Search Publications
Supernova Remnant Progenitor Masses in M31
Dolphin, Andrew E.; Williams, Benjamin F.; Gilbert, Karoline M. +5 more
Using Hubble Space Telescope photometry, we age-date 59 supernova remnants (SNRs) in the spiral galaxy M31 and use these ages to estimate zero-age main-sequence masses (M ZAMS) for their progenitors. To accomplish this, we create color-magnitude diagrams (CMDs) and employ CMD fitting to measure the recent star formation history of the r…
COSMOS: Stochastic Bias from Measurements of Weak Lensing and Galaxy Clustering
Massey, Richard; Kneib, Jean-Paul; Rhodes, Jason +6 more
In the theory of structure formation, galaxies are biased tracers of the underlying matter density field. The statistical relation between galaxy and matter density field is commonly referred to as galaxy bias. In this paper, we test the linear bias model with weak-lensing and galaxy clustering measurements in the 2 deg2 COSMOS field. W…
It's Alive! The Supernova Impostor 1961V
Van Dyk, Schuyler D.; Matheson, Thomas
Reports of the death of the precursor of supernova (SN) 1961V in NGC 1058 are exaggerated. Consideration of the best astrometric data shows that the star, known as "Object 7," lies at the greatest proximity to SN 1961V and is the likely survivor of the "SN impostor" super-outburst. SN 1961V does not coincide with a neighboring radio source and is …
Physical Properties of the Narrow-line Region of Low-mass Active Galaxies
Ho, Luis C.; Barth, Aaron J.; Greene, Jenny E. +1 more
We present spectroscopic observations of 27 active galactic nuclei (AGNs) with some of the lowest black hole (BH) masses known. We use the high spectral resolution and small aperture of our Keck data, taken with the Echellette Spectrograph and Imager, to isolate the narrow-line regions (NLRs) of these low-mass BHs. We investigate their emission-li…
The Cluster of Blue Stars Surrounding the M31 Nuclear Black Hole
Green, Richard F.; Kormendy, John; Lauer, Tod R. +2 more
We obtained U 330- and B-band images of the M31 nucleus using the High Resolution Camera of the Advanced Camera for Surveys on board the Hubble Space Telescope (HST). The spatial resolution in the U 330 band, 0farcs03 FWHM, or 0.1 pc at M31, is sufficient to resolve the outskirts of the compact cluster (P3) of UV-bright stars…
AKARI Observations of Brown Dwarfs. III. CO, CO2, and CH4 Fundamental Bands and Physical Parameters
Yamamura, I.; Sorahana, S.
We investigate variations in the strengths of three molecular bands, CH4 at 3.3 µm, CO at 4.6 µm, and CO2 at 4.2 µm, in 16 brown dwarf spectra obtained by AKARI. Spectral features are examined along the sequence of source classes from L1 to T8. We find that the CH4 3.3 µm band is present in …
The Panchromatic Hubble Andromeda Treasury. I. Bright UV Stars in the Bulge of M31
Bell, Eric F.; Skillman, Evan D.; Williams, Benjamin F. +20 more
As part of the Panchromatic Hubble Andromeda Treasury multi-cycle program, we observed a 12' × 6farcm5 area of the bulge of M31 with the WFC3/UVIS filters F275W and F336W. From these data we have assembled a sample of ~4000 UV-bright, old stars, vastly larger than previously available. We use updated Padova stellar evolutionary tracks to classify …
Germanium, Arsenic, and Selenium Abundances in Metal-poor Stars
Roederer, Ian U.
The elements germanium (Ge, Z = 32), arsenic (As, Z = 33), and selenium (Se, Z = 34) span the transition from charged-particle or explosive synthesis of the iron-group elements to neutron-capture synthesis of heavier elements. Among these three elements, only the chemical evolution of germanium has been studied previously. Here we use archive obse…
From X-Ray Dips to Eclipse: Witnessing Disk Reformation in the Recurrent Nova U Sco
Talavera, A.; Ness, J. -U.; Hernanz, M. +9 more
The tenth recorded outburst of the recurrent eclipsing nova U Sco was observed simultaneously in X-ray, UV, and optical by XMM-Newton on days 22.9 and 34.9 after the outburst. Two full passages of the companion in front of the nova ejecta were observed, as was the reformation of the accretion disk. On day 22.9, we observed smooth eclipses in UV an…
Trajectories and Distribution of Interstellar Dust Grains in the Heliosphere
Slavin, Jonathan D.; Reach, William T.; Müller, Hans-Reinhard +4 more
The solar wind carves a bubble in the surrounding interstellar medium (ISM) known as the heliosphere. Charged interstellar dust grains (ISDG) encountering the heliosphere may be diverted around the heliopause or penetrate it depending on their charge-to-mass ratio. We present new calculations of trajectories of ISDG in the heliosphere, and the dus…