Search Publications
The Spectrally Resolved Lyα Emission of Three Lyα-selected Field Galaxies at z ~ 2.4 from the HETDEX Pilot Survey
Finkelstein, Steven L.; Kollmeier, Juna A.; Blanc, Guillermo A. +11 more
We present new results on the spectrally resolved Lyα emission of three Lyα-emitting field galaxies at z ~ 2.4 with high Lyα equivalent width (>100 Å) and Lyα luminosity (~1043 erg s-1). At 120 km s-1 (FWHM) spectral resolution, the prominent double-peaked Lyα profile straddles the systemic velocity, where the v…
RX J1301.9+2747: A Highly Variable Seyfert Galaxy with Extremely Soft X-Ray Emission
Shu, Xinwen; Wang, Tinggui; Sun, Luming
In this paper we present a temporal and spectral analysis of X-ray data from XMM-Newton and Chandra observations of the ultrasoft and variable Seyfert galaxy RX J1301.9+2747. In both observations the source clearly displays two distinct states in the X-ray band: a long quiescent state and a short flare (or eruptive) state which differs in count ra…
An X-Ray and Multiwavelength Survey of Highly Radio-loud Quasars at z > 4: Jet-linked Emission in the Brightest Radio Beacons of the Early Universe
Brandt, W. N.; Schneider, Donald P.; Garmire, Gordon P. +3 more
We present a systematic study of the X-ray and multiwavelength properties of a sample of 17 highly radio-loud quasars (HRLQs) at z > 4 with sensitive X-ray coverage from new Chandra and archival Chandra, XMM-Newton, and Swift observations. Eight of the new and archival observations are reported in this work for the first time. New Chandra obser…
Late Spectral Evolution of the Ejecta and Reverse Shock in SN 1987A
Fransson, Claes; Kirshner, Robert P.; Leibundgut, Bruno +10 more
We present observations with the Very Large Telescope and Hubble Space Telescope (HST) of the broad emission lines from the inner ejecta and reverse shock of SN 1987A from 1999 February until 2012 January (days 4381-9100 after explosion). We detect broad lines from Hα, Hβ, Mg I], Na I, [O I], [Ca II], and a feature at ~9220 Å. We identify the latt…
ALMA Continuum Observations of a 30 Myr Old Gaseous Debris Disk around HD 21997
Apai, D.; Pascucci, I.; Ábrahám, P. +10 more
Circumstellar disks around stars older than 10 Myr are expected to be gas-poor. There are, however, two examples of old (30-40 Myr) debris-like disks containing a detectable amount of cold CO gas. Here we present Atacama Large Millimeter/Submillimeter Array (ALMA) and Herschel Space Observatory observations of one of these disks, around HD 21997, …
The Magnetic Systems Triggering the M6.6 Class Solar Flare in NOAA Active Region 11158
Toriumi, Shin; Kusano, Kanya; Inoue, Satoshi +3 more
We report a detailed event analysis of the M6.6 class flare in the active region (AR) NOAA 11158 on 2011 February 13. AR 11158, which consisted of two major emerging bipoles, showed prominent activity including one X- and several M-class flares. In order to investigate the magnetic structures related to the M6.6 event, particularly the formation p…
A Super-solar Metallicity for the Progenitor of Kepler's Supernova
Hughes, John P.; Lee, Jae-Joon; Mori, Koji +8 more
We have performed deep X-ray observations of the remnant of Kepler's supernova (SN 1604) as a Key Project of the Suzaku Observatory. Our main goal is to detect secondary Fe-peak elements in the supernova (SN) ejecta to gain insights into the Type Ia SN explosion mechanism and the nature of the progenitor. Here, we report our initial results. We ma…
Photometric Determination of the Mass Accretion Rates of Pre-main-sequence Stars. IV. Recent Star Formation in NGC 602
Panagia, Nino; Beccari, Giacomo; De Marchi, Guido
We have studied the young stellar populations in NGC 602, in the Small Magellanic Cloud, using a novel method that we have developed to combine Hubble Space Telescope photometry in the V, I, and Hα bands. We have identified about 300 pre-main-sequence (PMS) stars, all of which are still undergoing active mass accretion, and have determined their p…
Carbon Monoxide in the Cold Debris of Supernova 1987A
Blommaert, J. A. D. L.; van Loon, J. Th.; Fransson, C. +27 more
We report spectroscopic and imaging observations of rotational transitions of cold CO and SiO in the ejecta of SN1987A, the first such emission detected in a supernova remnant. In addition to line luminosities for the CO J = 1-0, 2-1, 6-5, and 7-6 transitions, we present upper limits for all other transitions up to J = 13-12, collectively measured…
Can the Differential Emission Measure Constrain the Timescale of Energy Deposition in the Corona?
Parenti, S.; Auchère, F.; Klimchuk, J. A. +2 more
In this paper, the ability of the Hinode/EIS instrument to detect radiative signatures of coronal heating is investigated. Recent observational studies of active region cores suggest that both the low and high frequency heating mechanisms are consistent with observations. Distinguishing between these possibilities is important for identifying the …