Search Publications
The Exotic Eclipsing Nucleus of the Ring Planetary Nebula SuWt 2
Bond, Howard E.; Stassun, Keivan G.; Maxted, P. F. L. +3 more
SuWt 2 is a planetary nebula (PN) consisting of a bright ionized thin ring seen nearly edge-on, with much fainter bipolar lobes extending perpendicularly to the ring. It has a bright (12th magnitude) central star, too cool to ionize the PN, which we discovered in the early 1990s to be an eclipsing binary. Although it was anticipated that there wou…
Migration of a Moonlet in a Ring of Solid Particles: Theory and Application to Saturn's Propellers
Charnoz, Sébastien; Crida, Aurélien; Salmon, Julien +2 more
Hundred-meter-sized objects have been identified by the Cassini spacecraft in Saturn's A ring through the so-called propeller features they create in the ring. These moonlets should migrate due to their gravitational interaction with the ring; in fact, some orbital variations have been detected. The standard theory of type I migration of planets i…
Toward the General Red Giant Branch Slope-Metallicity-Age Calibration. I. Metallicities, Ages, and Kinematics for Eight Large Magellanic Cloud Clusters
Geisler, D.; Sharma, Saurabh; Borissova, J. +2 more
In this paper, we discuss the properties of color-magnitude diagrams, age, metallicity, and radial velocities of eight massive Large Magellanic Cloud (LMC) clusters using data taken from the FORS2 multiobject spectrograph at the 8.2 m Very Large Telescope/Unit Telescope 1. The strong near-infrared Ca II triplet lines of red giant branch stars obta…
The Discovery of Infrared Rings in the Planetary Nebula NGC 1514 During the WISE All-sky Survey
Hoard, D. W.; Wright, Edward L.; Wachter, Stefanie +3 more
We report the discovery of a pair of infrared, axisymmetric rings in the planetary nebula NGC 1514 during the course of the WISE all-sky mid-infrared survey. Similar structures are seen at visible wavelengths in objects such as the "Engraved Hourglass Nebula" (MyCn 18) and the "Southern Crab Nebula" (Hen 2-104). However, in NGC 1514 we see only a …
The Araucaria Project. Population Effects on the V- and I-band Magnitudes of Red Clump Stars
Udalski, Andrzej; Gieren, Wolfgang; Pietrzyński, Grzegorz +3 more
We present measurements of the V- and I-band magnitudes of red clump stars in 15 nearby galaxies obtained from recently published homogeneous Hubble Space Telescope photometry. Supplementing these results with similar data for another eight galaxies available in the literature, the populational effects on the V- and I-band magnitudes of red clump …
Mid-cycle Changes in Eta Carinae
Humphreys, Roberta M.; Davidson, Kris; Mehner, Andrea +1 more
In late 2006, ground-based photometry of η Car plus the Homunculus showed an unexpected decrease in its integrated apparent brightness, an apparent reversal of its long-term brightening. Subsequent Hubble Space Telescope (HST)/WFPC2 photometry of the central star in the near-UV showed that this was not a simple reversal. This multi-wavelength phot…
Occultation Observations of Saturn's B Ring and Cassini Division
French, Richard G.; Marouf, Essam A.; McGhee, Colleen A. +1 more
The outer edge of Saturn's B ring is strongly affected by the nearby 2:1 inner Lindblad resonance of Mimas and is distorted approximately into a centered elliptical shape, which at the time of the Voyager 1 and 2 encounters was oriented with its periapse toward Mimas. Subsequent observations have shown that the actual situation is considerably mor…
Mapping the Recent Star Formation History of the Disk of M51
Scowen, Paul A.; Kaleida, Catherine
Using data acquired as part of a unique Hubble Heritage imaging program of broadband colors of the interacting spiral system M51/NGC 5195, we have conducted a photometric study of the stellar associations across the entire disk of the galaxy in order to assess trends in size, luminosity, and local environment associated with the recent star format…
Lenticular Galaxies at the Outskirts of the Leo II Group: NGC 3599 and NGC 3626
Moiseev, A. V.; Sil'chenko, O. K.; Shulga, A. P.
We have studied unbarred S0 galaxies, NGC 3599 and NGC 3626, the members of the X-ray bright group Leo II, by means of three-dimensional spectroscopy, long-slit spectroscopy, and imaging, with the aim of identifying the epoch and mechanisms of their transformation from spirals. Both galaxies have appeared to bear complex features obviously resulti…
Star Cluster Candidates in M81
Brodie, Jean P.; Nantais, Julie B.; Huchra, John P. +2 more
We present a catalog of extended objects in the vicinity of M81 based on a set of 24 Hubble Space Telescope Advanced Camera for Surveys Wide Field Camera F814W (I-band) images. We have found 233 good globular cluster (GC) candidates; 92 candidate H II regions, OB associations, or diffuse open clusters; 489 probable background galaxies; and 1719 un…