Search Publications
Asteroseismic radii of dwarfs: new accuracy constraints from Gaia DR2 parallaxes
Silva Aguirre, Victor; Sahlholdt, Christian L.
Precise stellar masses and radii can be determined using asteroseismology, but their accuracy must be tested against independent estimates. Using radii derived from Gaia DR2 parallaxes, we test the accuracy of asteroseismic radii for a sample of 93 dwarfs based on both individual frequency fitting and the seismic scaling relations. Radii from freq…
An Iwasawa-Taniguchi effect for Compton-thick active galactic nuclei
Gandhi, Poshak; Ricci, Claudio; Stern, Daniel +4 more
We present the first study of an Iwasawa-Taniguchi/`X-ray Baldwin' effect for Compton-thick active galactic nuclei (AGN). We report a statistically significant anticorrelation between the rest-frame equivalent width (EW) of the narrow core of the neutral Fe Kα fluorescence emission line, ubiquitously observed in the reflection spectra of obscured …
Cross-calibration of CO- versus dust-based gas masses and assessment of the dynamical mass budget in Herschel-SDSS Stripe82 galaxies
Saintonge, Amélie; Wuyts, Stijn; Förster Schreiber, Natascha M. +7 more
We present a cross-calibration of CO- and dust-based molecular gas masses at z ≤ 0.2. Our results are based on a survey with the IRAM 30-m telescope collecting CO(1-0) measurements of 78 massive (logM⋆/M⊙> 10) galaxies with known gas-phase metallicities and with IR photometric coverage from Wide-field Infrared Survey Explo…
Helium abundance and speed difference between helium ions and protons in the solar wind from coronal holes, active regions, and quiet Sun
Fu, Hui; Madjarska, Maria S.; Li, Bo +2 more
Two main models have been developed to explain the mechanisms of release, heating, and acceleration of the nascent solar wind, the wave-turbulence-driven (WTD) models and reconnection-loop-opening (RLO) models, in which the plasma release processes are fundamentally different. Given that the statistical observational properties of helium ions prod…
A SITELLE view of M31's central region - I. Calibrations and radial velocity catalogue of nearly 800 emission-line point-like sources
Drissen, Laurent; Martin, Thomas B.; Melchior, Anne-Laure
We present a detailed description of the wavelength, astrometric and photometric calibration plan for SITELLE, the imaging Fourier transform spectrometer attached to the Canada-France-Hawaii telescope, based on observations of a red (647-685 nm) data cube of the central region (11 arcmin × 11 arcmin) of M 31. The first application, presented in th…
Young star clusters in nearby molecular clouds
Garmire, G. P.; Getman, K. V.; Kuhn, M. A. +3 more
The SFiNCs (Star Formation in Nearby Clouds) project is an X-ray/infrared study of the young stellar populations in 22 star-forming regions with distances ≲ 1 kpc designed to extend our earlier MYStIX (Massive Young Star-Forming Complex Study in Infrared and X-ray) survey of more distant clusters. Our central goal is to give empirical constraints …
The gravitational redshift of Sirius B
Barstow, M. A.; Holberg, J. B.; Casewell, S. L. +3 more
Einstein's general theory of relativity predicts that the light from stars will be gravitationally shifted to longer wavelengths. We previously used this effect to measure the mass of the white dwarf Sirius B from the wavelength shift observed in its Hα line based on spectroscopic data from the Space Telescope Imaging Spectrograph (STIS) on the Hu…
The COS-AGN survey: revealing the nature of circumgalactic gas around hosts of active galactic nuclei
Ellison, Sara L.; Tumlinson, Jason; Schaye, Joop +4 more
Active galactic nuclei (AGN) are thought to play a critical role in shaping galaxies, but their effect on the circumgalactic medium (CGM) is not well studied. We present results from the COS-AGN survey: 19 quasar sightlines that probe the CGM of 20 optically selected AGN host galaxies with impact parameters 80<ρimp<300 kpc. Absorp…
A disrupted molecular torus around Eta Carinae as seen in 12CO with ALMA
Smith, Nathan; Ginsburg, Adam; Bally, John
We present Atacama Large Millimeter Array (ALMA) observations of 12CO 2-1 emission from circumstellar material around the massive star Eta Carinae (η Car). These observations reveal new structural details about the cool equatorial torus located ∼4000 au from the star. The CO torus is not a complete azimuthal loop, but rather, is missing…
The dusty aftermath of SN Hunt 248: merger-burst remnant?
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Fox, Ori D. +3 more
SN Hunt 248 was classified as a non-terminal eruption (a supernova 'impostor') from a directly identified and highly variable cool hypergiant star. The 2014 outburst achieved peak luminosity equivalent to that of the historic eruption of luminous blue variable (LBV) η Car, and exhibited a multipeaked optical light curve which rapidly faded after ∼…