Search Publications
Breaking Correlation in the Inflow Parameters of Interstellar Neutral Gas in Direct-sampling Observations
Möbius, E.; Schwadron, N. A.; Bzowski, M. +1 more
We analyze the reasons for the correlation between the temperature, direction, and speed of the interstellar neutral gas inflow into the heliosphere, obtained in analyses of observations performed by an onboard Interstellar Boundary Explorer (IBEX) instrument, IBEX-Lo. We point out that this correlation is the combined result of the inability to m…
A Study of 90 GHz Dust Emissivity on Molecular Cloud and Filament Scales
Hensley, Brandon; Friesen, Rachel; Sadavoy, Sarah +19 more
Recent observations from the MUSTANG2 instrument on the Green Bank Telescope have revealed evidence of enhanced long-wavelength emission in the dust spectral energy distribution (SED) in the Orion Molecular Cloud (OMC) 2/3 filament on 25″ (0.1 pc) scales. Here we present a measurement of the SED on larger spatial scales (map size 0.°5-3° or 3-20 p…
Anomalous Orbital Characteristics of the AQ Col (EC 05217-3914) System
von Hippel, T.; Silvotti, R.; Kilkenny, D. +6 more
AQ Col (EC 05217-3914) is one of the first detected pulsating subdwarf B (sdB) stars and has been considered to be a single star. Photometric monitoring of AQ Col reveals a pulsation timing variation with a period of 486 days, interpreted as time delay due to reflex motion in a wide binary formed with an unseen companion with expected mass larger …
Galactic Cosmic Rays at Mars and Venus: Temporal Variations from Hours to Decades Measured as the Background Signal of Onboard Microchannel Plates
Barabash, Stas; Nilsson, Hans; Holmström, Mats +8 more
A microchannel plate (MCP) is a component widely used for counting particles in space. Using the background counts from MCPs on the Mars Express and Venus Express orbiters-operating over 17 yr and 8 yr, respectively-we investigated the galactic cosmic ray (GCR) characteristics of the inner solar system. The MCP background counts at Mars and Venus,…
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…