We present Spitzer infrared imaging of the peculiar galaxy pair Arp 107 and compare with an optical Hα map and a numerical model of the interaction. The [3.6] - [4.5] colors of clumps in the galaxy do not vary around the ringlike primary spiral arm and are consistent with those of stars; thus, these bands are dominated by starlight. In contrast, the [5.8 μm] - [8.0 μm] colors are consistent with those of interstellar dust and vary by about 0.2 mag around the ring/spiral, with redder colors associated with regions with stronger star formation as indicated by Hα and mid-infrared luminosity. The [4.5 μm] - [5.8 μm] colors for clumps in this arm are bluer than dust and redder than stars and vary by 1.3 mag around the arm. This color is therefore a measure of the relative number of young stars to old stars, with a redder color indicating a higher proportion of young stars. There is a clear azimuthal sequence in the [4.5] - [5.8] color around the arm, indicating a sequence in average stellar age. The LHα/L8.0 μm ratio varies around the arm by a factor of ≈7; this variation may be due to extinction or to polycyclic aromatic hydrocarbon excitation by nonionizing photons. Our model of Arp 107 accounts for the general morphology of the system and explains the age variation along the arm as the result of differences in the time of maximum compression in the arm. Using Spitzer colors, we are able to distinguish background quasars and foreground stars from star-forming regions associated with Arp 107.

New spectroscopic observations of the double-lined chromospherically active binary 54 Camelopardalis (=AE Lyncis) have been obtained, resulting in improved orbital elements and the determination of the fundamental properties of the system. 54 Cam has a period of 11.06794 days, an eccentricity of 0.125, and a mass ratio of 0.9945. The spectral types are F8 IV-V and G5 IV, positioning the components on opposite sides of the Hertzsprung gap. From a comparison with theoretical evolutionary tracks, the masses are estimated to be 1.60 and 1.59 M. for the G and F stars, respectively, while the radii are 3.7 and 3.2 R.. Only the G star is chromospherically active. 54 Cam is particularly interesting since the F star is the brighter star at blue and red wavelengths, but the G star is slightly more massive and evolved. Both stars appear to be pseudosynchronously rotating, and the orbital and rotational inclinations are aligned. The lithium abundances of the two components are significantly different but consistent with standard theory, supporting the conclusion that both stars are more massive than the lithium-dip stars.

We present velocity observations, obtained with the E. W. Fick Observatory 0.6 m telescope, of the 7th magnitude K1 star HR 7112. Our observations show that HR 7112 is a double-line spectroscopic binary system composed of almost equal mass stars with a period of 215.6 days. The orbit has an eccentricity e = 0.142 and the stars orbit each other with a mean semi-major axis distance of approximately 0.4sin(i) AU. The masses of the stars are consistent with the classification as giant stars. Tidal effects are known to circularise the orbits of giant stars and this process is apparently underway in this system.

We report the discovery of a huge planetary nebula surrounding the ROSAT x-ray source RXJ 2117 + 34. The source corresponds to a star which is a member of the PG 1159 spectroscopic class, which are stars that have properties intermediate between planetary nebula nuclei (PNNs) and white dwarf stars. The nebula, which is detected through its [O III] and Halpha emission, has a maximum extent of 13 arcmin. This corresponds to a linear size of 5.3 pc at the published distance of 1.4 kpc. This size is five times greater than the largest previously known planetary nebula S68, which also surround a peculiar hot PG 1159-like PN central star. The expansion age of the RXJ nebula suggests that it is very old (approximately 1.5 X 10(5) yr), which is much older than its central star based on its position in the HR diagram. The morphology of the [O III] emission is interesting, showing a bipolar structure in its central parts and faint linear filaments, suggestive of shocks, in its outer regions. The discovery of an evolved PN around RXJ 2117 confirms that PG 1159 stars are transition objects between PNNs and helium-rich white dwarfs.

We have determined spectroscopic orbits for three chromospherically active giants that have hot compact companions. They are HD 160538 (K0 III+wd, P=904 days), HD 165141 (Gg III+wd, P approximately 5200 days), and HD 185510 (K0 III+sdB, P=20.6619 days). By fitting an IUE spectrum with theoretical models, we find the white dwarf companion of HD 165141 has a temperature of about 35 000 K. Spectral types and rotational velocities have been determined for the three giants and distances have been estimated. These three systems and 39 Ceti are compared with the barium star mass-transfer scenario. The long-period mild barium giant HD 165141 as well as HD 185510 and 39 Ceti, which have relatively short periods and normal abundance giants, appear to be consistent with this scenario, The last binary, HD 160538, a system with apparently near solar abundances, a white dwarf companion, and orbital characteristics similar to many barium stars, demonstrates that the existence of a white dwarf companion is insufficient to produce a barium star. The paucity of systems with confirmed white dwarf companions makes abundance analyses of HD 160538 and HD 165141 of great value in examining the role of metallicity in barium star formation.

