McMath Telescope Research Articles

Recent observations of high-degree solar p-mode oscillations at the Kitt Peak National Observatory

Abstract. A brief summary is given of a program which is currently being carried out with the McMath telescope of the Kitt Peak National Observatory in order to study high-degree (l ≳ 150) solar p-mode oscillations. This program uses a 244 × 248 pixel CID camera and the main spectrograph of the McMath telescope to obtain velocity-time maps of the oscillations which can be converted into two-dimensional (k h - ω)) power spectra of the oscillations. Several different regions of the solar spectrum have been used in order to study the oscillations at different elevations in the solar atmosphere. The program concentrates on eastward- and westward-propagating sectoral harmonic waves so that measurements can be made of the absolute rotational velocities of the solar photospheric and shallow sub-photo spheric layers. Some preliminary results from this program are now available. First, we have been unable to confirm the existence of a radial gradient in the equatorial rotational velocity as was previously suggested. Second, we have indeed been able to confirm the presence of p-mode waves in the solar chromosphere as was first suggested by Rhodes et al. (1977). Third, we have been able to demonstrate differences in photospheric and chrornospheric power spectra.

Temporal autocorrelation functions of solar speckle pattern

A study of day-time temporal autocorrelation functions of speckles was performed on the solar granulation with the McMath telescope of the Kitt Peak National Observatory. In the space of only a few minutes, rapid variations of time constants are observed. For some observations, a single and high value T of time-constant is obtained: average = 170 ms, standard deviation = 80 ms. The temporal autocorrelation functions are consistent with theoretical curves obtained from a single layer atmospheric turbulence model. For other observations, a super-imposed short time-constant τ, showing little variations around 5.5 ms (standard deviation 1 ms), is also present. It is shown that T depends on the diameter of the telescope D and that the value τ of the short time scale, when it occurs, is correlated with the Fried parameter r 0.

Fourier Transform Spectrometer observations of solar carbon monoxide. I - The fundamental and first overtone bands in the quiet sun

Measurements of the 2200/cm fundamental and 4300/cm first overtone vibration-rotation band systems of solar carbon monoxide, were obtained with the Fourier Transform Spectrometer of the McMath telescope at Kitt Peak. The overtone measurements were taken at the east, north, and west heliocentric limbs, and at disk center. Observations of the strong fundamental bands were obtained at disk center and near the north limb. The low core brightness temperatures of the strongest fundamental carbon monoxide lines near the limb, reported previously by Noyes (1972) and Hall (1974), are confirmed. The possibility that thermal inhomogeneities might be responsible for the unusual behavior of the fundamental carbon dioxide lines have been examined. The somewhat discordant behavior of the fundamental lines at disk center compared with the north limb seems to favor a limb shadowing effect. The first overtone limb equivalent widths and the best-fit thermal and microvelocity models indicate a solar carbon abundance of 0.004 (on the scale with A sub H = 1) for an oxygen-to-carbon abundance ratio of 2.

Stellar model chromospheres. XI - A survey of CA II lambda 8542 line profiles in late-type stars of differing chromospheric activity

We have obtained profiles of the Ca II infrared triplet line λ8542 in 49 stars of spectral type F9-K3. These data were obtained with a silicon diode vidicon detector system on the KPNO McMath telescope and have a spectral resolution of 0.14 Å. We find no evidence for distinct emission features in the λ8542 lines, even for the most active chromosphere stars, but instead find that the line cores are filled in for active chromosphere stars compared to quiet chromosphere stars of the same spectral type. We derive chromospheric radiative loss rates in the A8542 line and find good correlations with chromospheric radiative loss rates in the Ca II H and K lines and Mg II h and k lines and with the Wilson-Bappu K-line index. Thus the λ8542 line is a good diagnostic of chromospheric activity. Computed λ8542 line profiles for the seven stars for which model chromospheres are available are not in as good agreement with the data as we would like, and for the three modeled giants the addition of macroturbulence cannot account for discrepancies in the line cores. We account for variability in the α Aur line profile as due to orbital motions of α Aur B, and we point out circumstellar features, indicating both outflowing and inflowing material, in six supergiants.

Evidence for long-period global oscillations of the Sun

THE results of our observations of the solar potassium resonance absorption line at 7,699 A using integrated solar light from the McMath telescope at Kitt Peak together with an atomic beam resonance scattering apparatus are reported here. In two long runs on successive days we observed wavelength oscillations of large amplitude with a period close to 160 min. If, as we believe, these oscillations are produced by motions of the photosphere, they provide evidence for oscillations of the entire Sun. We describe our experimental method, the analysis of the observations, and the results we obtain, and compare these with previous results.

Photospheric network from study of manganese lines

Area scans with the multi-channel magnetograph at the Kitt Peak McMath Telescope provided simultaneous measures of equivalent widths in two Mn lines, continuum intensity and longitudinal magnetic field component. Observations were carried out with apertures of 2.5″ × 3.5″ arc and 1″ × 1″ arc. For the network elements, which were identified using the magnetic field as tracer, we developed relationships betweenI Continuum,W λ V Doppler and longitudinal field strength. With a minimum of assumptions it is possible to write from these observed relations an expression connecting true temperature perturbation in the line forming layers of the network to true longitudinal field strength. The results provide some constraints upon possible network models.

Slow scan SEC vidicon system

A slow scan SEC vidicon system is described here. This system is coupled to the 152.4-cm (60-in) McMath telescope at Kitt Peak National Observatory. An anamorphic lens system is used to couple optically the vertical spectrograph to the vidicon system. The resolution of the over-all system is 55 mA, while the resolution of the spectrograph alone is 50 mA. mance.

Kitt Peak solar telescope to support Skylab project

Around the middle of July, solar astronomers at Kitt Peak National Observatory expect to be making the first observations with their new vacuum telescope. With its 60‐cm aperture and 33‐cm diameter solar image, the new instrument will be complementary to the much larger McMath telescope (150‐cm aperture, 80‐cm solar image) also at Kitt Peak; it will provide daily monitoring of the sun's magnetic activity on a routine basis not possible with the McMath telescope, which is normally used for individual research projects by KPNO staff members and visiting astronomers.