3 edition of Persistent sub-yearly chromospheric variations in lower main-sequence stars found in the catalog.
Persistent sub-yearly chromospheric variations in lower main-sequence stars
by National Aeronautics and Space Administration, National Technical Information Service, distributor in [Washington, DC, Springfield, Va
Written in English
|Other titles||[Tau] Boö and α Com|
|Statement||Davesh Maulik, Robert A. Donahue, Sallie L. Baliunas.|
|Series||NASA contractor report -- NASA CR-204992..|
|Contributions||Donahue, Robert A., Baliunas, Sallie L., 1953-., United States. National Aeronautics and Space Administration.|
|The Physical Object|
The most massive stars appear in the center of the main sequence while less massive main sequence stars are brighter or dimmer than these stars as a consequence of their higher or lower temperatures. The more massive the star, the . Start studying astro. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Search. Higher mass main sequence stars have ____ temperature and ____ color, compared with lower mass main sequence stars. higher, bluer. Which of the following stars has the longest lifetime?
the main sequence (MS). From the location of a star in this diagram, one can estimate its age, mass, and radius. Stars with masses less than ;3 M J (with 1 M J 5 2 3 g 5 mass of the sun) are regarded as low-mass stars and have late spectral types, namely G, K, or M (2), equivalent to low surface temperatures of; to K. Such stars. In other words, a lower-gravity atmosphere, with its lower densities, must push the chromospheric inversion inward in mass column density to reach a depth where there are enough electrons to fuel the metal-ionization dominated cooling. Together with the other dependencies, the relation says that chromospheres become thicker in lower gravity Author: Thomas R. Ayres.
Chromospheric activity of periodic variable stars (including eclipsing binaries) observed in DR2 LAMOST stellar spectral survey spheric ﬂuxes and the amplitude of light curve variations on the rota-tion rates. Similarly, our main motivation is to build a large catalog of between and 70 days from , main-sequence Kepler targets. Start studying Astronomy CH 11 Practice Questions. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The relationship between mass and luminosity of stars on the main sequence is that. The radial-velocity curve of a star in a binary star system is a plot against time of. the variation of Doppler shift of.
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Persistent Sub-yearly Chromospheric Variations in Lower Main-Sequence Stars: r Bo5 and c_ Corn 1 Davesh Maulik 2,3 Robert A. Donahue 2'4 ([email protected]) Sallie L.
Baliunas 2'4,5 () Subject headings: stars: activity -- stars: planetary systems -- stars: late-type --techniques: photometric- techniques: spectroscopic. Persistent Sub-Yearly Chromospheric Variations in Lower Main-Sequence Stars: Tau Booe and alpha Com Article (PDF Available) July with 18 Reads How we measure 'reads'.
Persistent sub-yearly chromospheric variations in lower main-sequence stars: [Tau] Boö and [alpha] Com Author: Davesh Maulik ; Robert A Donahue ; Sallie L Baliunas ; United States. Persistent Sub-Yearly Chromospheric Variations in Lower Main-Sequence Stars: Tau Booe and alpha COM - NASA/ADS The recent discoveries of extrasolar planetary systems around lower main-sequence stars such as tau Booe (HD ) has prompted further investigation into their stellar by: 1.
As a persistent subyearly period in surface magnetic activity is unprecedented, we investigate this apparent anomaly further by examining chromospheric activity levels of other stars with similar mass, searching for variability in chromospheric activity with periods of less than one year, but longer than measured or predicted rotation.
Chromospheric variations in main-sequence stars. The fluxes in passbands nm wide and centered on the Ca II H and K emission cores have been monitored in stars of spectral type F2-M2 on. The fluxes in passbands nm wide and centered on the Ca II H and K emission cores have been monitored in stars of spectral type F2-M2 on or near the main sequence in a continuation of an observing program started by O.
Wilson. Most of the measurements began inwith observations scheduled monthly untilwhen observations were scheduled Cited by: Abstract: We explore the biological damage initiated in the environments of F, G, K, and M-type main-sequence stars due to photospheric, chromospheric and flare radiation.
