Search Publications
Detection of the S(1) Rotational Line of H2 toward IRC+10216: A Simultaneous Measurement of the Mass-loss Rate and CO Abundance
Cernicharo, J.; Fonfría, J. P.; Richter, M. J. +2 more
We report the first detection of the S(1) pure rotational line of ortho-H2 at 17.04 µm in an asymptotic giant branch star, using observations of IRC+10216 with the Echelon-cross-echelle Spectrograph (EXES) mounted on the Stratospheric Observatory for Infrared Astronomy. This line, which was observed in a very high-sensitivity spec…
Spectroscopic and Imaging Observations of Spatially Extended Magnetic Reconnection in the Splitting of a Solar Filament Structure
Liu, Ying D.; Hu, Huidong; Peter, Hardi +2 more
On the Sun, Doppler shifts of bidirectional outflows from the magnetic-reconnection site have been found only in confined regions through spectroscopic observations. Without spatially resolved spectroscopic observations across an extended region, the distribution of reconnection and its outflows in the solar atmosphere cannot be made clear. Magnet…
Modeling the Luminosity-dependent Pulse Profile and Emission Geometry of SMC X-2 during a Giant Outburst
Laycock, Silas G. T.; Vasilopoulos, Georgios; Christodoulou, Dimitris M. +3 more
One of the brightest X-ray pulsars in the Small Magellanic Cloud is SMC X-2. During its most recent major outburst in 2015, this transient pulsar displayed significant changes in both its accretion state and magnetosphere, particularly when it entered the low-luminosity regime of subcritical accretion. Polestar is a pulse-profile modeling code tha…
XMM and NuSTAR Observations of an Optically Quiescent Quasar
Gandhi, Poshak; Stern, Daniel; Mainieri, Vincenzo +3 more
Optically quiescent quasars (OQQs) represent a recently systematized class of infrared-luminous active galactic nuclei (AGNs) that have galaxy-like optical continua. They may represent an interesting, brief phase in the AGN life cycle, e.g., either cocooned within high-covering-factor media or indicative of recent triggering, though their nature r…
The SDSS-Gaia View of the Color-Magnitude Relation for Blue Horizontal-branch Stars
Limberg, Guilherme; Rossi, Silvia; Perottoni, Hélio D. +3 more
We present an updated sample of blue horizontal-branch (BHB) stars selected from the photometric and spectroscopic data from Sloan Digital Sky Survey and its associated project Sloan Extension for Galactic Understanding and Exploration (SEGUE). With these data, we selected candidates for A-type stars in the color-color space and then a mixture mod…
Hard X-Ray Flares and Spectral Variability in NGC 4395 ULX1
Bachetti, Matteo; Rana, Vikram; Ghosh, Tanuman
We report the detection of flaring events in NGC 4395 ULX1, a nearby ultraluminous X-ray source (ULX), for the first time, using recent XMM-Newton observations. The flaring episodes are spectrally harder than the steady-emission intervals, resulting in higher fractional variability in the high-energy regime. A thin Keplerian and a slim accretion d…
Perfecting Our Set of Spectrophotometric Standard DA White Dwarfs
Rest, Armin; Matheson, Thomas; Raddi, Roberto +17 more
We verified for photometric stability a set of DA white dwarfs with Hubble Space Telescope magnitudes from the near-ultraviolet to the near-infrared and ground-based spectroscopy by using time-spaced observations from the Las Cumbres Observatory network of telescopes. The initial list of 38 stars was whittled to 32 final ones, which comprise a hig…
X-Ray and Radio Observations of Central Black Holes in Nearby Low-mass Early-type Galaxies: Preliminary Evidence for Low Eddington Fractions
Neumayer, Nadine; Strader, Jay; Seth, Anil C. +5 more
We present new radio and X-ray observations of two nearby (<4 Mpc) low-mass early-type galaxies with dynamically confirmed central black holes: NGC 5102 and NGC 205. NGC 5102 shows a weak nuclear X-ray source and has no core radio emission. However, for the first time we demonstrate that it shows luminous extended radio continuum emission in lo…
Discovery of a Filamentary Synchrotron Structure Connected to the Coherent Magnetic Field in the Outer Galaxy
Ricci, R.; Safi-Harb, S.; Kothes, R. +9 more
Using data from the Galactic Arecibo L-band Feed Array Continuum Transit Survey, we report the discovery of two previously unidentified, very compressed, thin, and straight polarized filaments approximately centered at Galactic coordinates, (l, b) = (182.°5, - 4.°0), which we call G182.5-4.0. Using data from the Isaac Newton Telescope Galactic Pla…
Detection of Stellar-like Abundance Anomalies in the Slow Solar Wind
Warren, Harry P.; Brooks, David H.; Baker, Deborah +2 more
The elemental composition of the Sun's hot atmosphere, the corona, shows a distinctive pattern that is different from the underlying surface or photosphere. Elements that are easy to ionize in the chromosphere are enhanced in abundance in the corona compared to their photospheric values. A similar pattern of behavior is often observed in the slow-…