Search Publications
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…
Diffuse X-ray emission around an ultraluminous X-ray pulsar
Wolter, Anna; Pintore, Fabio; Mereghetti, Sandro +17 more
Ultraluminous X-ray sources (ULXs) are extragalactic X-ray emitters located off-centre of their host galaxy and with a luminosity in excess of a few 1039 erg s-1, if emitted isotropically1,2. The discovery of periodic modulation revealed that in some ULXs the accreting compact object is a neutron star3-7…
NEPSC2, the North Ecliptic Pole SCUBA-2 survey: 850-µm map and catalogue of 850-µm-selected sources over 2 deg2
Hashimoto, Tetsuya; Kim, Seong Jin; Conselice, Christopher J. +27 more
We present an 850-µm mosaic map and extracted catalogue of submillimetre sources in the extended North Ecliptic Pole (NEP) region over about 2 deg2. The 850-µm map is constructed using newly obtained observations by SCUBA-2 at the East Asian Observatory's James Clerk Maxwell Telescope, carried out using the observatory's lar…
44Ti ejecta in young supernova remnants
Diehl, Roland; Greiner, Jochen; Siegert, Thomas +2 more
Context. Tracing unstable isotopes produced in supernova nucleosynthesis provides a direct diagnostic of supernova explosion physics. Theoretical models predict an extensive variety of scenarios, which can be constrained through observations of the abundant isotopes 56Ni and 44Ti. Direct evidence of the latter was previously …
The Importance of Star Formation Intensity in Lyα Escape from Green Pea Galaxies and Lyman Break Galaxy Analogs
Malhotra, Sangeeta; Butler, Nathaniel R.; Yang, Huan +2 more
We have studied ultraviolet images of 40 Green Pea galaxies and 15 local Lyman Break Galaxy Analogs to understand the relation between Lyα photon escape and central UV photometric properties. We measured star-formation intensity (SFI; star formation rate per unit area) from the central 250 pc region ( ${S}_{250\mathrm{pc}}$ ) using Cosmic Origins …