Search Publications
Discovery of new low-excitation planetary nebulae
Zhang, Yong; Hsia, Chih-Hao
We report a multi-wavelength study of four new planetary nebula (PN) candidates selected from the INT/WFC Photometric Hα Survey of the Northern Galactic Plane (IPHAS) and Deep Sky Hunter (DSH) catalogues. We present mid-resolution optical spectra of these PNs. The PN status of our sample was confirmed by optical narrow-band images and mid-resoluti…
Magnetic pattern at supergranulation scale: the void size distribution
Berrilli, F.; Del Moro, D.; Scardigli, S.
The large-scale magnetic pattern observed in the photosphere of the quiet Sun is dominated by the magnetic network. This network, created by photospheric magnetic fields swept into convective downflows, delineates the boundaries of large-scale cells of overturning plasma and exhibits "voids" in magnetic organization. These voids include internetwo…
A thin diffuse component of the Galactic ridge X-ray emission and heating of the interstellar medium contributed by the radiation of Galactic X-ray binaries
Molaro, Margherita; Khatri, Rishi; Sunyaev, Rashid A.
We predict a thin diffuse component of the Galactic ridge X-ray emission (GRXE) arising from the scattering of the radiation of bright X-ray binaries (XBs) by the interstellar medium. This scattered component has the same scale height as that of the gaseous disk (~80 pc) and is therefore thinner than the GRXE of stellar origin (scale height ~130 p…
Orphan penumbrae: Submerging horizontal fields
Bellot Rubio, L. R.; Jurčák, J.; Sobotka, M.
Aims: We investigate the properties of orphan penumbrae, which are photospheric filamentary structures observed in active regions near polarity inversion lines that resemble the penumbra of regular sunspots but are not connected to any umbra.
Methods: We use Hinode data from the Solar Optical Telescope to determine the properties of orph…
The evolving spectrum of the planetary nebula Hen 2-260
Zijlstra, A. A.; van Hoof, P. A. M.; Hajduk, M. +3 more
Aims: We analysed the planetary nebula Hen 2-260 using optical spectroscopy and photometry. We compared our observations with the data from literature to search for evolutionary changes. We also searched for photomertic variability of the central star.
Methods: The object Hen 2-260 was observed with the SAAO 1.0 m telescope (photometry) …
A state-of-the-art analysis of the dwarf irregular galaxy NGC 6822
Hidalgo, S. L.; Bono, G.; Pietrinferni, A. +5 more
We present a detailed photometric study of the dwarf irregular galaxy NGC 6822 aimed at investigating the properties of its stellar populations and, in particular, the presence of stellar radial gradients. Our goal is to analyse the stellar populations in six fields, which cover the whole bar of this dwarf galaxy. We derived the quantitative star …
IP Eridani: A surprising long-period binary system hosting a He white dwarf
Jorissen, A.; Masseron, T.; Van Winckel, H. +3 more
We determine the orbital elements for the K0 IV + white dwarf (WD) system IP Eri, which appears to have a surprisingly long period of 1071 d and a significant eccentricity of 0.25. Previous spectroscopic analyses of the WD, based on a distance of 101 pc inferred from its Hipparcos parallax, yielded a mass of only 0.43 M⊙, implying it to…
Massive stars in the giant molecular cloud G23.3-0.3 and W41
Menten, Karl M.; Rich, R. Michael; MacKenty, John W. +7 more
Context. Young massive stars and stellar clusters continuously form in the Galactic disk, generating new Hii regions within their natal giant molecular clouds and subsequently enriching the interstellar medium via their winds and supernovae.
Aims: Massive stars are among the brightest infrared stars in such regions; their identification permi…
Proper motions for HST observations in three off-axis bulge fields
Rich, R. M.; Soto, M.; Kuijken, K. +3 more
Aims: This is the second in a series of papers that attempt to unveil the kinematic structure of the Galactic bulge through studying radial velocities and proper motions. We report here ~15 000 new proper motions for three low foreground-extinction off-axis fields of the Galactic bulge.
Methods: Proper motions were derived from a combina…
Understanding the dynamical structure of pulsating stars. HARPS spectroscopy of the δ Scuti stars ρ Puppis and DX Ceti
Guiglion, G.; Poretti, E.; Rainer, M. +4 more
Context. High-resolution spectroscopy is a powerful tool to study the dynamical structure of a pulsating star's atmosphere.
Aims: We aim at comparing the line asymmetry and velocity of the two δ Sct stars ρ Pup and DX Cet with previous spectroscopic data obtained on classical Cepheids and β Cep stars.
Methods: We obtained, analysed and d…