Search Publications
HD 144941: the most extreme helium-strong star
Fossati, L.; Przybilla, N.; Jeffery, C. S.
Since its discovery about 50 yr ago, HD 144941 has generally been classified as a peculiar member of the extreme helium (EHe) supergiant stars, a very rare class of low-mass hydrogen-deficient stars. We report the detection of a strong longitudinal magnetic field based on spectropolarimetry with FORS2 on the ESO VLT with surface-averaged longitudi…
Distribution of ionized, atomic, and PDR gas around S 1 in ρ Ophiuchus
Güsten, R.; Riquelme, D.; Mookerjea, B. +5 more
The early B star S 1 in the ρ Ophiuchus cloud excites an H II region and illuminates a large egg-shaped photon-dominated (PDR) cavity. The PDR is restricted to the west and southwest by the dense molecular ρ Oph A ridge, expanding more freely into the diffuse low-density cloud to the northeast. We analyzed new SOFIA GREAT, GMRT, and APEX data toge…
Constraining the Origin of the Puzzling Source HESS J1640-465 and the PeVatron Candidate HESS J1641-463 Using Fermi-Large Area Telescope Observations
Grondin, M. -H.; Lemoine-Goumard, M.; Clark, C. J. +6 more
There are only a few very-high-energy sources in our Galaxy that might accelerate particles up to the knee of the cosmic-ray spectrum. To understand the mechanisms of particle acceleration in these PeVatron candidates, Fermi-Large Area Telescope (LAT) and High-Energy Stereoscopic System (H.E.S.S.) observations are essential to characterize their γ…
An unbiased NOEMA 2.6 to 4 mm survey of the GG Tau ring: First detection of CCS in a protoplanetary disk
Chapillon, E.; Coutens, A.; Beck, T. L. +13 more
Context. Molecular line surveys are among the main tools to probe the structure and physical conditions in protoplanetary disks (PPDs), the birthplace of planets. The large radial and vertical temperature as well as density gradients in these PPDs lead to a complex chemical composition, making chemistry an important step to understand the variety …
High-contrast observations of brown dwarf companion HR 2562 B with the vector Apodizing Phase Plate coronagraph
Kenworthy, Matthew A.; Charbonneau, David; Close, Laird M. +8 more
The vector Apodizing Phase Plate (vAPP) is a class of pupil plane coronagraph that enables high-contrast imaging by modifying the Point Spread Function (PSF) to create a dark hole of deep flux suppression adjacent to the PSF core. Here, we recover the known brown dwarf HR 2562 B using a vAPP coronagraph, in conjunction with the Magellan Adaptive O…
A detailed study of X-ray cavities in the intracluster environment of the cool core cluster Abell 3017
Raychaudhury, Somak; Pandge, M. B.; Sebastian, Biny +1 more
We present a detailed analysis of a cool-core galaxy cluster Abell 3017, at a redshift of z = 0.219, which has been identified to be merging with its companion cluster Abell 3016. This study has made use of X-ray (Chandra), ultraviolet (UV) [Galaxy Evolution Explorer(GALEX)], optical [European Southern Observatory (ESO)/very large telescope (VLT)]…
Charge-exchange soft X-ray emission of highly charged ions with inclusion of multiple-electron capture
Cui, W.; Zhao, G.; Wu, Y. +7 more
Charge exchange has been recognized as a primary source of soft X-ray emission in many astrophysical outflow environments, including cometary and planetary exospheres impacted by the solar wind. Some models have been set up by using different data collections of charge-exchange cross-sections. However, multiple-electron transfer has not been inclu…
High-resolution X-ray spectroscopy of supergiant HMXB 4U 1700-37 during the compact object eclipse
Grinberg, V.; Hainich, R.; Torrejón, J. M. +6 more
We present an analysis of the first observation of the iconic high-mass X-ray binary 4U 1700-37 with the Chandra High-Energy Transmission Gratings (HETGs) during an X-ray eclipse. The goal of the observation was to study the structure/physical conditions in the clumpy stellar wind through high-resolution spectroscopy. We find the following: (a) Em…
The SOPHIE search for northern extrasolar planets. XVIII. Six new cold Jupiters, including one of the most eccentric exoplanet orbits
Bouchy, F.; Deleuil, M.; Moutou, C. +28 more
Context. Due to their low transit probability, the long-period planets are, as a population, only partially probed by transit surveys. Radial velocity surveys thus have a key role to play, in particular for giant planets. Cold Jupiters induce a typical radial velocity semi-amplitude of 10 m s−1, which is well within the reach of multipl…
The link between gas and stars in the S254-S258 star-forming region
Juvela, M.; Kirsanova, M. S.; Sobolev, A. M. +5 more
The paper aims to study relation between the distributions of the young stellar objects (YSOs) of different ages and the gas-dust constituents of the S254-S258 star formation complex. This is necessary to study the time evolution of the YSO distribution with respect to the gas and dust compounds that are responsible for the birth of the young star…