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Cool white dwarfs as standards for infrared observations
Bohlin, Ralph C.; Gentile Fusillo, Nicola Pietro; Kalirai, Jason S. +2 more
In the era of modern digital sky surveys, uncertainties in the flux of stellar standards are commonly the dominant systematic error in photometric calibration and can often affect the results of higher level experiments. The Hubble Space Telescope (HST) spectrophotometry, which is based on computed model atmospheres for three hot (Teff …
Entropy-driven winds: Outflows and fountains lifted gently by buoyancy
Kruijssen, J. M. Diederik; Keller, Benjamin W.; Wadsley, James W.
We present a new theoretical framework for using entropy to understand how outflows driven by supernovae are launched from disc galaxies: via continuous, buoyant acceleration through the circumgalactic medium (CGM). When young star clusters detonate supernovae in the interstellar medium (ISM) of a galaxy, they generate hot, diffuse bubbles that pu…
GeV γ-Ray Emission from M33 and Arp 299
Liu, Ruo-Yu; Zhang, Hai-Ming; Wang, Xiang-Yu +1 more
Star-forming galaxies are huge reservoirs of cosmic rays (CRs) and these CRs convert a significant fraction of their energy into γ-rays by colliding with the interstellar medium (ISM). Several nearby star-forming galaxies have been detected in GeV-TeV γ-rays. It is also found that the γ-ray luminosities in 0.1-100 GeV correlate well with indicator…
MAXIMASK and MAXITRACK: Two new tools for identifying contaminants in astronomical images using convolutional neural networks
Bertin, E.; Bouy, H.; Paillassa, M.
In this work, we propose two convolutional neural network classifiers for detecting contaminants in astronomical images. Once trained, our classifiers are able to identify various contaminants, such as cosmic rays, hot and bad pixels, persistence effects, satellite or plane trails, residual fringe patterns, nebulous features, saturated pixels, dif…
The evolution of neutral hydrogen over the past 11 Gyr via H I 21 cm absorption
Bolatto, Alberto D.; Leroy, Adam K.; Grasha, Kathryn +1 more
We present the results of a blind search for intervening H I 21 cm absorption towards 260 radio sources in the redshift range 0 < z < 2.74 with the Green Bank Telescope. The survey has the sensitivity to detect sub-damped Ly α (DLA) systems for H I spin temperatures Ts/f = 100 K, and despite the successful re-detection of 10 known…
Two Wolf-Rayet stars at the heart of colliding-wind binary Apep
Callingham, J. R.; Crowther, P. A.; Marcote, B. +4 more
Infrared imaging of the colliding-wind binary Apep has revealed a spectacular dust plume with complicated internal dynamics that challenges standard colliding-wind binary physics. Such challenges can be potentially resolved if a rapidly rotating Wolf-Rayet star is located at the heart of the system, implicating Apep as a Galactic progenitor system…
Modelling solar irradiance from ground-based photometric observations
Chatzistergos, Theodosios; Ermolli, Ilaria; Giorgi, Fabrizio +2 more
Total solar irradiance (TSI) has been monitored from space since 1978, i.e. for about four solar cycles. The measurements show a prominent variability in phase with the solar cycle, as well as fluctuations on timescales shorter than a few days. However, the measurements were done by multiple and usually relatively short-lived missions. The differe…
Angular Expansion of Nova Shells
Guerrero, M. A.; Toalá, J. A.; Santamaría, E. +4 more
Nova shells can provide important information on their distance, their interactions with circumstellar and interstellar media, and the evolution in morphology of the ejecta. We have obtained narrowband images of a sample of five nova shells, namely DQ Her, FH Ser, T Aur, V476 Cyg, and V533 Her, with ages ranging from 50 to 130 yr. These images hav…
The First Extensive Spectroscopic Study of Young Stars in the North America and Pelican Nebulae
Fang, Min; Herczeg, Gregory J.; Wang, Hongchi +5 more
We present a spectroscopic survey of over 3400 potential members in the North America and Pelican Nebulae (NAP) using several low-resolution (R ≈ 1300-2000) spectrographs: Palomar/Norris, WIYN/Hydra, Keck/DEep Imaging Multi-Object Spectrograph (DEIMOS), and the Multiple Mirror Telescope (MMT)/Hectospec. We identify 580 young stars as likely member…
A New Likely Redback Millisecond Pulsar Binary with a Massive Neutron Star: 4FGL J2333.1-5527
Strader, Jay; Dage, Kristen C.; Chomiuk, Laura +7 more
We present the discovery of a likely new redback millisecond pulsar (MSP) binary associated with the Fermi γ-ray source 4FGL J2333.1-5527. Using optical photometric and spectroscopic observations from the Southern Astrophysical Research telescope, we identify a low-mass, main-sequence-like companion in a 6.9 hr, highly inclined orbit around a susp…