Search Publications
The Most Ancient Spiral Galaxy: A 2.6-Gyr-old Disk with a Tranquil Velocity Field
Kewley, Lisa J.; Richard, Johan; Gupta, Anshu +7 more
We report an integral-field spectroscopic (IFS) observation of a gravitationally lensed spiral galaxy A1689B11 at redshift z = 2.54. It is the most ancient spiral galaxy discovered to date and the second kinematically confirmed spiral at z≳ 2. Thanks to gravitational lensing, this is also by far the deepest IFS observation with the highest spatial…
Plasma Beta Stratification in the Solar Atmosphere: A Possible Explanation for the Penumbra Formation
Bourdin, Ph. -A.
Plasma beta is an important and fundamental physical quantity in order to understand plasma dynamics, particularly in the context of magnetically active stars, because it tells about the domination of magnetic versus thermodynamic processes on the plasma motion. We estimate the value ranges of plasma beta in different regions within the solar atmo…
Interstellar-medium Mapping in M82 through Light Echoes around Supernova 2014J
Baade, Dietrich; Sparks, William B.; Wang, Lifan +10 more
We present multiple-epoch measurements of the size and surface brightness of the light echoes from supernova (SN) 2014J in the nearby starburst galaxy M82. Hubble Space Telescope (HST) ACS/WFC images were taken ∼277 and ∼416 days after B-band maximum in the filters F475W, F606W, and F775W. Observations with HST WFC3/UVIS images at epochs ∼216 and …
New Evidence for the Dynamical Decay of a Multiple System in the Orion Kleinmann-Low Nebula
Luhman, K. L.; Robberto, M.; Manara, C. F. +5 more
We have measured astrometry for members of the Orion Nebula Cluster with images obtained in 2015 with the Wide Field Camera 3 on board the Hubble Space Telescope. By comparing those data to previous measurements with the Near-Infrared Camera and Multi-Object Spectrometer on Hubble in 1998, we have discovered that a star in the Kleinmann-Low Nebula…
Multiwavelength Stellar Polarimetry of the Filamentary Cloud IC5146. I. Dust Properties
Wang, Jia-Wei; Lai, Shih-Ping; Eswaraiah, Chakali +3 more
We present optical and near-infrared stellar polarization observations toward the dark filamentary clouds associated with IC5146. The data allow us to investigate the dust properties (this paper) and the magnetic field structure (Paper II). A total of 2022 background stars were detected in the R c , I\prime , H, and/or K ban…
Charge States and FIP Bias of the Solar Wind from Coronal Holes, Active Regions, and Quiet Sun
Fu, Hui; Madjarska, Maria S.; Li, Bo +3 more
Connecting in situ measured solar-wind plasma properties with typical regions on the Sun can provide an effective constraint and test to various solar wind models. We examine the statistical characteristics of the solar wind with an origin in different types of source regions. We find that the speed distribution of coronal-hole (CH) wind is bimoda…
Searching for Interstellar {{\rm{C}}}_{60}^{+} Using a New Method for High Signal-to-noise HST/STIS Spectroscopy
Gull, T. R.; Lallement, R.; Najarro, F. +9 more
Due to recent advances in laboratory spectroscopy, the first optical detection of a very large molecule has been claimed in the diffuse interstellar medium (ISM): {{{C}}}60+ (ionized Buckminsterfullerene). Confirming the presence of this molecule would have significant implications regarding the carbon budget and chemical com…
Current and Future Constraints on Primordial Magnetic Fields
Feng, Chang; Reichardt, Christian L.; Sutton, Dylan R.
We present new limits on the amplitude of potential primordial magnetic fields (PMFs) using temperature and polarization measurements of the cosmic microwave background (CMB) from Planck, the BICEP2/Keck Array, Polarbear, and SPTpol. We reduce twofold the 95% confidence upper limit on the CMB anisotropy power due to a nearly scale-invariant PMF, w…
Spectroscopic Observations of Magnetic Reconnection and Chromospheric Evaporation in an X-shaped Solar Flare
Gan, W. Q.; Ding, M. D.; Li, Y. +3 more
We present observations of distinct UV spectral properties at different locations during an atypical X-shaped flare (SOL2014-11-09T15:32) observed by the Interface Region Imaging Spectrograph (IRIS). In this flare, four chromospheric ribbons appear and converge at an X-point where a separator is anchored. Above the X-point, two sets of non-coplana…
The Origins of UV-optical Color Gradients in Star-forming Galaxies at z ∼ 2: Predominant Dust Gradients but Negligible sSFR Gradients
Barro, Guillermo; Faber, S. M.; Tacchella, Sandro +13 more
The rest-frame UV-optical (I.e., NUV - B) color is sensitive to both low-level recent star formation (specific star formation rate—sSFR) and dust. In this Letter, we extend our previous work on the origins of NUV - B color gradients in star-forming galaxies (SFGs) at z∼ 1 to those at z∼ 2. We use a sample of 1335 large (semimajor axis radius {R}