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Stellar Populations and the Star Formation Histories of LSB Galaxies. V. WFC3 Color-Magnitude Diagrams
Schombert, James; McGaugh, Stacy
We present WFC3 observations of three low surface brightness (LSB) galaxies from the Schombert et al. LSB catalog that are within 11 Mpc of the Milky Way. Deep imaging at F336W, F555W, and F814W allow the construction of the V - I color-magnitude diagrams (CMD) to MI = -2. Overall 1869, 465, and 501 stellar sources are identified in the…
A Catalog of Point Sources Toward NGC 1333
Rebull, L. M.
I present a catalog of point-source objects toward NGC 1333, resolving a wide variety of confusion about source names (and occasionally positions) in the literature. I incorporate data from optical to radio wavelengths, but focus most of the effort on being complete and accurate from J (1.25 µm) to 24 µm. The catalog encompasses 52^\ci…
The Massive Star Population in M101. III. Spectra and Photometry of the Luminous and Variable Stars
Humphreys, Roberta M.; Grammer, Skyler H.; Gerke, Jill
We discuss moderate-resolution spectra, multicolor photometry, and light curves of 31 of the most luminous stars and variables in the giant spiral M101. The majority are intermediate A- to F-type supergiants. We present new photometry and light curves for three known “irregular blue variables,” V2, V4, and V9, and identify a new candidate. Their s…
Binary Astrometric Microlensing with Gaia
Sajadian, Sedighe
We investigate whether or not Gaia can specify the binary fractions of massive stellar populations in the Galactic disk through astrometric microlensing. Furthermore, we study whether or not some information about their mass distributions can be inferred via this method. In this regard, we simulate the binary astrometric microlensing events due to…
A Search for Intergalactic Globular Clusters in the Local Group
di Tullio Zinn, Graziella; Zinn, Robert
The whole Sloan Digital Sky Survey (SDSS, 14,555 {{deg }2}) has been searched for intergalactic globular clusters (IGCs) in the Local Group (LG). Using optical, infrared, and ultraviolet photometric selection criteria and photometric redshifts, the 2.1× {{10}8} objects in the SDSS Galaxy Catalog were reduced to only 183,791 b…
AGN Activity and IGM Heating in the Fossil Cluster RX J1416.4+2315
Raychaudhury, S.; Sengupta, C.; Khosroshahi, H. G. +3 more
We study active galactic nucleus (AGN) activity in the fossil galaxy cluster RX J1416.4+2315. Radio observations were carried out using the Giant Metrewave Radio Telescope at two frequencies, 1420 and 610 MHz. A weak radio lobe that extends from the central nucleus is detected in the 610 MHz map. Assuming the radio lobe originated from the central…
High Angular Resolution Multi-line Study of HH 1 and 2
Bally, J.; Raga, A. C.; Reipurth, Bo +2 more
We present new Hubble Space Telescope (HST) narrow band images of the bright Herbig-Haro (HH) objects HH 1 and 2 in the light of the Hα, Hβ, [O i] 6300, [O ii] 3726+28, [O iii] 5007 and [S ii] 6716+30 emission lines. The resulting emission and line ratio maps give an improved picture of the physical structure of these HH objects, showing the prese…
New Precision Orbits of Bright Double-Lined Spectroscopic Binaries. IX. HD 54371, HR 2692, and 16 Ursa Majoris
Williamson, Michael H.; Fekel, Francis C.; Muterspaugh, Matthew W. +3 more
With extensive sets of new radial velocities we have determined orbital elements for three previously known spectroscopic binaries, HD 54371, HR 2692, and 16 UMa. All three systems have had the lines of their secondaries detected for the first time. The orbital periods range from 16.24 to 113.23 days, and the three binaries have modestly or modera…
UrHip Proper Motion Catalog
Frouard, J.; Dorland, B. N.; Makarov, V. V. +2 more
Proper motions are computed and collected in a catalog using the Hipparcos positions (epoch 1991.25) and URAT1 positions (epoch 2012.3-2014.6). The goal is to obtain a significant improvement on the proper motion accuracy of single stars in the northern hemisphere, and to identify new astrometric binaries perturbed by orbital motion. For binaries …
A Calibration of NICMOS Camera 2 for Low Count Rates
Gladders, M. D.; Lidman, C.; Amanullah, R. +19 more
NICMOS 2 observations are crucial for constraining distances to most of the existing sample of z\gt 1 SNe Ia. Unlike conventional calibration programs, these observations involve long exposure times and low count rates. Reciprocity failure is known to exist in HgCdTe devices and a correction for this effect has already been implemented for high an…