Search Publications
The XMM-Newton/HST View of the Obscuring Outflow in the Seyfert Galaxy Mrk 335 Observed at Extremely Low X-Ray Flux
Komossa, S.; Mathur, Smita; Krongold, Yair +8 more
The Seyfert galaxy Mrk 335 is known for its frequent changes of flux and spectral shape in the X-ray band that occurred during recent years. These variations may be explained by the onset of a wind that previous, noncontemporaneous high-resolution spectroscopy in X-ray and UV bands located at accretion disk scale. A simultaneous new campaign by XM…
The Physical Origins of the Identified and Still Missing Components of the Warm-Hot Intergalactic Medium: Insights from Deep Surveys in the Field of Blazar 1ES1553+113
Johnson, Sean D.; Drout, Maria R.; Chen, Hsiao-Wen +11 more
The relationship between galaxies and the state/chemical enrichment of the warm-hot intergalactic medium (WHIM) expected to dominate the baryon budget at low-z provides sensitive constraints on structure formation and galaxy evolution models. We present a deep redshift survey in the field of 1ES1553+113, a blazar with a unique combination of ultra…
Precise Ages of Field Stars from White Dwarf Companions
Tian, Haijun; Rix, Hans-Walter; Fouesneau, Morgan +2 more
Observational tests of stellar and Galactic chemical evolution call for the joint knowledge of a star’s physical parameters, detailed element abundances, and precise age. For cool main-sequence (MS) stars the abundances of many elements can be measured from spectroscopy, but ages are very hard to determine. The situation is different if the MS sta…
The Nature of Ionized Gas in the Milky Way Galactic Fountain
Zheng, Y.; Prochaska, J. X.; Deason, A. J. +6 more
We address the spatial scale, ionization structure, mass, and metal content of gas at the Milky Way disk-halo interface detected as absorption in the foreground of seven closely spaced, high-latitude halo blue horizontal branch stars with heights z = 3-14 kpc. We detect transitions that trace multiple ionization states (e.g., Ca II, Fe II, Si IV, …
Constraints on Upper Cutoffs in the Mass Functions of Young Star Clusters
Fall, S. Michael; Chandar, Rupali; Mok, Angus
We test claims that the power-law mass functions of young star clusters (ages ≲ few × 108 yr) have physical upper cutoffs at {M}* ∼ {10}5 {M}⊙ . Specifically, we perform maximum likelihood fits of the Schechter function, \psi (M)={dN}/{dM}\propto {M}β \exp (-M/{M}* ), to the observe…
The Transiting Multi-planet System HD15337: Two Nearly Equal-mass Planets Straddling the Radius Gap
Torres, Guillermo; Cochran, William D.; Endl, Michael +53 more
We report the discovery of a super-Earth and a sub-Neptune transiting the star HD 15337 (TOI-402, TIC 120896927), a bright (V = 9) K1 dwarf observed by the Transiting Exoplanet Survey Satellite (TESS) in Sectors 3 and 4. We combine the TESS photometry with archival High Accuracy Radial velocity Planet Searcher spectra to confirm the planetary natu…
Clues on the Origin and Evolution of Massive Contact Binaries: Atmosphere Analysis of VFTS 352
Sana, Hugues; Tramper, Frank; Justham, Stephen +10 more
The massive O4.5 V + O5.5 V binary VFTS 352 in the Tarantula Nebula is one of the shortest-period and most massive overcontact binaries known. Recent theoretical studies indicate that some of these systems could ultimately lead to the formation of gravitational waves via black hole binary mergers through the chemically homogeneous evolution pathwa…
Can the Superposition of Evaporative Flows Explain Broad Fe XXI Profiles during Solar Flares?
Polito, Vanessa; Testa, Paola; De Pontieu, Bart
The observation of the high-temperature (≳10 MK) Fe XXI 1354.1 Å line with the Interface Region Imaging Spectrograph has provided significant insights into the chromospheric evaporation process in flares. In particular, the line is often observed to be completely blueshifted, in contrast to previous observations at lower spatial and spectral resol…
Subarcsecond Blobs in Flare-related Coronal Jets
Zhang, Q. M.; Ni, L.
In this paper, we report multiwavelength observations of subarcsecond blobs in coronal jets. In AR 12149, a C5.5 circular-ribbon flare occurred at ∼04:55 UT on 2014 August 24, which consisted of a discrete circular ribbon and a short inner ribbon inside. Two jets (jet1 and jet2) were related to the flare. Jet1 appeared first and experienced untwis…
GROWTH on S190510g: DECam Observation Planning and Follow-up of a Distant Binary Neutron Star Merger Candidate
Duev, Dmitry A.; Kong, Albert K. H.; Cook, David O. +23 more
The first two months of the third Advanced LIGO and Virgo observing run (2019 April-May) showed that distant gravitational-wave (GW) events can now be readily detected. Three candidate mergers containing neutron stars (NS) were reported in a span of 15 days, all likely located more than 100 Mpc away. However, distant events such as the three new N…