Search Publications
Disk Illumination and Jet Variability of the Herbig Ae Star HD 163296 Using Multi-epoch HST/STIS Optical, Near-IR, and Radio Imagery and Spectroscopy
Fukagawa, Misato; Sitko, Michael L.; Grady, Carol A. +3 more
We present two new epochs of Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph coronagraphic imaging, along with multi-epoch optical, near-IR, and radio monitoring, of the HD 163296 system. We find that ansae features identified in earlier-epoch HST imagery are a fourth ring that resides at a semimajor axis distance of 3"25 (330 au…
Properties of Solar Rossby Waves from Normal Mode Coupling and Characterizing Its Systematics
Mandal, Krishnendu; Hanasoge, Shravan
Rossby waves play an important role in mediating the angular momentum of rotating spherical fluids, creating weather on Earth and tuning exoplanet orbits in distant stellar systems. Their recent discovery in the solar convection zone provides an exciting opportunity to appreciate the detailed astrophysics of Rossby waves. Large-scale Rossby waves …
Using Data Imputation for Signal Separation in High-contrast Imaging
Debes, John H.; Duchêne, Gaspard; Perrin, Marshall D. +5 more
To characterize circumstellar systems in high-contrast imaging, the fundamental step is to construct a best point-spread function (PSF) template for the noncircumstellar signals (I.e., starlight and speckles) and separate it from the observation. With existing PSF construction methods, the circumstellar signals (e.g., planets, circumstellar disks)…
Stellar Cores in the Sh 2-305 H II Region
Pandey, Rakesh; Sharma, Saurabh; Panwar, Neelam +6 more
Using our deep optical and near-infrared photometry along with multiwavelength archival data, we here present a detailed study of the Galactic H II region Sh 2-305 to understand the star/star-cluster formation. On the basis of excess infrared emission, we have identified 116 young stellar objects (YSOs) within a field of view of ∼18'5 × 18'5 aroun…
An ALMA Survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS Field: The Far-infrared/Radio Correlation for High-redshift Dusty Star-forming Galaxies
Smail, I.; Thomson, A. P.; Scott, D. +17 more
We study the radio properties of 706 submillimeter galaxies (SMGs) selected at 870 µm with the Atacama Large Millimeter Array from the SCUBA-2 Cosmology Legacy Survey map of the Ultra Deep Survey field. We detect 273 SMGs at >4σ in deep Karl G. Jansky Very Large Array 1.4 GHz observations, of which a subset of 45 SMGs are additionally det…
Application of Synoptic Magnetograms to Global Solar Activity Forecast
Kitiashvili, I. N.
Synoptic magnetograms provide us with knowledge about the evolution of magnetic fields on the solar surface and present important information for forecasting future solar activity. In this work, poloidal and toroidal magnetic field components derived from synoptic magnetograms are assimilated, using the Ensemble Kalman Filter method, into a mean-f…
HST Grism-derived Forecasts for Future Galaxy Redshift Surveys
Bagley, Micaela B.; Scarlata, Claudia; Mehta, Vihang +8 more
The mutually complementary Euclid and Roman galaxy redshift surveys will use Hα- and [O III]-selected emission-line galaxies (ELGs) as tracers of the large-scale structure at 0.9 ≲ z ≲ 1.9 (Hα) and 1.5 ≲ z ≲ 2.7 ([O III]). It is essential to have a reliable and sufficiently precise knowledge of the expected numbers of Hα-emitting galaxies in the s…
Model-independent Estimations for the Cosmic Curvature from the Latest Strong Gravitational Lensing Systems
Li, Zhengxiang; Zhou, Huan
Model-independent measurements for the cosmic spatial curvature, which is related to the nature of cosmic spacetime geometry, play an important role in cosmology. On the basis of the distance sum rule in the Friedmann-Lemaître-Robertson-Walker metric, (distance ratio) measurements of strong gravitational lensing (SGL) systems, together with distan…
Monitoring the Spatio-temporal Evolution of a Reconnection X-line in Space
Vaivads, A.; Wang, Z.; Cao, J. B. +3 more
Inherently, magnetic reconnection—the process responsible for stellar flares and magnetospheric substorms—is very dynamic in space, owing to magnetic fluctuations and unsteady inflows. However, this process was always explained as a static picture in spacecraft measurements, neglecting the temporal evolution. This picture is not correct. Here we p…
Sun-as-a-star Spectral Irradiance Observations of Transiting Active Regions
Toriumi, Shin; Cheung, Mark C. M.; DeRosa, Marc L. +3 more
Major solar flares are prone to occur in active-region (AR) atmospheres associated with large, complex, dynamically evolving sunspots. This points to the importance of monitoring the evolution of starspots, not only in visible but also in ultraviolet (UV) and X-rays, in understanding the origin and occurrence of stellar flares. To this end, we per…