Search Publications
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. …
The Single-cloud Star Formation Relation
Henning, Thomas; Myers, Philip C.; Gutermuth, Robert A. +10 more
One of the most important and well-established empirical results in astronomy is the Kennicutt-Schmidt relation between the density of interstellar gas and the rate at which that gas forms stars. A tight correlation between these quantities has long been measured at galactic scales. More recently, using surveys of YSOs, a KS relationship has been …
A scaling relationship for non-thermal radio emission from ordered magnetospheres: from the top of the main sequence to planets
Umana, G.; Fossati, L.; Loru, S. +20 more
In this paper, we present the analysis of incoherent non-thermal radio emission from a sample of hot magnetic stars, ranging from early-B to early-A spectral type. Spanning a wide range of stellar parameters and wind properties, these stars display a commonality in their radio emission which presents new challenges to the wind scenario as original…
GJ 367b: A dense, ultrashort-period sub-Earth planet transiting a nearby red dwarf star
Hellier, Coel; Latham, David W.; Quinn, Samuel N. +75 more
Ultrashort-period (USP) exoplanets have orbital periods shorter than 1 day. Precise masses and radii of USP exoplanets could provide constraints on their unknown formation and evolution processes. We report the detection and characterization of the USP planet GJ 367b using high-precision photometry and radial velocity observations. GJ 367b orbits …
Year 1 of the ZTF high-cadence Galactic plane survey: strategy, goals, and early results on new single-mode hot subdwarf B-star pulsators
Hermes, J. J.; Duev, Dmitry A.; Riddle, Reed +18 more
We present the goals, strategy, and first results of the high-cadence Galactic plane survey using the Zwicky Transient Facility (ZTF). The goal of the survey is to unveil the Galactic population of short-period variable stars, including short-period binaries, and stellar pulsators with periods less than a few hours. Between 2018 June and 2019 Janu…