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The Second Earth Trojan 2020 XL5
Tholen, David J.; Hui, Man-To; Wiegert, Paul A. +1 more
The Earth Trojans are coorbitals librating around the Lagrange points L 4 or L 5 of the Sun-Earth system. Although many numerical studies suggest that they can maintain their dynamical status and be stable on timescales up to a few tens of thousands of years or even longer, they remain an elusive population. Thus far only one…
The Decline and Fall of the Youngest Planetary Nebula
Balick, Bruce; Guerrero, Martín A.; Ramos-Larios, Gerardo
The Stingray Nebula, a.k.a. Hen3-1357, appeared for the first time in 1990 when bright nebular lines and radio emission that had not been observed before were unexpectedly discovered. In the ensuing years, the nebula faded precipitously. We report changes in shape and large decreases in its nebular emission-line fluxes based on well-calibrated ima…
Machine Learning the Sixth Dimension: Stellar Radial Velocities from 5D Phase-space Correlations
Lisanti, Mariangela; Cohen, Timothy; Dropulic, Adriana +3 more
The Gaia satellite will observe the positions and velocities of over a billion Milky Way stars. In the early data releases, the majority of observed stars do not have complete 6D phase-space information. In this Letter, we demonstrate the ability to infer the missing line-of-sight velocities until more spectroscopic observations become available. …
Hubble Space Telescope Observations of the Old Pulsar PSR J0108-1431
Pavlov, George G.; Mignani, Roberto P.; Abramkin, Vadim +1 more
We present results of optical-UV observations of the 200 Myr old rotation-powered radio pulsar J0108-1431 with the Hubble Space Telescope. We found a putative candidate for the far-UV (FUV) pulsar counterpart, with the flux density fν = 9.0 ± 3.2 nJy at λ = 1528 Å. The pulsar was not detected, however, at longer wavelengths, with 3σ upp…
Detection of a Multiphase Intragroup Medium: Results from the COS-IGrM Survey
Heckman, Timothy; Tumlinson, Jason; Borthakur, Sanchayeeta +3 more
We present the results of the Cosmic Origins Spectrograph-Intragroup Medium (COS-IGrM) Survey that used the COS on the Hubble Space Telescope to observe a sample of 18 UV bright quasars, each probing the IGrM of a galaxy group. We detect Lyα, C II, N V, Si II, Si III, and O VI in multiple sightlines. The highest ionization species detected in our …
In the Trenches of the Solar-stellar Connection. IV. Solar Full-disk Scans of C II, Si IV, and Mg II by the Interface Region Imaging Spectrograph
Testa, Paola; De Pontieu, Bart; Ayres, Thomas
About once a month, the Interface Region Imaging Spectrograph conducts day-long raster scans of the full Sun in three ultraviolet spectral channels. These full-disk mosaics are valuable in the solar context, but provide a unique connection to the distant, unresolved stars. Here, 10 deep-exposure scans (4-8 s per slit step), collected during the pe…
In the Trenches of the Solar-Stellar Connection. III. The HST/COS Ecliptic-poles Stellar Survey (EclipSS)
Ayres, Thomas R.
The Ecliptic-poles Stellar Survey (EclipSS) collected far-ultraviolet (FUV: 1160-1420 Å) spectra of 49 nearby (d ≲ 100 pc) F3-K3 main-sequence stars, located at high ecliptic latitudes (north and south), using the Cosmic Origins Spectrograph of the Hubble Space Telescope. The ecliptic poles receive higher exposures from scanning missions like the …
A Hard Look at Relativistic Reverberation in MCG-5-23-16 and SWIFT J2127.4+5654: Testing the Lamppost Model
Miller, J. M.; Zoghbi, A.; Cackett, E.
X-ray reverberation mapping has emerged as a new tool to probe accretion in active galactic nuclei (AGN), providing a potentially powerful probe of accretion at the black hole scale. The lags, along with relativistic spectral signatures are often interpreted in light of the lamppost model. Focusing specifically on testing the prediction of the rel…
The Merger Dynamics of the Galaxy Cluster A1775: New Insights from Chandra and XMM-Newton for a Cluster Simultaneously Hosting a Wide-angle Tail and a Narrow-angle Tail Radio Source
Hu, Dan; Xu, Haiguang; Zhu, Zhenghao +13 more
We present a new study of the merger dynamics of A1775 by analyzing the high-quality Chandra and XMM-Newton archival data. We confirm/identify an arc-shaped edge (i.e., the head) at ∼48 kpc west of the X-ray peak, a split cold gas tail that extends eastward to ∼163 kpc, and a plume of spiral-like X-ray excess (within about 81-324 kpc northeast of …
Multiple Populations in Low-mass Globular Clusters: Palomar 13
Carballo-Bello, Julio A.; Li, Chengyuan; Cabrera-Lavers, Antonio +7 more
Since the discovery of chemically peculiar stars in globular clusters in the last century, the study of multiple populations has become increasingly important, given that chemical inhomogeneity is found in almost all globular clusters. Despite various proposed theories attempting to explain this phenomenon, fitting all the observational evidence i…