Related papers: Anomalous Variability of Dyson Megastructures
Ultracompact objects with light-rings (LRs) but without an event horizon could mimic black holes (BHs) in their strong gravity phenomenology. But are such objects dynamically viable? Stationary and axisymmetric ultracompact objects that can…
A survey for line profile variability in early A-type stars has been performed in order to detect nonradial pulsation signatures. The star HR 6139, with spectral type A2V and estimated T_eff=8800 K, shows evident line profile variations…
If current ideas about unified field theories are correct, macroscopic cosmic defects may well exist. The observation of such an entity would have enormous significance for our understanding of fundamental physics. This paper points out a…
The characteristic physical timescales near stellar-mass compact objects are measured in milliseconds. These timescales -- the free-fall time, the fastest stable orbital period, and stellar spin periods -- encode the fundamental physical…
There have been several recent suggestions that the Milky Way has rotating bar-like features based on HI and star count data. In this paper, I show that such features cause distinctive stellar kinematic signatures near OLR and ILR. The…
Rapidly rotating Myers-Perry black holes in d>5 dimensions were conjectured to be unstable by Emparan and Myers. In a previous publication, we found numerically the onset of the axisymmetric ultraspinning instability in the singly-spinning…
Asteroseismology is a powerful tool to access the internal structure of stars. Apart from the important impact of theoretical developments, progress in this field has been commonly associated with the analysis of time-resolved observations.…
Recent observations show that rings and gaps are ubiquitous in protoplanetary discs. These features are often interpreted as being due to the presence of planets; however, the effect of planetary migration on the observed morphology has not…
Real scalar fields, e.g. the axion, cannot condensate into stationary solitonic configurations to form star-like structures, eventually either dispersing or collapsing. However, by relaxing the stationarity condition on the metric, it has…
Light curves of young stars exhibit photometric variability over hours to decades and across a wide range of amplitudes. On time scales beyond a few rotation periods, these light curves are typically stochastic. The variability arises from…
Binarity is often invoked to explain peculiarities that can not be explained by the standard theory of stellar evolution. Detecting orbital motion via the Doppler effect is the best method to test binarity when direct imaging is not…
We consider global catastrophic risks due to cosmic explosions (supernovae, magnetars and gamma-ray bursts) and possible mitigation strategies by humans and other hypothetical intelligent beings. While by their very nature these events are…
For 30 years, cyclical wind variability in OB stars has puzzled the astronomical community. Phenomenological models involving co-rotating bright spots provide a potential explanation for the observed variations, but the underlying physics…
Precision timing of highly stable milli-second pulsars is a promising technique for the detection of very low frequency sources of gravitational waves. In any single pulsar, a stochastic gravitational wave signal appears as an additional…
Several interstellar environments produce 'anomalous microwave emission', with brightness-peaks at tens-of-gigahertz frequencies. The emission's origins are uncertain - rapidly-spinning nano-particles could emit electric-dipole radiation,…
Protoplanetary disks with large inner dust cavities are thought to host massive planetary or substellar companions. These disks show asymmetries and rings in the millimeter continuum, caused by dust trapping in pressure bumps, and…
Unsupervised machine learning methods are used to identify structural changes using the melting point transition in classical molecular dynamics simulations as an example application of the approach. Dimensionality reduction and clustering…
We carry out three dimensional SPH simulations to show that a migrating giant planet strongly suppresses the spiral structure in self-gravitating discs. We present mock ALMA continuum observations which show that in the absence of a planet,…
A striking coincidence of revolution periods of S-stars orbiting a supermassive black hole at the Galactic Center of the Milky Way and oscillation periods of such solar and terrestrial observables as the sunspot number, the geomagnetic…
Protoplanetary disks around young stars harbor many structures related to planetary formation. Of particular interest, spiral patterns were discovered among several of these disks and are expected to be the sign of gravitational…