotation can be favored by initial formation conditions, such as abundance of metals. We have observed 118 Be stars up to the apparent magnitudes V=9 mag.…