Search Publications
The Cepheid Distance to the Seyfert 1 Galaxy NGC 4151
Ferrarese, L.; Vestergaard, M.; Peterson, B. M. +15 more
We derive a distance of 15.8 ± 0.4 Mpc to the archetypal Seyfert 1 galaxy NGC 4151 based on the near-infrared Cepheid period-luminosity relation and new Hubble Space Telescope multiband imaging. This distance determination, based on measurements of 35 long-period (P > 25 days) Cepheids, will support the absolute calibration of the supermassive …
Properties of M Dwarf Flares at Millimeter Wavelengths
Hughes, A. Meredith; Osten, Rachel A.; MacGregor, A. Meredith
We report on two millimeter flares detected by the Atacama Large Millimeter/submillimeter Array at 220 GHz from AU Mic, a nearby M dwarf. The larger flare had a duration of only ∼35 s, with peak LR = 2 × 1015 erg s-1 Hz-1, and lower limit on linear polarization of | Q/I| > 0.12 ± 0.04. We examine the …
Resolving the FU Orionis System with ALMA: Interacting Twin Disks?
Liu, Hauyu Baobab; Williams, Jonathan; Zhu, Zhaohuan +7 more
FU Orionis objects are low-mass pre-main sequence stars characterized by dramatic outbursts several magnitudes in brightness. These outbursts are linked to episodic accretion events in which stars gain a significant portion of their mass. The physical processes behind these accretion events are not yet well understood. The archetypal FU Ori system…
Multiwavelength Follow-up of the Hyperluminous Intermediate-mass Black Hole Candidate 3XMM J215022.4-055108
Romanowsky, Aaron J.; Remillard, Ronald A.; Strader, Jay +6 more
We recently discovered the X-ray/optical outbursting source 3XMM J215022.4-055108. It was best explained as the tidal disruption of a star by an intermediate-mass black hole of mass of a few tens of thousand solar masses in a massive star cluster at the outskirts of a large barred lenticular galaxy at DL = 247 Mpc. However, we could not…
Exploring the Stellar Age Distribution of the Milky Way Bulge Using APOGEE
Cohen, Roger E.; Cunha, Katia; Smith, Verne V. +20 more
We present stellar age distributions of the Milky Way bulge region using ages for ∼6000 high-luminosity ( $\mathrm{log}(g)\lt 2.0$ ), metal-rich ([Fe/H] ≥ -0.5) bulge stars observed by the Apache Point Observatory Galactic Evolution Experiment. Ages are derived using The Cannon label-transfer method, trained on a sample of nearby luminous giants w…
Expanding the Y Dwarf Census with Spitzer Follow-up of the Coldest CatWISE Solar Neighborhood Discoveries
Meisner, Aaron M.; Cushing, Michael C.; Kirkpatrick, J. Davy +11 more
We present Spitzer 3.6 and 4.5 µm follow-up of 170 candidate extremely cool brown dwarfs newly discovered via the combination of Wide-field Infrared Survey Explorer (WISE) and NEOWISE imaging at 3-5 µm. CatWISE, a joint analysis of archival WISE and NEOWISE data, has improved upon the motion measurements of AllWISE by leveraging a >…
Magnetic Flux of Active Regions Determining the Eruptive Character of Large Solar Flares
Veronig, Astrid M.; Hou, Yijun; Li, Ting +3 more
We establish the largest eruptive/confined flare database to date and analyze 322 flares of Geostationary Operational Environmental Satellite class M1.0 and larger that occurred during 2010-2019, i.e., almost spanning all of solar cycle 24. We find that the total unsigned magnetic flux ( ${{\rm{\Phi }}}_{\mathrm{AR}}$ ) of active regions (ARs) is …
A Helium-flash-induced Mixing Event Can Explain the Lithium Abundances of Red Clump Stars
Schwab, Josiah
Observations demonstrate that the surface abundance of ${}^{7}\mathrm{Li}$ in low-mass stars changes dramatically between the tip of the red giant branch and the red clump. This naturally suggests an association with the helium core flash, which occurs between these two stages. Using stellar evolution models and a simple, ad hoc mixing prescriptio…
Magnetic Field Dependence of Bipolar Magnetic Region Tilts on the Sun: Indication of Tilt Quenching
Banerjee, Dipankar; Jha, Bibhuti Kumar; Karak, Bidya Binay +1 more
The tilt of the bipolar magnetic region (BMR) is crucial in the Babcock-Leighton process for the generation of the poloidal magnetic field in the Sun. Based on the thin flux-tube model of the BMR formation, the tilt is believed to be caused by the Coriolis force acting on the rising flux tube of the strong toroidal magnetic field from the base of …
Mapping the Galactic Disk with the LAMOST and Gaia Red Clump Sample. VI. Evidence for the Long-lived Nonsteady Warp of Nongravitational Scenarios
Wang, H. -F.; López-Corredoira, M.; Huang, Y. +6 more
By combining LAMOST DR4 and Gaia DR2 common red clump stars with age and proper motion, we analyze the amplitude evolution of the stellar warp independently of any assumption with a simple model. The greatest height of the warp disk increases with galactocentric distance in different populations and is dependent on age: the younger stellar populat…