Search Publications
Estimating the Ages of Open Star Clusters from Properties of Their Extended Tidal Tails
Kroupa, Pavel; Jeřábková, Tereza; Šubr, Ladislav +1 more
The most accurate current methods for determining the ages of open star clusters, stellar associations, and stellar streams are based on isochrone fitting or the lithium depletion boundary. We propose another method for dating these objects based on the morphology of their extended tidal tails, which have been recently discovered around several op…
Mid- and Far-infrared Color-Color Relations within Local Galaxies
Calzetti, Daniela; Heyer, Mark; Gregg, Benjamin
We present an extensive archival analysis of a sample of local galaxies, combining multiwavelength data from GALEX, Spitzer, and Herschel to investigate "blue-side" mid-infrared (MIR) and "red-side" far-infrared (FIR) color-color correlations within the observed infrared spectral energy distributions. Our sample largely consists of the KINGFISH ga…
Molecular and Atomic Clouds Associated with the Gamma-Ray Supernova Remnant Puppis A
Rowell, G.; Fukui, Y.; Reynoso, E. M. +3 more
We have carried out a study of the interstellar medium (ISM) toward the shell-like supernova remnant (SNR) Puppis A using NANTEN CO and ATCA H I data. We synthesized a comprehensive picture of the SNR radiation by combining the ISM data with the gamma-ray and X-ray distributions. The ISM, both atomic and molecular gas, is dense and highly clumpy, …
Hubble Space Telescope Observations of Active Asteroid P/2020 O1 (Lemmon-PANSTARRS)
Mutchler, Max; Jewitt, David; Agarwal, Jessica +3 more
We present Hubble Space Telescope observations of active asteroid P/2020 O1 taken to examine its development for a year after perihelion. We find that the mass loss peaks at ≲1 kg s-1 in 2020 August and then declines to nearly zero over four months. Long-duration mass loss (~180 days) is consistent with a sublimation origin, indicating …
Chemical Properties of the Local Disk and Halo. II. Abundances of 3745 M Dwarfs and Subdwarfs from Improved Model Fitting of Low-resolution Spectra
Nordlander, Thomas; Lépine, Sébastien; Hejazi, Neda
We present a model-fit pipeline to determine the stellar parameters of M-type dwarfs, which is an improvement on our previous work described in Hejazi et al. We apply this pipeline to analyze the low-resolution (R ~ 2000) spectra of 3745 M dwarfs/subdwarfs, collected at the MDM Observatory, Lick Observatory, Kitt Peak National Observatory, and Cer…
Solar Toroidal Field Evolution Spanning Four Sunspot Cycles Seen by the Wilcox Solar Observatory, the Solar and Heliospheric Observatory/Michelson Doppler Imager, and the Solar Dynamics Observatory/Helioseismic and Magnetic Imager
Scherrer, Philip H.; Liu, Allison L.
Forty-four years of Wilcox Solar Observatory, 14 years of Michelson Doppler Imager on the Solar and Heliospheric Observatory, and 11 years of Helioseismic and Magnetic Imager on the Solar Dynamics Observatory magnetic field data have been studied to determine the east-west inclination-the toroidal component-of the magnetic field. Maps of the zonal…
UV Counterpart of an X-Ray Ultrafast Outflow in IRAS 17020+4544
Kriss, Gerard A.; Mehdipour, Missagh; Nicastro, Fabrizio +7 more
We report on the discovery of a UV absorption counterpart of a low-ionization X-ray ultrafast outflow (UFO) in the narrow-line Seyfert 1 galaxy IRAS 17020+4544. This UV signature of the UFO is seen as a narrow and blueshifted Lyα absorption feature in the far-UV spectrum, taken with the Cosmic Origins Spectrograph (COS) on the Hubble Space Telesco…
TIC 114936199: A Quadruple Star System with a 12 Day Outer-orbit Eclipse
Kostov, Veselin B.; Powell, Brian P.; Rappaport, Saul A. +19 more
We report the discovery with TESS of a remarkable quadruple star system with a 2+1+1 configuration. The two unique characteristics of this system are that (i) the inner eclipsing binary (stars Aa and Ab) eclipses the star in the outermost orbit (star C), and (ii) these outer fourth-body eclipses last for ~12 days, the longest of any such system kn…
Measuring the α-abundance of Subsolar-metallicity Stars in the Milky Way's Central Half-parsec: Testing Globular Cluster and Dwarf Galaxy Infall Scenarios
Bentley, Rory O.; Kerzendorf, Wolfgang; Do, Tuan +4 more
While the Milky Way nuclear star cluster (MW NSC) has been studied extensively, how it formed is uncertain. Studies have shown it contains a solar and supersolar metallicity population that may have formed in situ, along with a subsolar-metallicity population that may have formed via mergers of globular clusters and dwarf galaxies. Stellar abundan…
Magnetic Helicity Evolution and Eruptive Activity in NOAA Active Region 11158
Pariat, E.; Green, L. M.; Valori, G. +3 more
Coronal mass ejections are among the Sun's most energetic activity events yet the physical mechanisms that lead to their occurrence are not yet fully understood. They can drive major space weather impacts at Earth, so knowing why and when these ejections will occur is required for accurate space weather forecasts. In this study we use a 4 day time…