Search Publications
A possible far-ultraviolet flux-dependent core mass function in NGC 6357
Giannetti, A.; Massi, F.; Wouterloot, J. G. A. +2 more
Context. NGC 6357 is a galactic star-forming complex (d ~ 1.7 kpc) composed of several HII regions, a few young stellar clusters, and giant molecular clouds. In particular, the HII regions G353.2+0.9, G353.1+0.6, and G353.2+0.7 are associated with three young clusters; the most prominent of these, Pismis 24, contains some of the most massive stars…
Detection of H2 in the TWA 7 System: A Probable Circumstellar Origin
France, Kevin; Johns-Krull, Christopher M.; Carpenter, John M. +4 more
Using HST-COS far-UV spectra, we have discovered warm molecular hydrogen in the TWA 7 system. TWA 7, a ~9 Myr old M2.5 star, has a cold debris disk and has previously shown no signs of accretion. Molecular hydrogen is expected to be extremely rare in a debris disk. While molecular hydrogen can be produced in starspots or the lower chromospheres of…
An investigation of planetary nebulae accompanying PG 1159 central stars, based on Gaia DR2 measurements
Ali, Alaa; Alharbi, Wedad R.
This article discusses the physical and kinematical characteristics of planetary nebulae accompanying PG 1159 central stars. The study is based on the parallax and proper motion measurements recently offered by the Gaia space mission. Two approaches were used to investigate the kinematical properties of the sample. The results revealed that most o…
Dynamics of nanodust in the vicinity of a stellar corona: Effect of plasma corotation
Czechowski, A.; Mann, I.
Context. In the vicinity of the Sun or other stars, the motion of the coronal and stellar wind plasma must include some amount of corotation, which could affect the dynamics of charged dust particles. In the case of the Sun, this region is now investigated in situ by the Parker Solar Probe. Charged dust particles coming from the vicinity of the Su…
SOFIA upGREAT/FIFI-LS Emission-line Observations of Betelgeuse during the Great Dimming of 2019/2020
Harper, Graham M.; Guinan, Edward F.; Fadda, Dario +12 more
We report NASA-DLR SOFIA upGREAT circumstellar [O I] 63.2 µm and [C II] 157.7 µm emission profiles and FIFI-LS [O I] 63.2 µm, [O I] 145.5 µm, and [C II] 157.7 µm fluxes obtained shortly after Betelgeuse's 2019/2020 Great Dimming event. Haas et al. noted a potential correlation between the [O I] 63.2 µm flux and …
A time-series VI study of the variable stars of the globular cluster NGC 6397
Arellano Ferro, A.; Calderón, J. H.; Lázaro, C. +4 more
We present a new time-series VI CCD photometry of the globular cluster NGC 6397, from which we obtained and analysed the light curves of 35 variables carefully identified in the cluster field. We assessed the membership of the variables with an astrometric analysis based on Gaia DR2 data. The cluster colour-magnitude diagram was differentially der…
Suzaku observations of Jovian diffuse hard X-ray emission
Miyoshi, Yoshizumi; Ezoe, Yuichiro; Ishikawa, Kumi +6 more
We report on results of systematic analyses of the entire three X-ray data sets of Jupiter taken by Suzaku in 2006, 2012, and 2014. Jovian diffuse hard X-ray emission was discovered by Suzaku in 2006 when the solar activity went toward its minimum. The diffuse emission was spatially consistent with the Jovian inner magnetosphere and was spectrally…
Dust dissipation timescales in the intermediate and outer regions of protoplanetary disks
Nakagawa, Takao; Kwon, Jungmi; Takita, Satoshi +2 more
Dust and gas in protoplanetary disks dissipate as central stars evolve. In order to estimate the dust dissipation timescales in the protoplanetary disks, we stacked the WISE 12 and 22, and the AKARI 90 µm survey images of known T Tauri stars and derived the average fluxes, well below the survey flux limit in the 90 µm band. We classifi…
X-Ray Flux and Spectral Variability of BL Lacertae Objects Mrk 421, Mrk 501, and 1ES1426+428 with Suzaku Satellite
Abdelbar, Ahmed M.; Beheary, M. M.; Saad, A. Ata +1 more
We present a detailed spectral study of Suzaku observations of three blazars (Mrk 421, Mrk 501, and 1ES1426+428). The X-ray properties of our sample are derived by extracting the BL Lacertae sample spectra, and fitted by five models. The fit was in the soft X-ray band (0.8 - 10.0 keV). These models give similar results. By comparing the fits from …
A Morphological Classification Model to Identify Unresolved PanSTARRS1 Sources. II. Update to the PS1 Point Source Catalog
Miller, A. A.; Hall, X. J.
We present an update to the PanSTARRS-1 Point Source Catalog (PS1 PSC), which provides morphological classifications of PS1 sources. The original PS1 PSC adopted stringent detection criteria that excluded hundreds of millions of PS1 sources from the PSC. Here, we adapt the supervised machine learning methods used to create the PS1 PSC and apply th…