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GD 424 - a helium-atmosphere white dwarf with a large amount of trace hydrogen in the process of digesting a rocky planetesimal
Redfield, Seth; Gänsicke, Boris T.; Rodríguez-Gil, Pablo +5 more
The photospheric metal pollution of white dwarfs is now well established as the signature of the accretion of planetary debris. However, the origin of the trace hydrogen detected in many white dwarfs with helium atmospheres is still debated. Here, we report the analysis of GD 424: a metal-polluted, helium-atmosphere white dwarf with a large amount…
Understanding Polarized Dust Emission from ρ Ophiuchi A in Light of Grain Alignment and Disruption by Radiative Torques
Soam, Archana; Hoang, Thiem; Lee, Hyeseung +5 more
The alignment of dust grains with the ambient magnetic field produces polarization of starlight as well as thermal dust emission. Using the archival SOFIA/HAWC+ polarimetric data observed toward the ρ Ophiuchus (Oph) A cloud hosted by a B star at 89 and 154 µm, we find that the fractional polarization of thermal dust emission first increases…
Time and Charge-sign Dependence of the Heliospheric Modulation of Cosmic Rays
Potgieter, M. S.; Aslam, O. P. M.; Bisschoff, D. +4 more
Simultaneous and continuous observations of galactic cosmic-ray electrons (e-) and positrons (e+) from the PAMELA and AMS02 space experiments are most suitable for numerical modeling studies of the heliospheric modulation of these particles below 50 GeV. A well-established comprehensive three-dimensional modulation model is a…
The Source of Leaking Ionizing Photons from Haro11: Clues from HST/COS Spectroscopy of Knots A, B, and C
Cannon, John M.; Hayes, Matthew; Östlin, Göran +15 more
Understanding the escape of ionizing (Lyman continuum) photons from galaxies is vital for determining how galaxies contributed to reionization in the early universe. While directly detecting the Lyman continuum from high-redshift galaxies is impossible due to the intergalactic medium, low-redshift galaxies in principle offer this possibility but r…
Circumstellar Medium Constraints on the Environment of Two Nearby Type Ia Supernovae: SN 2017cbv and SN 2020nlb
Swift, Jonathan J.; Galbany, L.; Brown, P. J. +24 more
We present deep Chandra X-ray observations of two nearby Type Ia supernovae, SN 2017cbv and SN 2020nlb, which reveal no X-ray emission down to a luminosity LX ≲ 5.3 × 1037 and ≲ 5.4 × 1037 erg s-1 (0.3-10 keV), respectively, at ~16-18 days after the explosion. With these limits, we constrain the pre-expl…
Sulfuric acid vapor and sulfur dioxide in the atmosphere of Venus as observed by the Venus Express radio science experiment VeRa
Pätzold, M.; Bird, M. K.; Häusler, B. +4 more
The Venus Express radio science experiment VeRa provided more than 900 neutral atmospheric profiles between the years 2006 and 2014. About 800 of these could be used for an analysis of the radio signal absorption at X-Band (wavelength: 3.6 cm), which is mainly caused by sulfuric acid vapor within the Venus atmosphere. The absorptivity profiles wer…
The EXTraS project: Exploring the X-ray transient and variable sky
Salvaterra, R.; Haberl, F.; Greiner, J. +29 more
Temporal variability in flux and spectral shape is ubiquitous in the X-ray sky and carries crucial information about the nature and emission physics of the sources. The EPIC instrument on board the XMM-Newton observatory is the most powerful tool for studying variability even in faint sources. Each day, it collects a large amount of information ab…
The evolution of gas-phase metallicity and resolved abundances in star-forming galaxies at z ≈ 0.6-1.8
Smail, Ian; Bunker, Andrew J.; Swinbank, A. M. +10 more
We present an analysis of the chemical abundance properties of ≈650 star-forming galaxies at $z$ ≈ 0.6-1.8. Using integral-field observations from the K-band multi-object spectrograph (KMOS), we quantify the [N II]/H α emission-line ratio, a proxy for the gas-phase oxygen abundance within the interstellar medium. We define the stellar mass-metalli…
Multicolour photometry and Gaia EDR3 astrometry of two couples of binary clusters (NGC 5617 and Trumpler 22) and (NGC 3293 and NGC 3324)
Bisht, D.; Rangwal, Geeta; Yadav, R. K. S. +5 more
This paper presents a comprehensive analysis of two pairs of binary clusters (NGC 5617 and Trumpler 22) and (NGC 3293 and NGC 3324) located in the fourth quadrant of our Galaxy. For this purpose, we use different data taken from VVV survey, WISE, VPHAS, APASS, and GLIMPSE along with Gaia EDR3 astrometric data. We identified 584, 429, 692, and 273 …
Discovery of a Radio Halo (and Relic) in a M500<2×1014 M⊙ Cluster
Di Gennaro, G.; Brunetti, G.; Rossetti, M. +12 more
Radio halos are diffuse synchrotron sources observed in dynamically unrelaxed galaxy clusters. Current observations and models suggest that halos trace turbulent regions in the intracluster medium where mildly relativistic particles are reaccelerated during cluster mergers. Due to the higher luminosities and detection rates with increasing cluster…