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NGC 2022, a case study of a multiple-shell planetary nebula
Chu, Y. -H.; Guerrero, M. A.; Toalá, J. A. +7 more
We present a detailed study of the physical properties, history of mass loss, and chemical abundances of the planetary nebula NGC 2022. New imaging observations obtained with the OAJ/JAST80 and NOT/ALFOSC confirm the presence of a faint ~88 arcsec halo surrounding a double-layered elliptical structure that consists of a bright 21.4 × 16.7 arcsec i…
Searching for single-frame rapid X-ray transients detected with Chandra
Feng, Hua; Zhang, Yijia
We propose a new method to identify rapid X-ray transients observed with focusing telescopes. They could be statistically significant if three or more photons are detected with Chandra in a single CCD frame within a point-spread-function region out of quiescent background. In the Chandra archive, 11 such events are discovered from regions without …
CO, H2O, and CH4 in the dusty atmosphere of a ≲5 Myr-old exoplanet
Gaidos, Eric; Hirano, Teruyuki
Very young massive planets are sufficiently luminous by their internal heat of formation to permit detailed studies, including spectroscopy of their atmospheres with large telescopes at sufficient resolution (λ/Δλ ≳ 1000) to identify major constituents to inform models of planet formation and early evolution. We obtained 1-2.4 µm (YJHK) spec…
Galaxy And Mass Assembly (GAMA): the dependence of star formation on surface brightness in low-redshift galaxies
Bremer, M. N.; Holwerda, B. W.; De Propris, R. +5 more
The star-formation rate in galaxies is well known to correlate with stellar mass (the 'star-forming main sequence'). Here, we extend this further to explore any additional dependence on galaxy surface brightness, a proxy for stellar mass surface density. We use a large sample of low-redshift (z ≤ 0.08) galaxies from the Galaxy And Mass Assembly su…
Jupiter's equatorial X-ray emissions over two solar cycles
Coates, A. J.; Branduardi-Raymont, G.; Dunn, W. R. +2 more
Jupiter's disc is bright in X-rays as H2 molecules in the atmosphere are very effective at scattering solar X-rays. K-shell fluorescence from carbon atoms in atmospheric methane is thought to also provide a minor contribution. XMM-Newton has now observed Jupiter over a span of nearly two solar cycles from 2003 to 2021, offering the oppo…
New constraints on decaying dark matter from INTEGRAL/SPI
Santangelo, A.; Ducci, L.; Malyshev, D. +1 more
Based on almost 20 yr of data collected by the high-resolution spectrometer SPI on board the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), we present constraints on a decaying dark matter particle undergoing a decay into two bodies, at least one of which is a photon, manifesting itself via a narrow line-like spectral feature. Our ON-…
Comparison of distance measurements to dust clouds using GRB X-ray haloes and 3D dust extinction
Tiengo, A.; Bošnjak, Ž.; Pintore, F. +3 more
X-ray photons from energetic sources such as gamma-ray bursts (GRBs) can be scattered on dust clouds in the Milky Way, creating a time-evolving halo around the GRB position. X-ray observations of such haloes allow the measurement of dust cloud distances in the Galaxy on which the scattering occurs. We present the first systematic comparison of the…
A colourful analysis: Probing the eclipse of the black hole and central engine in NGC 6814 using X-ray colour-colour grids
Miller, J. M.; Gallo, L. C.; Gonzalez, A. G. +1 more
Eclipsing of the X-ray emitting region in active galactic nuclei (AGN) is a potentially powerful probe to examine the AGN environment and absorber properties. Here, we study the eclipse data from the 2016 XMM-Newton observation of NGC 6814 using a colour-colour analysis. Colours (i.e. hardness ratios) can provide the advantage of better time resol…
Light and colour of cirrus, translucent, and opaque dust in the high-latitude area of LDN 1642
Haas, M.; Väisänen, P.; Lehtinen, K. +2 more
We have performed a 5-colour surface photometric study of the high-galactic-latitude area of dark nebula LDN 1642. Scattered light properties are presented of diffuse, translucent, and opaque dust over the range of 3500-5500 Å . Far infrared absolute photometry at 200 µm improves the precision of and provides a zero point to the extinction. The in…
TCP J18224935-2408280: a symbiotic star identified during outburst
Sonith, L. S.; Kamath, U. S.
TCP J18224935-2408280 was reported to be in outburst on 2021 May 19. Follow-up spectroscopic observations confirmed that the system was a symbiotic star. We present optical spectra obtained from the Himalayan Chandra Telescope during 2021-22. The early spectra were dominated by Balmer lines, He I lines and high ionization lines such as He II. In t…