The amount of chromospheric radiation is, in a statistical sense, directly coupled to the stellar age as well as the presence of significant stellar magnetic fields and dynamo activity. Chromospheric Variability in Early F-type Stars.
Chromospheric variations in main-sequence stars. For a sample of 47 lower main-sequence stars, including the. Using precise measurements of the helium D3 line, we have searched for statistically significant variations in the strength of chromospheric activity in 13 early F-type stars and two late F-type stars.
In two early F-type stars, we find short-term (hours to days) variability based on ~25 observations over the course of a week. In an additional two cases we find significant Cited by: 6.
We compile a chromospheric activity catalogue of cool stars from a combination of archival HARPS spectra and multiple other surveys, including the Mount Wilson data that have recently been released by the NSO.
We explore the variation in chromo-spheric activity of cool stars along the main sequence for stars with di erent e ective. Using published data on the Ca II K emission and rotation periods, correlations of these quantities with stellar parameters are analyzed in late main sequence stars (F8-K5).
The total power emission in the Ca II K line, L(k), is found to follow (1) an exponential decay, with the rotation period not dependent on the spectral type; (2) an.
Abstract. Variability studies of pre-main sequence (PMS) stars, which combine simultaneous data from different spectral regions, provide a powerful tool for investigating both the inhomogeneous outer atmospheric structure of these stars and the mechanisms causing their observed : Alexander Brown.
Spectroscopy of low mass pre-main sequence stars: photospheric spots and chromospheric activity M. Fernandez 1 and L.F. Miranda2 1 Max-Planck-Institut fur Astronomie, K¨onigst D Heidelberg, Germany ([email protected]) 2 Instituto de Astrof sica de Andaluc a, CSIC, Ap.
CorreosC/ Sancho Panza s/n, E Granada, Spain. Book Review: Cool stars, stellar systems and the sun / Astronomical Society of the Pacific, Persistent Sub-Yearly Chromospheric Variations in Lower Main-Sequence Stars.
Scale and time dependence of serial correlations in word-length time series of written texts Persistent Sub-Yearly Chromospheric Variations in Lower Main-Sequence Stars: Tau Booe and alpha Com. Rotational periods and evolutionary models for subgiant stars observed by CoRoT.
Jose-Dias do Nascimento Jr., Je´ erson Soares da Costa and Matthieu Castro Depart. de F´ısica Te orica e Experimental, Univ.
Federal do Rio Grande do Norte, CEP: Natal, RN, Brazil´ e-mail: [email protected] Preprint online version: Aug Cited by: 9. Abstract. The variability of solar radiation is a key factor influencing the terrestrial climate.
In the last few decades space-borne measurements of solar irradiance have revealed evidence of a correlation with the 11 yr solar activity cycle, although the amplitude of these changes is too small to produce significant climate variation through direct : M.
Vázquez. We also find that the pre-main-sequence stars GlGJ and Gl have a ratio lower than main-sequence single dM1e stars. These differences imply that different chromospheric structures are present on different stars, notably the temperature minimum must decrease with an increasing Hα/CaII EW ratio.
We analyze the X-ray emission and chromospheric activity of late-type F, G, and K stars studied in the framework of the HK project. More powerful coronas are possessed by stars displaying irregular variations of their chromospheric emission, while stars with cyclic activity are characterized by comparatively modest X-ray luminosities and ratios of the X-ray to Cited by:.
A few additional contributions are included from authors who for various reasons were unable to attend the meeting. Four years have passed since the last major international conference on chemically peculiar stars of the upper main sequence was held in Liege. Belgium in Previous conferences were held in (Vienna.The LAMOST spectral survey provides a rich databases for studying stellar spectroscopic properties and chromospheric activity.
We cross-matched a total ofperiodic variable stars from several photometric surveys and databases (CSS, LINEAR, Kepler, a recently updated eclipsing star catalogue, ASAS, NSVS, some part of SuperWASP survey, variable stars from Cited by: 5.The advent of Gaia parallaxes will allow many solar-type main sequence stars to be placed more accurately onto evolutionary isochrones, which will clarify the behavior of solar-mass stars in the latter parts of their main sequence lifetimes (unfortunately, this will not work for lower mass stars because of their very long evolutionary timescales).Author: Gibor Basri.