Search Publications
Distance to M31 with the Hubble Space Telescope and HIPPARCOS Red Clump Stars
Garnavich, P. M.; Stanek, K. Z.
Following the approach by Paczyński & Stanek, we compare the red clump stars with parallaxes known to better than 10% in the Hipparcos catalog with the red clump stars observed in three fields in M31 using the Hubble Space Telescope. There are ~600 and ~6300 such stars in the two data sets, respectively. The local red clump luminosity function…
The Age of Globular Clusters in Light of Hipparcos: Resolving the Age Problem?
Chaboyer, Brian; Demarque, P.; Kernan, Peter J. +1 more
We review five independent techniques that are used to set the distance scale to globular clusters, including subdwarf main-sequence fitting utilizing the recent Hipparcos parallax catalog. These data together all indicate that globular clusters are farther away than previously believed, implying a reduction in age estimates. We now adopt a best-f…
Galactocentric Distance with the Optical Gravitational Lensing Experiment and HIPPARCOS Red Clump Stars
Paczyński, Bohdan; Stanek, Krzysztof Z.
We compare red clump stars with parallaxes known to better than 10% in the Hipparcos catalog and corrected for interstellar extinction with the OGLE red clump stars in Baade's Window, also corrected for interstellar extinction. There are ~600 and ~10,000 such stars in the two data sets, respectively. We find empirically that the average I-band mag…
The Problem of HIPPARCOS Distances to Open Clusters. I. Constraints from Multicolor Main-Sequence Fitting
Pinsonneault, Marc H.; Stauffer, John; Soderblom, David R. +2 more
Parallax data from the Hipparcos mission allow the direct distance to open clusters to be compared with the distance inferred from main-sequence (MS) fitting. There are surprising differences between the two distance measurements, indicating either the need for changes in the cluster compositions or reddening, underlying problems with the techniqu…
Testing the White Dwarf Mass-Radius Relation with HIPPARCOS
Provencal, J. L.; Shipman, H. L.; Thejll, P. +1 more
We present the Hipparcos parallaxes and resulting radii for 10 white dwarfs in visual binaries or common proper-motion systems and 11 field white dwarfs. For bright stars, Hipparcos parallaxes have uncertainties approaching 1 mas and are thus considerably more accurate than earlier ground-based parallaxes. Overall, our results support the predicti…
A Protocometary Cloud around HR 4796A?
Telesco, C.; Malkan, M.; Fisher, R. S. +3 more
We report both ROSAT observations and ground-based 10.8 µm imaging of the wide binary HR 4796, which consists of a main-sequence A-type star with a large amount of circumstellar dust, HR 4796A, and, at a separation of 7.7", a pre-main-sequence M-type companion, HR 4796B. From the ROSAT data, we find that the X-ray emission is centered on HR …
Strömgren Photometry of Globular Clusters: The Distance and Age of M13, Evidence for Two Populations of Horizontal-Branch Stars
Grundahl, Frank; VandenBerg, Don A.; Andersen, Michael I.
We present deep CCD photometry of the globular cluster M13 (NGC 6205) in the Strömgren uvbyβ system and determine a foreground reddening of E(b-y)=0.015+/-0.01 mag. From a fit to the main sequence of metal-poor subdwarfs with Hipparcos parallaxes, we derive (m-M)0=14.38+/-0.10, which implies an age near 12 Gyr assuming [Fe/H] = -1.61 an…
HIPPARCOS Parallaxes and the Cepheid Distance Scale
Madore, Barry F.; Freedman, Wendy L.
Hipparcos parallaxes have recently become available for a sample of Galactic Cepheids, and we have used these new distances to calibrate the Cepheid period-luminosity (PL) relation at six wavelengths (BVIJHK). Comparing these calibrations with previously published multiwavelength PL relations we find agreement to within 0.07 +/- 0.14 mag, or 4% +/…
Systematics of RR Lyrae Statistical Parallax. III. Apparent Magnitudes and Extinctions
Gould, Andrew; Popowski, Piotr
We sing the praises of the central limit theorem. Having previously removed all other possible causes of significant systematic error in the statistical-parallax determination of RR Lyrae absolute magnitudes, we investigate systematic errors from two final sources of input data: apparent magnitudes and extinctions. We find corrections due to each …
A ``Short'' Distance to the Large Magellanic Cloud With the Hipparcos Calibrated Red Clump Stars
Zaritsky, D.; Stanek, K. Z.; Harris, J.
Following an approach developed by Paczyński & Stanek, we derive a distance to the Large Magellanic Cloud (LMC) by comparing red clump stars from the Hipparcos catalog with the red clump stars observed in two fields in the LMC that were selected from the ongoing photometric survey of the Magellanic Clouds to lie in low-extinction regions. The …