Reddenings of Cepheids from G-band spectrophotometry

Milky Way Rotation from Cepheids

The 87 new 0 determinations were added to the existing sample of cepheids with known radial velocities, forming an extended sample of 278 galactic classical cepheids with reliable radial velocity and photometry. We then calculated distances for these objects through a Period-Luminosity-Colour relation due to Feast & Walker (1987). The position of the cepheids in the galactic disk as given by th...

Calibration of the Distance Scale from Cepheids

Are the Cepheids in Ic 4182 Different from Population I Cepheids in the Galaxy?

Recently, the Cepheids in the spiral galaxy IC 4182 have been in the spotlight due to their use as calibrators for th~ supern~va la d~sta~ce scale: In this process the distance to IC 4182 is obtained by applying the local PopulatIOn I perIod-lumInosity relatIOn to the IC 4182 Cepheid sample. But is it really appropriate to do so? W,e employ t~e technique of Fourier decomposition to compare the ...

Surface Composition of Mercury from Reflectance Spectrophotometry

Reflectance spectra of Mercury have been obtained periodically from 1963 through 1984. Since 1969, these observations were made in an effort to learn about the surface mineralogical composition of Mercury. Using the phases of the planet around maximum elongations, Mercury's 6Y3851day rotational rate, and the theory of bidirectional rejectance spectroscopy, some spatial resolution across the pla...

Determination of the Distance to M33 Based on Single Epoch I-band Hst Observations of Cepheids

We have determined the distance to M33 using single epoch I-band observations of Cepheids based on HST/WFPC2 images of five fields in M33. Combining the HST I-band photometry and the periods determined from the ground-based observations (DIRECT) for 21 Cepheids with logP > 0.8 in the sample of 32 Cepheids, we derive a distance modulus of (m−M)0 = 24.52±0.14(random)±0.13(systematic) for an adopt...