The discovery of metal-rich planetary nebulae in the outer regions of the Andromeda Galaxy, using data from the GTC, gives evidence of a possible encounter between galaxies

Imágenes y vídeo del cometa Lovejoy tomados desde el Observatorio del Teide, en Tenerife (Islas Canarias), y sus inmediaciones

Its latest data release contains information about 470 million stars and galaxies

We obtained GALEX FUV, NUV, and Spitzer/IRAC 3.6 µm photometry for >2000 galaxies, available for 90% of the S4G sample. We find a very tight "GALEX Blue Sequence (GBS)" in the (FUV − NUV) versus (NUV − [3.6]) color-color diagram which is populated by irregular and spiral galaxies, and is mainly driven by changes in the formation timescale (τ ) and a degeneracy between τ and dust reddening. The tightness of the GBS provides an unprecedented way of identifying starforming galaxies and objects that are just evolving to (or from) what we call the "GALEX Green Valley (GGV)". At the red end of the

We provide a complete characterization of the astrophysical properties of the σ Ori Aa, Ab, B hierarchical triple system and an improved set of orbital parameters for the highly eccentric σ Ori Aa, Ab spectroscopic binary. We compiled a spectroscopic data set comprising 90 high-resolution spectra covering a total time span of 1963 days. We applied the Lehman-Filhés method for a detailed orbital analysis of the radial velocity curves and performed a combined quantitative spectroscopic analysis of the σ Ori Aa, Ab, B system by means of the stellar atmosphere code FASTWIND. We used our own plus

The two pyramids built during the Old Kingdom by the Fourth Dynasty King Sneferu at Dahshur are usually considered as two consecutive projects, the second – that of the Red Pyramid – being generated by a presumably failure of the first, the Bent Pyramid. In the present paper, we show that the archaeological proofs of such a scenario are far from obvious and that, on the contrary, a series of architectural, topographical, epigraphic, and astronomical hints point to a unitary project probably conceived from the very beginning in terms of the two pyramids and their annexes. Altogether the two