Search Publications
The MUSE Hubble Ultra Deep Field Survey. XIV. Evolution of the Lyα emitter fraction from z = 3 to z = 6
Bacon, Roland; Blaizot, Jérémy; Garel, Thibault +19 more
Context. The Lyα emitter (LAE) fraction, XLAE, is a potentially powerful probe of the evolution of the intergalactic neutral hydrogen gas fraction. However, uncertainties in the measurement of XLAE are still under debate.
Aims: Thanks to deep data obtained with the integral field spectrograph Multi Unit Spectroscopic Exp…
The ALPINE-ALMA [CII] survey. Small Lyα-[CII] velocity offsets in main-sequence galaxies at 4.4 < z < 6
Cimatti, A.; Pozzi, F.; Rodighiero, G. +30 more
Context. The Lyman-α line in the ultraviolet (UV) and the [CII] line in the far-infrared (FIR) are widely used tools to identify galaxies in the early Universe and to obtain insights into interstellar medium (ISM) properties in high-redshift galaxies. By combining data obtained with ALMA in band 7 at ∼320 GHz as part of the ALMA Large Program to I…
Sun-Heliosphere Observation-based Ionization Rates Model
McComas, D. J.; Bzowski, M.; Tokumaru, M. +1 more
The solar wind (SW) and the extreme ultraviolet (EUV) radiation modulate fluxes of interstellar and heliospheric particles inside the heliosphere both in time and in space. Understanding this modulation is necessary to correctly interpret measurements of particles of interstellar origin inside the heliosphere. We present a revision of heliospheric…
Ion-neutral Interactions and Nonequilibrium Ionization in the Solar Chromosphere
Martínez-Sykora, Juan; De Pontieu, Bart; Nóbrega-Siverio, Daniel +4 more
The thermal structure of the chromosphere is regulated through a complex interaction of various heating processes, radiative cooling, and the ionization degree of the plasma. Here, we study the impact on the thermal properties of the chromosphere when including the combined action of nonequilibrium ionization (NEI) of hydrogen and helium and ion-n…
Exploring open cluster properties with Gaia and LAMOST
Wu, Di; Chen, Li; Zhong, Jing +3 more
Context. In Gaia DR2, an unprecedented high level of precision has been reached at sub-milliarcsecond for astrometry and millimagnitudes for photometry. Using cluster members identified with the astrometry and photometry in Gaia DR2, we can obtain a reliable determination of cluster properties. However, because of the shortcomings of Gaia spectros…
Spatially Resolved Ultraviolet Spectroscopy of the Great Dimming of Betelgeuse
Dupree, Andrea K.; Guinan, Edward F.; Leike, Reimar +9 more
The bright supergiant Betelgeuse (Alpha Orionis, HD 39801) experienced a visual dimming during 2019 December and the first quarter of 2020, reaching an historic minimum 2020 February 7-13. During 2019 September-November, prior to the optical dimming event, the photosphere was expanding. At the same time, spatially resolved ultraviolet spectra usin…
An Extreme-precision Radial-velocity Pipeline: First Radial Velocities from EXPRES
Ong, J. M. Joel; Fischer, Debra A.; Buchhave, Lars A. +13 more
The EXtreme-PREcision Spectrograph (EXPRES) is an environmentally stabilized, fiber-fed, R = 137,500, optical spectrograph. It was recently commissioned at the 4.3 m Lowell Discovery Telescope near Flagstaff, Arizona. The spectrograph was designed with a target radial-velocity (RV) precision of 30 cm s-1. In addition to instrumental inn…
Two Views of the Radius Gap and the Role of Light Curve Fitting
Petigura, Erik A.
Recently, several groups have resolved a gap that bifurcates planets between the size of Earth and Neptune into two populations. The location and depth of this feature is an important signature of the physical processes that form and sculpt planets. In particular, planets residing in the radius gap are valuable probes of these processes as they ma…
An extremely energetic supernova from a very massive star in a dense medium
Bieryla, Allyson; Laher, Russ R.; Masci, Frank J. +14 more
The interaction of a supernova with a circumstellar medium (CSM) can dramatically increase the emitted luminosity by converting kinetic energy to thermal energy. In `superluminous' supernovae of type IIn—named for narrow hydrogen lines1 in their spectra—the integrated emission can reach2-6 ~1051 erg, attainable by …
The LX-Luv-Lradio relation and corona-disc-jet connection in optically selected radio-loud quasars
Brandt, W. N.; Xue, Y. Q.; Luo, B. +3 more
Radio-loud quasars (RLQs) are more X-ray luminous than predicted by the X-ray-optical/UV relation (i.e. $L_\mathrm{x}\propto L_\mathrm{uv}^\gamma$) for radio-quiet quasars (RQQs). The excess X-ray emission depends on the radio-loudness parameter (R) and radio spectral slope (αr). We construct a uniform sample of 729 optically selected R…