Search Publications
An X-ray survey of the central molecular zone: Variability of the Fe Kα emission line
Ponti, G.; Morris, M. R.; Terrier, R. +4 more
There is now abundant evidence that the luminosity of the Galactic super-massive black hole (SMBH) has not always been as low as it is nowadays. The observation of varying non-thermal diffuse X-ray emission in molecular complexes in the central 300 pc has been interpreted as delayed reflection of a past illumination by bright outbursts of the SMBH…
Studying the Ultraviolet Spectrum of the First Spectroscopically Confirmed Supernova at Redshift Two
Benoit-Lévy, A.; Bechtol, K.; Zheng, W. +89 more
We present observations of DES16C2nm, the first spectroscopically confirmed hydrogen-free superluminous supernova (SLSN-I) at redshift z≈ 2. DES16C2nm was discovered by the Dark Energy Survey (DES) Supernova Program, with follow-up photometric data from the Hubble Space Telescope, Gemini, and the European Southern Observatory Very Large Telescope …
Long-term solar activity studies using microwave imaging observations and prediction for cycle 25
Gopalswamy, N.; Yashiro, S.; Mäkelä, P. +1 more
We use microwave imaging observations from the Nobeyama Radioheliograph at 17 GHz for long-term studies of solar activity. In particular, we use the polar and low-latitude brightness temperatures as proxies to the polar and active-region magnetic fields, respectively. We also use the locations of prominence eruptions as a proxy to the filament loc…
More Rapidly Rotating PMS M Dwarfs with Light Curves Suggestive of Orbiting Clouds of Material
Cody, Ann Marie; Rebull, Luisa; Hillenbrand, Lynne A. +8 more
In a previous paper, using data from K2 Campaign 2, we identified 11 very low mass members of the ρ Oph and Upper Scorpius star-forming region as having periodic photometric variability and phased light curves showing multiple scallops or undulations. All of the stars with the “scallop-shell” light curve morphology are mid-to-late M dwarfs without…
Reanalysis of nearby open clusters using Gaia DR1/TGAS and HSOY
Reffert, Sabine; Piskunov, Anatoly E.; Kharchenko, Nina V. +3 more
Context. Open clusters have long been used to gain insights into the structure, composition, and evolution of the Galaxy. With the large amount of stellar data available for many clusters in the Gaia era, new techniques must be developed for analyzing open clusters, as visual inspection of cluster color-magnitude diagrams is no longer feasible. An…
Cloud Atlas: Discovery of Rotational Spectral Modulations in a Low-mass, L-type Brown Dwarf Companion to a Star
Schneider, Glenn; Apai, Dániel; Burgasser, Adam J. +11 more
Observations of rotational modulations of brown dwarfs and giant exoplanets allow the characterization of condensate cloud properties. As of now, rotational spectral modulations have only been seen in three L-type brown dwarfs. We report here the discovery of rotational spectral modulations in LP261-75B, an L6-type intermediate surface gravity com…
A Significant Overluminosity in the Transiting Brown Dwarf CWW 89Ab
Burrows, Adam; Davenport, James R. A.; Montet, Benjamin T. +3 more
We observed eclipses of the transiting brown dwarf CWW 89Ab at 3.6 and 4.5 µm using Spitzer/IRAC. The CWW 89 binary system is a member of the 3.0 ± 0.25 Gyr old open cluster Ruprecht 147 and is composed of a Sun-like primary and an early M-dwarf secondary separated by a projected distance of 25 au. CWW 89Ab has a radius of 0.937 ± 0.042 {R}<…
First direct detection of a polarized companion outside a resolved circumbinary disk around CS Chamaeleonis
Ménard, F.; Schmidt, T. O. B.; Ginski, C. +18 more
Aims: To understand planet formation it is necessary to study the birth environment of planetary systems. Resolved imaging of young planet forming disks allows us to study this environment in great detail and find signs of planet-disk interaction and disk evolution. In the present study we aim to investigate the circumstellar environment of t…
Optical Counterparts of Ultraluminous X-Ray Sources NGC 4559 X-10 and NGC 4395 ULX-1
Vinokurov, A.; Atapin, K.; Fabrika, S.
We study the optical counterparts of ultraluminous X-ray sources (ULXs) NGC 4559 X-10 and NGC 4395 ULX-1. Their absolute magnitudes, after taking reddening into account, are M V ≈ -5.3 and M V ≈ -6.2, respectively. The spectral energy distribution (SED) of the NGC 4559 X-10 counterpart is well fitted by a spectrum of an A…
Gaia DR2 reveals a very massive runaway star ejected from R136
Anderson, J.; Crowther, P. A.; Lennon, D. J. +14 more
A previous spectroscopic study identified the very massive O2 III star VFTS 16 in the Tarantula Nebula as a runaway star based on its peculiar line-of-sight velocity. We use the Gaia DR2 catalog to measure the relative proper motion of VFTS 16 and nearby bright stars to test if this star might have been ejected from the central cluster, R136, via …