Search Publications
Near-infrared Spectroscopy of the Sun and Solar Analog Star HD 76151: Compiling an Extensive Line List in the Y, J, H, and K Bands
Bilir, Selçuk; Şahin, Timur; Şentürk, Sena Aleyna +2 more
Determining the physical nature of a star requires precise knowledge of its stellar atmospheric parameters, including effective temperature, surface gravity, and metallicity. This study presents a new atomic line list covering a broad spectral range (1–2.5 µm; YJHK bands) for iron (Fe) and α-elements (Ca, Mg, Ti, Si) to improve stellar param…
Millinovae: A New Class of Transient Supersoft X-Ray Sources without a Classical Nova Eruption
Udalski, Andrzej; Mróz, Przemek; Szymański, Michał K. +18 more
Some accreting binary systems containing a white dwarf (such as classical novae or persistent supersoft sources) are seen to emit low-energy X-rays with temperatures of ∼ 106 K and luminosities exceeding 1035 erg s‑1. These X-rays are thought to originate from nuclear burning on the white dwarf surface, either caus…
An Intermediate-mass Black Hole Hidden behind Thick Obscuration
Ricci, Claudio; Stern, Daniel; Pfeifle, Ryan W. +12 more
Recent models suggest approximately half of all accreting supermassive black holes (SMBHs; M BH ≳ 105 M ⊙) are expected to undergo intense growth phases behind Compton-thick (N H > 1.5 × 1024 cm‑2) veils of obscuring gas. However, despite being a viable source for the seeding of …
A Hot Mess: The Rich and Complex Soft Emitting Regions Surrounding the Reflection Dominated Flaring Central Engine of Mrk 1239
Komossa, S.; Gallo, L. C.; Grupe, D. +5 more
Previous X-ray works on Mrk 1239 have revealed a complex narrow-line Seyfert 1 that exhibits substantial absorption and strong emission from both collisionally ionized and photoionized plasmas. Here, we report on deep-pointed observations with XMM-Newton and NuSTAR, along with Swift monitoring, to understand the 0.3–30 keV continuum emission and t…
A Detailed Analysis of a Magnetic Island Observed by WISPR on Parker Solar Probe
Liewer, Paulett C.; Gallagher, Brendan M.; Linton, Mark G. +4 more
We present the identification and physical analysis of a possible magnetic island feature seen in white-light images observed by the Wide-field Imager for Solar Probe (WISPR) on board the Parker Solar Probe. The island is imaged by WISPR during Parker's second solar encounter on 2019 April 6, when Parker was ∼38 R ⊙ from the Sun's cente…
Imaging of the Vega Debris System Using JWST/MIRI
Rieke, George H.; Gáspár, András; Beichman, Charles +6 more
We present images of the Vega planetary debris disk obtained at 15.5, 23, and 25.5 µm with the Mid-Infrared Instrument on JWST. The debris system is remarkably symmetric, smooth, and centered accurately on the star. There is a broad Kuiper-belt-analog ring at ∼80–170 au that coincides with the planetesimal belt detected with the Atacama Larg…
Icarus Revisited: An Ancient, Metal-poor Accreted Stellar Stream in the Disk of the Milky Way
Vitali, Sara; Cignoni, Michele; Lattanzi, Mario G. +2 more
The search for accreted satellites in the Galactic disk is a challenging task, to which Gaia plays a crucial role in synergy with ground-based spectroscopic surveys. In 2021, P. Re Fiorentin et al. discovered five substructures with disk kinematics including Icarus. To gain more insight into the origin of Icarus as a remnant of a dwarf galaxy rath…
Discovery of Two Different Full Disk Evolutionary Patterns of M-type T Tauri Stars with LAMOST DR8
Zhao, Yongheng; Duan, Fuqing; Li, Guang-Wei +2 more
The full disk, full of gas and dust, determines the upper limit of planet masses, and its lifetime is critical for planet formation, especially for giant planets. In this work, we studied the evolutionary timescales of the full disks of T Tauri stars (TTSs) and their relations to accretion. Combined with Gaia EDR3, Two Micron All Sky Survey, and W…
Visual Orbits of Wolf–Rayet Stars. I. The Orbit of the Dust-producing Wolf–Rayet Binary WR 137 Measured with the CHARA Array
Moffat, Anthony F. J.; Monnier, John D.; Schaefer, Gail H. +19 more
Classical Wolf–Rayet (W-R) stars are the descendants of massive OB stars that have lost their hydrogen envelopes and are burning helium in their cores prior to exploding as Type Ib/c supernovae. The mechanisms for losing their hydrogen envelopes are either through binary interactions or through strong stellar winds potentially coupled with episodi…
Using Polar Faculae to Determine the Sun's High-latitude Rotation Rate. I. Techniques and Initial Measurements
Sheeley, Neil R.
This paper describes a new way of determining the high-latitude solar rotation rate statistically from simultaneous observations of many polar faculae. In this experiment, I extracted frames from a movie made previously from flat-fielded images obtained in the 6767 Å continuum during 1997–1998 February and used those frames to construct spacetime …