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An Analysis of the Shapes of Interstellar Extinction Curves. VIII. The Optical Extinction Structure
Gordon, Karl D.; Fitzpatrick, E. L.; Massa, Derck
New Hubble Space Telescope/STIS optical spectra were obtained for a sample of early-type stars with existing International Ultraviolet Explorer UV spectra. These data were used to construct optical extinction curves whose general properties are discussed elsewhere. In this paper, we identify extinction features in the curves that are wider than di…
On the Chemical and Kinematic Consistency between N-rich Metal-poor Field Stars and Enriched Populations in Globular Clusters
Shi, Jianrong; Fernández-Trincado, J. G.; Gao, Qi +5 more
Interesting chemically peculiar field stars may reflect their stellar evolution history and their possible origin in a different environment from where they are found now; this is one of the most important research fields in Galactic archeology. To explore this further, we have used the CN-CH bands around 4000 Å to identify N-rich metal-poor field…
Increasing Activity in T CrB Suggests Nova Eruption Is Impending
Sokoloski, J. L.; Mukai, Koji; Luna, Gerardo J. M. +1 more
Estimates of the accretion rate in symbiotic recurrent novae (RNe) often fall short of theoretical expectations by orders of magnitude. This apparent discrepancy can be resolved if the accumulation of mass by the white dwarf (WD) is highly sporadic, and most observations are performed during low states. Here we use a re-analysis of archival data f…
Calibrating Mg II-based Black Hole Mass Estimators Using Low-to-high-luminosity Active Galactic Nuclei
Xue, Yongquan; Woo, Jong-Hak; Le, Huynh Anh N.
We present single-epoch black hole mass (MBH) estimators based on the rest-frame ultraviolet (UV) Mg II 2798 Å and optical Hβ 4861 Å emission lines. To enlarge the luminosity range of active galactic nuclei (AGNs), we combine the 31 reverberation-mapped AGNs with relatively low luminosities from Bahk et al., 47 moderate-luminosity AGNs …
Discovery of Magellanic Stellar Debris in the H3 Survey
Conroy, Charlie; Ting, Yuan-Sen; Cargile, Phillip A. +9 more
We report the discovery of 15 stars in the H3 survey that lie, in projection, near the tip of the trailing gaseous Magellanic Stream (MS). The stars have Galactocentric velocities <-155 km s-1, Galactocentric distances of ≈40 to 80 kpc (increasing along the MS), and [Fe/H] consistent with that of stars in the Small Magellanic Cloud. …
Luminous Lyα Emitters with Very Blue UV-continuum Slopes at Redshift 5.7 ≤ z ≤ 6.6
Jiang, Linhua; Schaerer, Daniel; Egami, Eiichi +4 more
We study six luminous Lyα emitters (LAEs) with very blue rest-frame UV continua at 5.7 ≤ z ≤ 6.6. These LAEs have previous Hubble Space Telescope (HST) and Spitzer IRAC observations. Combining our newly acquired HST images, we find that their UV-continuum slopes β are in a range of -3.4 ≤ β ≤ -2.6. Unlike previous, tentative detections of β ≃ -3 i…
The R-Process Alliance: A Very Metal-poor, Extremely r-process-enhanced Star with [Eu/Fe] = + 2.2, and the Class of r-III Stars
Beers, Timothy C.; Placco, Vinicius M.; Hattori, Kohei +8 more
We report the discovery of J1521-3538, a bright (V = 12.2), very metal-poor ([Fe/H] = -2.8) strongly r-process-enhanced field horizontal branch star, based on a high-resolution, high signal-to-noise Magellan/MIKE spectrum. J1521-3538 shows the largest r-process element overabundance in any known r-process-enhanced star, with [Eu/Fe] = +2.2, and it…
The Accretion History of AGN: A Newly Defined Population of Cold Quasars
Kartaltepe, Jeyhan S.; Kirkpatrick, Allison; Marchesi, Stefano +15 more
Quasars are the most luminous of active galactic nuclei, and are perhaps responsible for quenching star formation in their hosts. The Stripe 82X catalog covers 31.3 deg2 of the Stripe 82 field, of which the 15.6 deg2 covered with XMM-Newton is also covered by Herschel/SPIRE. We have 2500 X-ray detected sources with multiwavel…
The Population of Galactic Planetary Nebulae: a Study of Distance Scales and Central Stars Based on the Second Gaia Release
Stanghellini, Letizia; Bucciarelli, Beatrice; Lattanzi, Mario G. +1 more
We matched the astrometry of central stars (CSs) of spectroscopically confirmed Galactic planetary nebulae (PNe) with DR2 Gaia parallaxes (p), finding 430 targets in common with p > 0 and $| {\sigma }_{{\rm{p}}}/p| \lt 1$ ∣ σ p / p ∣ < 1 . A catalog of PNe whose CSs have DR2 Gaia parallaxes is presented in Table 1. We compared DR2 parallaxes…
Hot Subdwarf Stars Identified in Gaia DR2 with Spectra of LAMOST DR6 and DR7. II.Kinematics
Luo, Yangping; Németh, Péter; Li, Qida
Combining LAMOST radial velocities with Gaia parallaxes and proper motions, we present 3D Galactic space motions and the orbits of 182 single-lined hot subdwarf stars. These stars were identified by Lei et al. in Gaia DR2 with LAMOST DR6 and DR7 spectra. He-rich hot subdwarf stars with $\mathrm{log}(y)\geqslant 0$ show the largest standard deviati…