Search Publications
GD358: Three Decades of Observations for the In-depth Asteroseismology of a DBV Star
Kim, S. -L.; Hoyer, D.; Montgomery, M. H. +39 more
We report on the analysis of 34 years of photometric observations of the pulsating helium atmosphere white dwarf GD358. The complete data set includes archival data from 1982 to 2006, and 1195.2 hr of new observations from 2007 to 2016. From this data set, we extract 15 frequencies representing g-mode pulsation modes, adding 4 modes to the 11 mode…
Dynamo Wave Patterns inside of the Sun Revealed by Torsional Oscillations
Kosovichev, Alexander G.; Pipin, Valery V.
Torsional oscillations represent bands of fast and slow zonal flows around the Sun, which extend deep into the convection zone and migrate during solar cycles toward the equator following the sunspot “butterfly” diagram. Analysis of helioseismology data obtained in 1996-2018 for almost two solar cycles reveals zones of deceleration of the torsiona…
Damping of Propagating Kink Waves in the Solar Corona
Morton, Richard J.; Tiwari, Ajay K.; Régnier, Stéphane +1 more
Alfvénic waves have gained renewed interest since the existence of ubiquitous propagating kink waves were discovered in the corona. It has long been suggested that Alfvénic waves play an important role in coronal heating and the acceleration of the solar wind. To this effect, it is imperative to understand the mechanisms that enable their energy t…
Short-term Variability of Evolved Massive Stars with TESS
Davenport, James R. A.; Dorn-Wallenstein, Trevor Z.; Levesque, Emily M.
We present the first results from a study of Transiting Exoplanet Survey Satellite (TESS) Sector 1 and 2 light curves for eight evolved massive stars in the LMC: six yellow supergiants (YSGs) and two luminous blue variables (LBVs), including S Doradus. We use an iterative prewhitening procedure to characterize the short-timescale variability in al…
Evidence for a Massive Warm-Hot Circumgalactic Medium around NGC 3221
Nicastro, Fabrizio; Mathur, Smita; Gupta, Anjali +3 more
We report a 3.4σ detection of the warm-hot, massive, extended circumgalactic medium (CGM) around an L ⋆ star-forming spiral galaxy NGC 3221, using deep Suzaku observations. The temperature of the gas is 106.1 K, comparable to that of the Milky Way CGM. The spatial extent of the gas is at least 150 kpc. For a β-model of densit…
Possible Evidence for Cosmic-Ray Acceleration in the Type Ia SNR RCW 86: Spatial Correlation between TeV Gamma-Rays and Interstellar Atomic Protons
Rowell, G.; Fukui, Y.; Mitsuishi, I. +13 more
We present a detailed morphological study of TeV gamma-rays, synchrotron radiation, and interstellar gas in the young Type Ia supernova remnant (SNR) RCW 86. We find that the interstellar atomic gas shows good spatial correlation with the gamma-rays, indicating that the TeV gamma-rays from RCW 86 are likely predominantly of hadronic origin. In con…
Dust-to-gas Ratio Resurgence in Circumstellar Disks Due to the Formation of Giant Planets: The Case of HD 163296
Marzari, F.; Testi, L.; Polychroni, D. +1 more
The amount of dust present in circumstellar disks is expected to steadily decrease with age due to the growth from µm-sized particles to planetesimals and planets. Mature circumstellar disks, however, can be observed to contain significant amounts of dust and possess high dust-to-gas ratios. Using HD 163296 as our case study, we explore how …
Nonparametric Dark Energy Reconstruction Using the Tomographic Alcock-Paczynski Test
Sabiu, Cristiano G.; Park, Hyunbae; Li, Yun-He +7 more
The tomographic Alcock-Paczynski (AP) method can result in tight cosmological constraints by using small and intermediate clustering scales of the large-scale structure of the galaxy distribution. By focusing on the redshift dependence, the AP distortion can be distinguished from the distortions produced by the redshift space distortions. In this …
On the High-energy Emissions of Compact Objects Observed with INTEGRAL SPI: Event Selection Impact on Source Spectra and Scientific Results for the Bright Sources Crab Nebula, GS 2023+338 and MAXI J1820+070
Jourdain, Elisabeth; Roques, Jean-Pierre
The Spectrometer on INTEGRAL (SPI) instrument has observed the hard X-ray sky from 20 keV up to a few MeV for more than 15 yr. In this energy domain, the main emitters are compact objects for which SPI provides spectral information of prime interest. Recently, two transient sources reached very unusual flux levels and have been detected up to a fe…
Chemical and Kinematic Analysis of CN-strong Metal-poor Field Stars in LAMOST DR3
Shi, Jianrong; Fernández-Trincado, J. G.; Zamora, Olga +5 more
The large amount of chemical and kinematic information available in large spectroscopic surveys has inspired the search for chemically peculiar stars in the field. Though these metal-poor field stars ([Fe/H] < -1) are commonly enriched in nitrogen, their detailed spatial, kinematic, and chemical distributions suggest that various groups may exi…