Related papers: A Search for Optical Laser Emission from Alpha Cen…
We use more than a decade of radial velocity measurements for $\alpha$ Cen A, B, and Proxima Centauri from HARPS, CHIRON, and UVES to identify the $M \sin i$ and orbital periods of planets that could have been detected if they existed. At…
Fluorescent Dark Matter has been suggested as a possible explanation of both the 3.5 keV excess in the diffuse emission of the Perseus Cluster and of the deficit at the same energy in the central active galaxy within that cluster, NGC 1275.…
We investigate the production of axion-like particles (ALPs) in stellar cores, where they interact with electromagnetic fields and electrons, with typical masses between $\mathcal O(0.1)$ and $\mathcal O(10)$ keV. These low-energy ALPs are…
Stars provide an enormous gain for interstellar communications at their gravitational focus, perhaps as part of an interstellar network. If the Sun is part of such a network, there should be probes at the gravitational foci of nearby stars.…
The ultra--high energy cosmic rays recently detected by several air shower experiments could have an extragalactic origin. In this case, the nearest active galaxy Centaurus A might be the source of the most energetic particles ever detected…
We present numerical simulations for energy spectra and angular distributions of nucleons above 10^{19} eV injected by the radio-galaxy Centaurus A at a distance 3.4 Mpc and propagating in extra-galactic magnetic fields in the sub-micro…
The photospheric radius is one of the fundamental parameters governing the radiative equilibrium of a star. We report new observations of the nearest solar-type stars Alpha Centauri A (G2V) and B (K1V) with the VLTI/PIONIER optical…
We have searched for TeV gamma-rays from Centaurus A and surrounding region out to +/- 1.0 deg using the CANGAROO 3.8m telescope. No evidence for TeV gamma-ray emission was observed from the search region, which includes a number of…
We present gamma-ray observations with the LAT on board the Fermi Gamma-Ray Telescope of the nearby radio galaxy Centaurus~A. The previous EGRET detection is confirmed, and the localization is improved using data from the first 10 months of…
$\alpha$ Centauri A is the closest solar-type star to the Sun and offers the best opportunity to find and ultimately to characterize an Earth-sized planet located in its Habitable Zone (HZ). Here we describe initial results from an ALMA…
The sodium laser guide star adaptive optics system ALFA, which is installed at the Calar Alto 3.5-m telescope, has been undergoing an intensive optimisation phase. Observations using natural guide stars that are presented in this paper,…
The Alpha Centauri system is the primary target for planet search as it is the closest star system composed of a solar twin Alpha Centauri A, a K-dwarf Alpha Centauri B and an M-dwarf Proxima Centauri, which has a confirmed planet in the…
Natural laser emission may be produced whenever suitable atomic energy levels become overpopulated. Strong evidence for laser emission exists in astronomical sources such as Eta Carinae, and other luminous stars. However, the evidence is…
We compare the first direct angular diameter measurements obtained on our closest stellar neighbour, Alpha Centauri, to recent model diameters constrained by asteroseismic observations. Using the VINCI instrument installed at ESO's VLT…
Centaurus A, at a distance of less than 4 Mpc, is the nearest radio-loud AGN. Its emission is detected from radio to very-high energy gamma-rays. Despite the fact that Cen A is one of the best studied extragalactic objects the origin of its…
The Pierre Auger Observatory has associated a few ultra high energy cosmic rays with the direction of Centaurus A. This source has been deeply studied in radio, infrared, X-ray and $\gamma$-rays (MeV-TeV) because it is the nearest…
At a distance of about 4.22 lightyears, it would take about 100,000 years for humans to visit our closest stellar neighbor Proxima Centauri using modern chemical thrusters. New technologies are now being developed that involve high-power…
We have observed the giant radio galaxy Centaurus A and the globular cluster $\omega$ Centauri in the TeV energy region using the CANGAROO-III stereoscopic system. The system has been in operation since 2004 withan array of four Imaging…
We present results of a search for optical counterparts of X-ray sources in and toward the globular cluster Omega Centauri (NGC 5139) using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. The ACS data consist of a…
Centaurus B (Cen B) is one of the closest and brightest radio-loud galaxy in the southern sky. This radio galaxy, proposed as a plausible candidate for accelerating ultra-high-energy cosmic rays (UHECRs), is near the highest-energy neutrino…