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Forever young white dwarfs: When stellar ageing stops
Córsico, Alejandro H.; Rebassa-Mansergas, Alberto; Althaus, Leandro G. +5 more
White dwarf stars are the most common end point of stellar evolution. The ultramassive white dwarfs are of special interest as they are related to type Ia supernovae explosions, merger events, and fast radio bursts. Ultramassive white dwarfs are expected to harbour oxygen-neon (ONe) cores as a result of single standard stellar evolution. However, …
Introducing piXedfit: A Spectral Energy Distribution Fitting Code Designed for Resolved Sources
Wu, Po-Feng; Lin, Yen-Ting; Abdurro'uf +1 more
We present piXedfit, pixelized spectral energy distribution (SED) fitting, a Python package that provides tools for analyzing spatially resolved properties of galaxies using multiband imaging data alone or in combination with integral field spectroscopy (IFS) data. It has six modules that can handle all tasks in the spatially resolved SED fitting.…
XMM-Newton campaign on the ultraluminous X-ray source NGC 247 ULX-1: outflows
Fabian, A. C.; Pinto, C.; D'Aì, A. +13 more
Most ultraluminous X-ray sources (ULXs) are believed to be powered by super-Eddington accreting neutron stars and, perhaps, black holes. Above the Eddington rate the disc is expected to thicken and to launch powerful winds through radiation pressure. Winds have been recently discovered in several ULXs. However, it is yet unclear whether the thicke…
The multiwavelength properties of red QSOs: Evidence for dusty winds as the origin of QSO reddening
Alexander, D. M.; Bowler, R. A. A.; Stalevski, M. +11 more
Fundamental differences in the radio properties of red quasars (QSOs), as compared to blue QSOs, have been recently discovered, positioning them as a potential key population in the evolution of galaxies and black holes across cosmic time. To elucidate the nature of these objects, we exploited a rich compilation of broad-band photometry and spectr…
Primordial black holes and secondary gravitational waves from chaotic inflation
Gao, Qing
Chaotic inflation is inconsistent with the observational constraint at 68% CL. Here, we show that the enhancement mechanism with a peak function in the noncanonical kinetic term not only helps the chaotic model V(ϕ) = V0ϕ1/3 satisfy the observational constraint at large scales but also enhances the primordial scalar power spe…
The contribution of N-rich stars to the Galactic stellar halo using APOGEE red giants
Bovy, Jo; Cunha, Katia; Majewski, Steven R. +13 more
The contribution of dissolved globular clusters (GCs) to the stellar content of the Galactic halo is a key constraint on models for GC formation and destruction, and the mass assembly history of the Milky Way. Earlier results from APOGEE pointed to a large contribution of destroyed GCs to the stellar content of the inner halo, by as much as 25 ${{…
Low-mass low-metallicity AGB stars as an efficient i-process site explaining CEMP-rs stars
Jorissen, A.; Escorza, A.; Masseron, T. +5 more
Context. Among carbon-enhanced metal-poor (CEMP) stars, some are found to be enriched in slow-neutron capture (s-process) elements (and are then tagged CEMP-s), some have overabundances in rapid-neutron capture (r-process) elements (tagged CEMP-r), and some are characterized by both s- and r-process enrichments (tagged CEMP-rs). The current distin…
Upflows in the Upper Solar Atmosphere
Tian, Hui; Brooks, David H.; Baker, Deborah +2 more
Spectroscopic observations at extreme- and far-ultraviolet wavelengths have revealed systematic upflows in the solar transition region and corona. These upflows are best seen in the network structures of the quiet Sun and coronal holes, boundaries of active regions, and dimming regions associated with coronal mass ejections. They have been intensi…
Constraints on the Assembly History of the Milky Way's Smooth, Diffuse Stellar Halo from the Metallicity-dependent, Radially Dominated Velocity Anisotropy Profiles Probed with K Giants and BHB Stars Using LAMOST, SDSS/SEGUE, and Gaia
Bird, Sarah A.; Zhao, Gang; Tian, Hai-Jun +5 more
We analyze the anisotropy profile of the Milky Way's smooth, diffuse stellar halo using the Sloan Digital Sky Survey (SDSS) SEGUE blue horizontal branch stars and the SDSS/SEGUE and LAMOST K giants. These intrinsically luminous stars allow us to probe the halo to approximately 100 kpc from the Galactic center. Line-of-sight velocities, distances, …
A new class of fossil fragments from the hierarchical assembly of the Galactic bulge
Dalessandro, E.; Saracino, S.; Valenti, E. +12 more
The formation and evolutionary processes of galaxy bulges are still unclear, and the presence of young stars in the bulge of the Milky Way is largely debated. We recently demonstrated that Terzan 5, in the Galactic bulge, is a complex stellar system hosting stars with very different ages and a striking chemical similarity to the field population. …