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Distances to Galactic OB Stars: Photometry versus Parallax
Shull, J. Michael; Danforth, Charles W.
For application to surveys of interstellar matter and Galactic structure, we compute new spectrophotometric distances to 139 OB stars frequently used as background targets for UV spectroscopy. Many of these stars have updated spectral types and digital photometry with reddening corrections from the Galactic O-Star (GOS) spectroscopic survey. We co…
On the size of the CO-depletion radius in the IRDC G351.77-0.51
Menten, K. M.; Schisano, E.; Leurini, S. +5 more
An estimate of the degree of CO-depletion (fD) provides information on the physical conditions occurring in the innermost and densest regions of molecular clouds. A key parameter in these studies is the size of the depletion radius, i.e. the radius within which the C-bearing species, and in particular CO, are largely frozen on to dust g…
Exploring the R CrA environment with SPHERE. Discovery of a new stellar companion
Lodato, G.; Barbieri, M.; Henning, T. +39 more
Aims: R Coronae Australis (R CrA) is the brightest star of the Coronet nebula of the Corona Australis (CrA) star forming region. This star is very red in color, probably due to dust absorption, and is strongly variable. High-contrast instruments allow for an unprecedented direct exploration of the immediate circumstellar environment of this s…
On the Origin of Solar Torsional Oscillations and Extended Solar Cycle
Kosovichev, A. G.; Pipin, V. V.
We present a nonlinear mean-field model of the solar interior dynamics and dynamo, which reproduces the observed cyclic variations of the global magnetic field of the Sun, as well as the differential rotation and meridional circulation. Using this model, we explain, for the first time, the extended 22 yr pattern of the solar torsional oscillations…
Which Photospheric Characteristics Are Most Relevant to Active-Region Coronal Mass Ejections?
Guerra, Jordan A.; Park, Sung-Hong; Bloomfield, D. Shaun +2 more
We investigate the relation between characteristics of coronal mass ejections and parameterizations of the eruptive capability of solar active regions widely used in solar flare-prediction schemes. These parameters, some of which are explored for the first time, are properties related to topological features, namely, magnetic polarity-inversion li…
New Test of Lorentz Invariance Using the MICROSCOPE Space Mission
Métris, Gilles; Rodrigues, Manuel; Touboul, Pierre +11 more
We use data from the T-SAGE instrument on board the MICROSCOPE space mission to search for Lorentz violation in matter-gravity couplings as described by the Lorentz violating standard model extension (SME) coefficients (a¯ eff)µw , where (µ =T , X , Y , Z ) and (w =e , p , n ) for the electron, proton, …
Detecting Thin Stellar Streams in External Galaxies: Resolved Stars and Integrated Light
Williams, Benjamin F.; Ibata, Rodrigo A.; Johnston, Kathryn V. +3 more
The morphology of thin stellar streams can be used to test the nature of dark matter. It is therefore crucial to extend searches for globular cluster (GC) streams to other galaxies than the Milky Way. In this paper, we investigate the current and future prospects of detecting GC streams in external galaxies in resolved stars (e.g., with Wide Field…
The dynamical matter density in the solar neighbourhood inferred from Gaia DR1
Widmark, Axel; Monari, Giacomo
We determine the total dynamical density in the solar neighbourhood using the Tycho-Gaia Astrometric Solution catalogue. Astrometric measurements of proper motion and parallax of stars inform us of both the stellar number density distribution and the velocity distribution of stars close to the plane. Assuming equilibrium, these distributions are i…
A stellar census in globular clusters with MUSE: multiple populations chemistry in NGC 2808
Dreizler, S.; Bastian, N.; Latour, M. +8 more
Context. Galactic globular clusters (GCs) are now known to host multiple populations displaying particular abundance variations. The different populations within a GC can be well distinguished following their position in the pseudo two-colors diagrams, also referred to as "chromosome maps". These maps are constructed using optical and near-UV phot…
Stellar Mass Growth of Brightest Cluster Galaxy Progenitors in COSMOS Since z ∼ 3
Casey, Caitlin M.; Kartaltepe, Jeyhan S.; Le Fèvre, Olivier +5 more
We examine the role of environment on the in situ star formation (SF) hosted by the progenitors of the most massive galaxies in the present-day universe, the brightest cluster galaxies (BCGs), from z ∼ 3 to present in the COSMOS field. Progenitors are selected from the COSMOS field using a stellar mass cut motivated by the evolving cumulative como…