Related papers: Improved distances to several Galactic OB associat…

The Sun is located inside an extremely low density region of quite irregular shape called the Local Bubble. Close to the Local Bubble, there is an even larger cavity known as Loop I. A ring-like feature observed in X-ray and HI has been…

We analyse a sample of over 1000 stars from 32 fields imaged in the V and I bands with the Wide Field and Planetary Camera, on board of the Hubble Space Telescope. The fields are located at Galactic latitudes | b | >= 15deg and in various…

We present high-resolution optical spectra (at ~0.6--1.8 km s-1) of interstellar CN, CH, CH^+, \ion{Ca}{1}, \ion{K}{1}, and \ion{Ca}{2} absorption toward 29 lines of sight in three star-forming regions, \rho Oph, Cep OB2, and Cep OB3. The…

We report new HST COS and STIS spectroscopy of a star-forming region (~100 solar masses/year) in the center of the X-ray cluster RXJ1532.9+3021 (z=0.362), to follow-up the CLASH team discovery of luminous UV filaments and knots in the…

New observations from the Gaia spacecraft have traced an emerging demographic of low-mass associations disconnected from larger associations or GMCs. The first of these associations were recently characterized, but the star-forming…

Spatially extended Ly$\alpha$ nebulae, known as Ly$\alpha$ blobs (LABs), are a rare population at $z > 2$ that are thought to trace proto-groups or the progenitors of massive galaxies in the present-day universe. However, their dark matter…

In order to reveal the stellar mass distribution of z~3 galaxies, we are conducting deep imaging observations of U-dropout Lyman Break Galaxies (LBGs) with Adaptive Optics (AO) systems in K-band, which corresponds to rest-frame V-band of…

Statistics of low-mass pre-main sequence binaries in the Orion OB1 association with separations ranging from 0.6" to 20" (220 to 7400 au at 370 pc) are studied using images from the VISTA Orion mini-survey and astrometry from Gaia. The…

A comprehensive census of the stellar content of the nearby OB associations is presented, based on Hipparcos positions, proper motions, and parallaxes. Moving groups are identified by combining de Bruijne's refurbished convergent point…

We present HST images of star-forming galaxies at redshifts z>3. These galaxies have been color selected for having a Lyman discontinuity in the otherwise flat (in f_\nu units) UV spectra of unreddened star formation. The spectroscopic…

The Galactic Center (GC) is surrounded by plasma lobes that extend up to ~14 kpc above and below the plane. Until now, UV absorption studies of these lobes have only focused on high-velocity components (|v_LSR| > 100 km/s) because low- and…

We present NOT optical observations of a clump (l = 127.9435 deg, b = +1.8298 deg), embedded in an extended, irregularly shaped, diffuse optical nebula. This condensation shows an emission-line spectrum typical of classic HII regions.…

Near-infrared observations of line emission from excited H2 and in the continuum are reported in the direction of the Orion molecular cloud OMC1, using the European Southern Observatory Very Large Telescope UT4, equipped with the NAOS…

We resolve the kinematic distance ambiguity for 266 inner Galaxy HII regions out of a sample of 291 using existing HI and 13CO sky surveys. Our sample contains all HII regions with measured radio recombination line (RRL) emission over the…

In this review I discuss different theories of the formation of OB associations in the Milky Way, and provide the observational evidences in support of them. In fact, the second release of Gaia astrometric data (April 2018) is…

The single region of ongoing star formation in the galaxy IC 1613 has been observed in order to reveal the nature of compact emission-line objects at the edges of two shells in the complex, identified earlier in H-alpha line images. The…

We report the large scale structure and clustering analysis of Ly$\alpha$ emitters (LAEs) and Ly$\alpha$ blobs (LABs) at $z=2.2-2.3$. Using 3,341 LAEs, 117 LABs, and 58 bright (Ly$\alpha$ luminosity $L_{\rm Ly\alpha}>10^{43.4}$ erg…

Most massive stars belong to multiple systems, yet the formation process leading to such high multiplicity remains insufficiently understood. To help constrain the different formation scenarios that exist, insights on the low-mass end of…

We report new, $\sim$1000 AU spatial resolution observations of 225 GHz dust continuum emission towards the OB cluster-forming molecular clump G33.92+0.11. On parsec scales, this molecular clump presents a morphology with several arm-like…

We consider two previously studied samples of OB stars with different distance scales. The first one consists of 98 massive spectroscopic binary stars with photometric distances, and the second one consists on 140 OB stars with the…