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Cold quasar investigation: comparing star formation rates to black hole growth
Kirkpatrick, Allison; Coleman, Brandon; Mintz, Sasha
Cold quasars are a rare population of luminous, unobscured quasars associated with host galaxies that have a high star formation rate. We aimed to study the host galaxies of 64 of these cold quasars in order to probe how the supermassive black holes and host galaxies were co-evolving. We compiled data from the XMM-XXL survey and cross-matched with…
Possibilities of identifying members from Milky Way satellite galaxies using unsupervised machine learning algorithms
Sivarani, Thirupathi; Divakar, Devika K.; Doddamani, Vijayakumar H. +1 more
A detailed study of stellar populations in Milky Way (MW) satellite galaxies remains an observational challenge due to their faintness and fewer spectroscopically confirmed member stars. We use unsupervised machine learning methods to identify new members for nine nearby MW satellite galaxies using Gaia data release-3 (Gaia DR3) astrometry, the Da…
A Perfect Tidal Storm: HD 104067 Planetary Architecture Creating an Incandescent World
Kane, Stephen R.; Howard, Andrew W.; Fetherolf, Tara +5 more
The discovery of planetary systems beyond the solar system has revealed a diversity of architectures, most of which differ significantly from our system. The initial detection of an exoplanet is often followed by subsequent discoveries within the same system as observations continue, measurement precision is improved, or additional techniques are …
The Property of the Gaia Celestial Reference Frame 3 (Gaia-CRF3)
Liu, Guangyi; Guo, Sufen
With the release of Gaia DR3, evaluating the performance and consistency of its reference frame (Gaia-CRF3) with the International Celestial Reference Frame (ICRF3) has become a critical task. Gaia-CRF3 serves as the second non-rotating inertial reference frame in the optical wavelength for the implementation of the International Celestial Referen…
Searching for Hypercompact Star Clusters in the Milky Way Using LAMOST and Gaia
Niu, Zexi; Yuan, Haibo; Zhang, Huawei +2 more
During the early merger of the Milky Way, intermediate-mass black holes (BHs) in merged dwarf galaxies may have been ejected from the center of their host galaxies due to gravitational waves, carrying some central stars along. This process can lead to the formation of hypercompact star clusters, potentially hosting BHs in the mass range of 10…
Advanced classification of hot subdwarf binaries using artificial intelligence techniques and Gaia DR3 data
Álvarez, M. A.; Dafonte, C.; Manteiga, M. +11 more
Context. Hot subdwarf stars are compact blue evolved objects, burning helium in their cores surrounded by a tiny hydrogen envelope. In the Hertzsprung-Russell Diagram they are located by the blue end of the Horizontal Branch. Most models agree on a quite probable common envelope binary evolution scenario in the Red Giant phase. However, the curren…
GMF G214.5-1.8 as traced by CO: I - cloud-scale CO freeze-out as a result of a low cosmic-ray ionization rate
Higgins, R.; Sánchez-Monge, Á.; Suri, S. +6 more
We present an analysis of the outer Galaxy giant molecular filament (GMF) G214.5-1.8 (G214.5) using IRAM 30m data of 12CO, 13CO, and C18O. We find that the 12CO (1-0) and (2-1) derived excitation temperatures are near identical and are very low, with a median of 8.2 K, showing that the gas is extremely c…
Chemical compositions of semiregular variable red giants
Lambert, David L.; Pozhath, Ramya
A sample of warm, low-level semiregular variables chosen from the General Catalogue of Variable Stars is studied for their chemical compositions by analysing high-resolution optical spectra. The abundance ratios from Na/Fe to Eu/Fe displayed by these and previously analysed semiregular variables are quite similar to ratios displayed by normal red …
A Far-ultraviolet-detected Accretion Shock at the Star–Disk Boundary of FU Ori
Herczeg, Gregory J.; France, Kevin; Hillenbrand, Lynne A. +1 more
FU Ori objects are the most extreme eruptive young stars known. Their 4–5 mag photometric outbursts last for decades and are attributed to a factor of up to 10,000 increase in the stellar accretion rate. The nature of the accretion disk-to-star interface in FU Ori objects has remained a mystery for decades. To date, attempts to directly observe a …
SCExAO/CHARIS Spectroscopic Characterization of Cloudy L/T Transition Companion Brown Dwarf HIP 93398 B
Jensen-Clem, Rebecca; Salama, Maïssa; Lewis, Briley L. +10 more
Brown dwarfs with measured dynamical masses and spectra from direct imaging are benchmarks that anchor substellar atmosphere cooling and evolution models. We present Subaru SCExAO/CHARIS infrared spectroscopy of HIP 93398 B, a brown dwarf companion recently discovered by Y. Li et al. (2023), as part of an informed survey using the Hipparcos–Gaia C…