Search Publications
Application of a Steady-state Accretion Disk Model to Spectrophotometry and High-resolution Spectra of Two Recent FU Ori Outbursts
Rodriguez, Antonio C.; Hillenbrand, Lynne A.
We apply a conventional accretion disk model to the FU Ori-type objects HBC 722 and Gaia 17bpi. Our base model is a steady-state, thin Keplerian disk featuring a modified Shakura-Sunyaev temperature profile, with each annulus radiating as an area-weighted spectrum given by a NextGen atmosphere at the appropriate temperature. We explore departures …
High-density disc reflection spectroscopy of low-mass active galactic nuclei
Fabian, A. C.; Pinto, C.; Gandhi, P. +13 more
The standard alpha-disc model predicts an anticorrelation between the density of the inner accretion disc and the black hole mass times square of the accretion rate, as seen in higher mass (MBH > 106 M⊙) active galactic nuclei (AGNs). In this work, we test the predictions of the alpha-disc model and study the pr…
The Fundamental Planes of black hole activity for radio-loud and radio-quiet quasars
Snios, Bradford; Siemiginowska, Aneta; Schwartz, Daniel A. +2 more
We examine the Fundamental Plane of black hole activity for correlations with redshift and radio loudness in both radio-loud and radio-quiet quasar populations. Sources are compiled from archival data of both radio-loud and radio-quiet quasars over redshifts 0.1 < z < 5.0 to produce a sample of 353 sources with known X-ray, radio, and black …
The Galactic Nova Rate: Estimates from the ASAS-SN and Gaia Surveys
Mukai, K.; Kochanek, C. S.; Hodgkin, S. T. +13 more
We present the first estimate of the Galactic nova rate based on optical transient surveys covering the entire sky. Using data from the All-Sky Automated Survey for Supernovae (ASAS-SN) and Gaia-the only two all-sky surveys to report classical nova candidates-we find 39 confirmed Galactic novae and 7 additional unconfirmed candidates discovered fr…
Interrogating Solar Flare Loop Models with IRIS Observations 1: Overview of the Models, and Mass flows
Kerr, Graham S.
Solar and stellar flares are transient yet dramatic events in the atmospheres of the Sun or stars, during which vast amounts of magnetic energy is liberated. This energy is subsequently transported through the solar atmosphere or into the heliosphere, and together with coronal mass ejections flares comprise a fundamental component of space weather…
The CARMENES search for exoplanets around M dwarfs. Two Saturn-mass planets orbiting active stars
Amado, P. J.; Caballero, J. A.; Pallé, E. +26 more
The CARMENES radial-velocity survey is currently searching for planets in a sample of 387 M dwarfs. Here we report on two Saturn-mass planets orbiting TYC 2187-512-1 (M* = 0.50 M⊙) and TZ Ari (M* = 0.15 M⊙), respectively. We obtained supplementary photometric time series, which we use along with spectros…
A Young, Low-density Stellar Stream in the Milky Way Disk: Theia 456
Kounkel, Marina; Covey, Kevin R.; Agüeros, Marcel A. +4 more
Our view of the variety of stellar structures pervading the local Milky Way has been transformed by the application of clustering algorithms to the Gaia catalog. In particular, several stellar streams have been recently discovered that are comprised of hundreds to thousands of stars and span several hundred parsecs. We analyze one such structure, …
Resolving the H I in damped Lyman α systems that power star formation
Rigby, Jane R.; Sharon, Keren; Rizzi, Luca +10 more
Reservoirs of dense atomic gas (primarily hydrogen) contain approximately 90 per cent of the neutral gas at a redshift of 3, and contribute to between 2 and 3 per cent of the total baryons in the Universe1-4. These `damped Lyman α systems'—so called because they absorb Lyman α photons within and from background sources—have been studied…
The eROSITA Final Equatorial-Depth Survey (eFEDS). Presenting the demographics of X-ray emission from normal galaxies
Haberl, F.; Hornschemeier, A. E.; Ptak, A. +17 more
Context. The eROSITA Final Equatorial Depth Survey (eFEDS), completed in survey mode during the calibration and performance verification phase of the eROSITA instrument on Spectrum Roentgen Gamma, delivers data at and beyond the final depth of the 4-yr eROSITA all-sky survey (eRASS:8), f0.5-2 keV = 1.1 × 10−14 erg s−1
Haro 11 - Untying the knots of the nuclear starburst
Östlin, G.; Hayes, M.; Smith, L. J. +7 more
Star formation is a clustered process that regulates the structure and evolution of galaxies. We investigate this process in the dwarf galaxy Haro 11, forming stars in three knots (A, B, and C). The exquisite resolution of HST imaging allows us to resolve the starburst into tens of bright star clusters. We derive masses between 105 and …