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Wednesday, May 13, 2020 | History

2 edition of The Mg II lines as diagnostic of PMS nature in Herbig Ae/Be stars found in the catalog.

The Mg II lines as diagnostic of PMS nature in Herbig Ae/Be stars

The Mg II lines as diagnostic of PMS nature in Herbig Ae/Be stars

final report : IUE Observing Program.

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Published by National Aeronautics and Space Administration, National Technical Information Service, distributor in [Washington, DC, Springfield, Va .
Written in English

    Subjects:
  • A stars.,
  • Absorption spectra.,
  • B stars.,
  • Cygnus constellation.,
  • Infrared signatures.,
  • Line spectra.,
  • Main sequence stars.,
  • Stellar envelopes.

  • Edition Notes

    Other titlesMg 2 lines as diagnostic of PMS nature in Herbig Ae/Be stars., IUE Observing Program.
    SeriesNASA contractor report -- NASA CR-197518.
    ContributionsUnited States. National Aeronautics and Space Administration.
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL15408562M

    Key words: stars: individual: V Cyg { stars: variables: T Tauri { stars: variables: Herbig Ae/Be { stars: winds, out ows. 1 INTRODUCTION T Tauri stars (TTS) are pre-main-sequence (PMS) objects of low masses (6 2 M of cTTS and their models, see e.g. Bouvier et . Milli-arcsecond images of the Herbig Ae star HD NASA Astrophysics Data System (ADS) Renard, S.; Malbet, F.; Benisty, M.; Thiébaut, E.; Berger, J.-P.

      Introduction. Embryonal tumors of the CNS are a heterogeneous group for which a precise diagnosis by morphological criteria is problematic. Most common among them is medulloblastoma, classically arising in the posterior fossa, probably from cerebellar granule cells (Pomeroy et al. ).Supratentorial primitive neuroectodermal tumor (SPNET) is a rarer, aggressive embryonal Cited by: UV VARIABILITY AND ACCRETION IN PMS STARS IN NGC Venuti, Bouvier, Irwin et al. 2S X-SHOOTER MONITORING OF THE ACCRETION RATE IN HERBIG AE/BE STARS: Mendigutía, Brittain, Mora et al. 2S INTERPRETING NEAR INFRARED HYDROGEN LINE RATIOS IN T TAURI STARS: Edwards, Kwan, Fischer et al. 2S

    I am 78 years old and wonder how likely my condition will become full-blown multiple myeloma. MGUS is far more common than myeloma. Only a small fraction of people (1 percent per year) progress to.   It seems reasonable to assume that the metallicity of the PMS stars in the Sh region is similar to the central B stars; however, if other processes lead to the metal-deficient nature of the central B stars, the PMS stars may have higher abundances. Future work on the Z determination of PMS stars in Sh would thus be by:


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The Mg II lines as diagnostic of PMS nature in Herbig Ae/Be stars Download PDF EPUB FB2

The MG 2 lines as diagnostic of PMS nature in Herbig Ae/Be stars Abstract The main objective of this program was to observe some newly discovered and previously unobserved Herbig Ae. We argue that the structure of the Mg II lines is a superior diagnostic of the dynamical activity and ultimately of the PMS nature of these objects.

This is a crucial test for the characterization of the HAB stars. The Mg II lines as diagnostic of PMS nature in Herbig Ae/Be stars: final report: IUE Observing Program.

The arguement, for the purposes of this proposal, that the structure of the Mg II lines was a superior diagnostic of the dynamical activity and ultimately the PMS nature of these objects. This program was a follow up study of several interesting intermediate-mass stars with the goal of classifying these objects based on the shape of their MG II lines.

High resolution IUE spectra, in the spectral region of the Mg II resonance lines of 16 A stars were obtained. To interpret these observations, the formation of Mg II lines in an A type stellar atmosphere for different values of Mg abundance and microturbulence within the framework of the NLTE theory with complete and partial redistribution of the Mg II line profiles were : R.

Freire-Ferrero, A. Talavera, P. Gouttebroze. Observations by IUE of the short-term variability of the Mg II and Ca II resonance lines in the Herbig Ae star HD are presented.

The Herbig Ae/Be stars (HAeBes) allow an exploration of the properties of Pre- Main Sequence(PMS) star s above the low-mass range (⊙) and those b ordering the high-mass range (> 8 M ⊙).

