Related papers: On a spectral pattern of the Von-Neumann probes
Recent analyses of nebular spectra have resulted in discrepant abundances from CNO forbidden and recombination lines. We consider independent methods of determining ion abundances for emission nebulae, comparing ion emission measures with…
I consider novel ways by which Gamma-Ray Bursts (GRBs) and quasars can be used to probe the universe. Clues about how and when was the intergalactic medium ionized can be read off the UV emission spectrum of GRB explosions from the first…
Detection of weak radial velocity shifts of host stars induced by orbiting planets is an important technique for discovering and characterizing planets beyond our solar system. Optical frequency combs enable calibration of stellar radial…
The investigation of extragalactic Supernova Remnants (SNRs) gives us the advantage of surmounting the challenges we are usually confronted with when observing Galactic SNRs, most notably Galactic extinction and distance uncertainties. At…
The majority of exoplanets found to date have been discovered via the transit method, and transmission spectroscopy represents the primary method of studying these distant worlds. Currently, in-depth atmospheric characterization of…
The direct observation of cold and temperate planets within 1 to 10 AU would be extremely valuable for uncovering their atmospheric compositions but remains a formidable challenge with current astronomical methods. Ground-based optical…
Context. Collecting a large variety of exoplanetary atmosphere measurements is crucial to improve our understanding of exoplanets. In this context, it is likely that the field would benefit from broad species surveys, particularly using…
Interplanetary solar radio type III bursts provide the means for remotely studying and tracking energetic electrons propagating in the interplanetary medium. Due to the lack of direct radio source imaging, several methods have been…
Supernovae of type IIn possess spectral signatures that indicate an intense interaction between the supernova ejecta and surrounding dense circumstellar material cast off by the star in pre-explosion mass-loss episodes. Studying this…
This review discussed near- and mid- infrared observations of ultracompact (UC) HII regions. The importance of ISO mid-IR fine-structure nebular lines is emphasised since only a small fraction of UCHII regions are observed directly in the…
We propose methods to perform intensity interferometry of photons having two different wavelengths. Distinguishable particles typically cannot interfere with each other, but we overcome that obstacle by processing the particles via…
Protostellar jets and outflows are pointers of star-formation and serve as important sources of momentum and energy transfer to the interstellar medium. Radio emission from ionized jets have been detected towards a number of protostellar…
We review some of the ways that X-ray observations provide unique information on radio galaxies. Thermal bremsstrahlung X-ray emission provides detailed data on ambient densities and temperatures. These parameters in turn can be used for…
Planets reflect and linearly polarize the radiation that they receive from their host stars. The emergent polarization is sensitive to aspects of the planet atmosphere such as the gas composition and the occurrence of condensates and their…
In this paper, we review the various ways in which an infrared stellar interferometer can be used to perform direct detection of extrasolar planetary systems. We first review the techniques based on classical stellar interferometry, where…
In addition to study extragalactic stellar populations in their integrated light, the detailed analysis of individual resolved objects has become feasible, mainly for luminous giant stars and for extragalactic planetary nebulae (XPNe) in…
Extreme Scattering Events and pulsar secondary spectra have highlighted fundamental problems in our understanding of the dynamics of interstellar turbulence. We describe some of these problems in detail and present the theory behind the…
Advanced civilizations capable of interstellar travel, if they exist, are likely to have advanced propulsion methods. Spaceships moving at high speeds would leave a particular signature which could be detected from Earth. We propose a…
Evidence derived with minimal assumptions from existing published observations is presented to show that an ion-proton plasma is the source of radio-frequency emission in millisecond and in normal isolated pulsars. There is no primary…
We present observations of H_2 fluorescence at wavelengths between 1000 and 1200 A from the bright reflection nebula IC 63. Observations were performed with the Berkeley spectrograph on the ORFEUS-SPAS II mission. To the best of our…