Search Publications
The Origin of the Unfocused XMM-Newton Background, Its Variability, and Lessons Learned for ATHENA
Tiengo, Andrea; De Luca, Andrea; Marelli, Martino +7 more
We analyzed the unexposed to the sky (outFOV) region of the MOS2 detector on board XMM-Newton covering 15 yr of data amounting to 255 Ms. We show convincing evidence that the origin of the unfocused background in XMM-Newton is due to energetic protons, electrons, and hard X-ray photons. Galactic cosmic rays are the main contributors as shown by th…
Solar Polar Magnetic Fields: Comparing Full-disk and High-resolution Spectromagnetograph Data
Petrie, Gordon J. D.
This is the first systematic comparison between photospheric polar magnetic field data from a full-disk synoptic observing program, the National Solar Observatory's Synoptic Optical Long-term Investigations of the Sun Vector Spectromagnetograph (SOLIS/VSM), and a high-resolution vector spectromagnetograph, the Hinode Solar Optical Telescope Spectr…
Predicting the Geoeffectiveness of CMEs Using Machine Learning
Besliu-Ionescu, Diana; Paraschiv, Alin Razvan; Pricopi, Andreea-Clara +1 more
Coronal mass ejections (CMEs) are the most geoeffective space weather phenomena, being associated with large geomagnetic storms, and having the potential to cause disturbances to telecommunications, satellite network disruptions, and power grid damage and failures. Thus, considering these storms' potential effects on human activities, accurate for…
Ultraviolet Spectroscopy and TARDIS Models of the Broad-lined Type Ic Supernova 2014ad
Foley, Ryan J.; Modjaz, Maryam; Garnavich, Peter +11 more
Few published ultraviolet (UV) spectra exist for stripped-envelope supernovae and none to date for broad-lined Type Ic supernovae (SNe Ic-bl). These objects have extremely high ejecta velocities and are the only supernova type directly linked to gamma-ray bursts (GRBs). Here we present two epochs of HST/STIS spectra of the SN Ic-bl 2014ad, the fir…
A Comparison of Solar X-Ray Flare Timescales and Peak Temperatures with Associated Coronal Mass Ejections
Kahler, S. W.; Ling, A. G.
Recent work has shown that plots of solar flare X-ray peak temperatures, Tm, versus log peak fluxes, Fp, show statistically significant separations of lower Tm flares with fast (Vcme ≥ 1000 km s-1) and wide (Wcme = 360°) strong coronal mass ejections (CMEs) from higher Tm flares with no CMEs or slow (Vcme < 1000 km s-1) or…
Meta-analysis of Photometric and Asteroseismic Measurements of Stellar Rotation Periods: The Lomb–Scargle Periodogram, Autocorrelation Function, and Wavelet and Rotational Splitting Analysis for 92 Kepler Asteroseismic Targets
Suto, Yasushi; Benomar, Othman; Lu, Yuting +1 more
We perform intensity variability analyses (photometric analyses: the Lomb–Scargle periodogram, autocorrelation, and wavelet) and asteroseismic analysis of 92 Kepler solar-like main-sequence stars to understand the reliability of the measured stellar rotation periods. We focus on the 70 stars without reported stellar companions, and classify them i…
Absorption Line Search through Three Local Group Dwarf Galaxy Halos
Bregman, Joel N.; Qu, Zhijie
Dwarf galaxies are missing nearly all of their baryons and metals from the stellar disk, which are presumed to be in a bound halo or expelled beyond the virial radius. The virial temperature for galaxies with M h ~ 109-1010 M ⊙ is similar to the collisional ionization equilibrium temperature for the C IV…
A Massive, Dusty, HI Absorption-Selected Galaxy at z ≈ 2.46 Identified in a CO Emission Survey
Walter, F.; Prochaska, J. X.; Revalski, M. +4 more
We report a NOrthern Extended Millimeter Array (NOEMA) and Atacama Large Millimeter/submillimeter Array search for redshifted CO emission from the galaxies associated with seven high-metallicity ([M/H] ≥ -1.03) damped Lyα absorbers (DLAs) at z ≈ 1.64-2.51. Our observations yielded one new detection of CO(3-2) emission from a galaxy at z = 2.4604 u…
Discovery of NES, an Extended Tidal Structure in the Northeast of the Large Magellanic Cloud
Cignoni, Michele; Ripepi, Vincenzo; Tosi, Monica +4 more
We report on the discovery of a new diffuse stellar substructure protruding for >5° from the northeastern rim of the LMC disk. The structure, which we dub the northeast structure (NES), was identified by applying a Gaussian mixture model to a sample of strictly selected candidate members of the Magellanic System, extracted from the Gaia EDR3 ca…
Slowly Cooling White Dwarfs in NGC 6752
Cadelano, Mario; Pallanca, Cristina; Dalessandro, Emanuele +6 more
Recently, a new class of white dwarfs ("slowly cooling WDs") has been identified in the globular cluster M13. The cooling time of these stars is increased by stable thermonuclear hydrogen burning in their residual envelope. These WDs are thought to be originated by horizontal branch (HB) stars populating the HB blue tail that skipped the asymptoti…