6 Dra has long been known to show small variations in radial velocity, and there is photometric and spectroscopic evidence that its spectrum is composite. We show, largely on the basis of a generous number of photoelectric radial velocities mainly obtained at Cambridge and Fick observatories, that the orbit is of mild eccentricity and has a period of 562 days and a semi-amplitude of 7 km s−1.IUE observations show that the spectrum between 1600 and 1800 ∢ is consistent with its arising from a late-A main-sequence companion

Improved orbital elements have been determined for 39 Ceti and HD 185151.39 Cet has a circular orbit with an orbital period of 56.82 days, which differs substantially from its rotational period of 75-78 days. An observation of the lithium region of 39 Cet shows that the G5 III component has almost no lithium in its outer atmosphere. HD 185151 has a circular orbit with an orbital period of 40.142 days and has a nearly identical rotational period. The large mass function suggests that the secondary is a late A to mid F type star whose continuum should be visible at ultraviolet wavelengths. The orbital inclination is estimated to be 62 + or - 12, while the distance is about 390 pc. Orbital and rotational periods are compared for 114 chromospherically active binaries.

The authors show that 35 Com A (=HR 4894, HD 112033, the brightest component of ADS 8659) is a spectroscopic binary. It has a very eccentric orbit and a period of 8 years. There is no significance in the anomalously large mass that has sometimes been attributed to the system.

Three low-dispersion (15–50A/mm)−1 spectrum scanners have been developed at Fick Observatory as instrumentation for small telescope research and teaching activity. They have been applied in solar eclipse, zodiacal light, stellar, and comet research programs. The two plane grating spectrometers and one holographic grating instrument have been employed on telescopes ranging from 7.6 to 61 cm aperture, generally with f/5 to f/8 configurations. Recently, one of the plane grating instruments has been modified to perform as a four-channel spectrometer for quantitative spectral classification and composite spectra studies. This instrument is also being used to make spatial-spectral studies of the coma of Comet Halley, and other recent comets.

view Abstract Citations (157) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS E. W. Fick Observatory Stellar Radial Velocity Measurements. I. 1976--1984 Beavers, W. I. ; Eitter, J. J. Abstract Reported are approximately 16,000 stellar radial velocity measurements of nearly 2000 late-type stars obtained on 585 nights during the first eight years of operation of the E. W. Fick Observatory photoelectric radial velocity spectrometer at the 61 cm telescope coudé focus. Gradual improvements in the instrument during these years have reduced the observational error for high-quality dip objects to ±0.8 km s-1. The instrument velocity zero point agrees with that of the Lick survey. Comparisons with the zero points for other observatories are also given. Publication: The Astrophysical Journal Supplement Series Pub Date: September 1986 DOI: 10.1086/191136 Bibcode: 1986ApJS...62..147B Keywords: Astronomical Observatories; Radial Velocity; Stellar Motions; Astronomical Catalogs; High Dispersion Spectrographs; Late Stars; Tables (Data); Velocity Measurement; Astronomy; RADIAL VELOCITIES full text sources ADS | data products SIMBAD (1893)

The stellar radial velocity (RV) observations collected during the first eight years (1976–1984) of operation of the Fick Observatory photoelectric RV spectrometer have been tabulated for publication (Beavers and Eitter, 1986). Included are 16,000 observations of over 2,000 late-type stars. For these observations at the coudé focus of the 61 cm telescope the velocity zero-point is virtually the same as that for the early Lick radial velocity survey (Campbell and Moore, 1928), i.e. Lick-Fick = −0.08±0.08 km/sec. The zero-point comparison for DAO spectrometer measurements is DAO-Fick = −0.54±0.05 km/sec. During the last four years of this study the error of the “high quality dip” observations is ±0.8 km/sec. Thirty-three of these stars have been selected for use as future bright (m < 7.0) velocity standards at Fick Observatory.

Radial-velocity spectrometer measurements of both components of the double-line Capella system have been combined with earlier radial-velocity measurements from four previous studies to produce an improved double-line orbit. The resulting mass ratio M1/M2 = 1.18±0.02 differs by only 2% from the virtually ignored previous determination by W. Struve (1939). Combining the new radial-velocity elements with McAlister's (1981) recent interferometric orbit allows the determination of the individual masses of M1 = 3.31±0.08 M_sun; and M2 = 2.80±0.05 M_sun;. This mass difference is perhaps too great for both stars to be on the first crossing of the Hertzsprung gap as proposed by Boesgaard (1971).