J.-C. Bouret & C. Catala: Multi-line analysis of the spectra of Herbig Ae/Be stars T able 3. The direction of the arrow indicates the sense of variation of the feature when the parameter is. The origin of the Br γ line in Herbig Ae/Be stars is still an open question.

It has been proposed that a fraction of the μm Br γ emission might emerge from a disc wind, the magnetosphere. Our data show that, if the stars rotate as solid bodies, low mass Herbig stars (Mangular momentum during their PMS evolution, which could be accounted.

Context. Observations of the Mg II h and k lines in solar prominences with IRIS reveal a wide range of line shapes from simple non-reversed profiles to typical double-peaked reversed profiles, and with many other possible complex line shapes.

The physical conditions responsible for this variety are not well understood. Aims: Our aim is to understand how physical conditions inside a prominence Cited by: 1.

The origin of magnetic fields in intermediate- and high-mass stars is fundamentally a mystery. Clues towards solving this basic astrophysical problem can likely be found at the pre-main-sequence (PMS) evolutionary stage.

With this work, we perform the largest and most sensitive search for magnetic fields in PMS Herbig Ae/Be (HAeBe) by:   INTRODUCTION.

Herbig was the first to perform a systematic study of a certain class of stars that we call now Herbig Ae/Be (HAeBe) stars, and whose observational parameters are as follows: the spectral type is A or earlier, with emission lines; the star lies in an obscured region of space; the star illuminates fairly bright nebulosity in its immediate by: Mg II h and k emission lines of the M2 giant beta Peg and the M5 supergiant alpha Her were detected in Copernicus observations.

In the alpha Her profiles, similar to alpha Ori and alpha Sco profiles, the k line is asymmetric and the h line is symmetric.

The possibility that the k line asymmetry is produced by overlying absorption is by: 3. B[e] stars have hydrogen line emission and forbidden [Fe 11] and [0 I] emission lines in their spectra; they are also characterized by a strong IR excess due to circumstellar dust.

Having a large amount of extinction in the UV and the visual they have been less frequently observed than other emission line. "The Mg II Lines as Diagnostic of PMS Nature in Herbig Ae/Be Stars" Goals.

The main objective of this program was to observe some newly discovered and previously unobserved Herbig Ae/Be (HAeBe) stars with lUE. A previous archival study suggested that there was a full range of profiles in the Mg II lines for these objects; ranging.

Finally, V Tau is a well-known Herbig Ae/Be type member of Taurus (Elias ) that also illuminates an optical reflection nebula—an original defining characteristic of the Herbig Ae/Be population. The two additional smaller IR nebulae are likewise associated with early-type or high-luminosity stars.

It can be used to summarize temporal spectral changes in PMS A-type stars, and to search for peculiar types. We have used this scheme to classify 38 Herbig Ae stars as well as 22 PMS stars in the young open clusters NGCNGCand IC We have also used this extended system to search for λ Boötis stars among PMS A-type stars.

As many group I sources are resolved at 25 μm, we suggest that many, but not all, group I Herbig Ae/Be disks have a hole or gap and are (pre-)transitional disks. On the other hand, the unresolved nature of many group II sources at 25 μm supports the idea that group II disks have a continuous flat disk geometry.

It has been inferred that group. Magnetism of Herbig Ae/Be stars. G.A. Wade, E. Alecian, J. Grunhut C. Catala S. Bagnulo, C.P. Folsom J.D. Landstreet Abstract.

Observations of magnetic fields of stars at the pre-main sequence phase can provide important new insights into the complex physics of the late stages of star formation.

This is especially true at intermediate stellar. The Mg 2 lines as diagnostic of PMS nature in Herbig Ae/Be stars by NON. texts. eye The main objective of this program was to observe some newly discovered and previously unobserved Herbig Ae/Be (HAeBe) stars with IUE.

A previous archival study suggested that there was a full range of profiles in the Mg II lines for these objects. Outcome measures for myasthenia gravis (MG) differ in ease of use, time to completion, what is being measured, how it is being measured, and who reports symptoms and impairments (i.e., patient-reported vs physician-reported).

1–15 Most of these scales are unweighted but a few have weighted test item response options. 3,7,9 The Myasthenia Gravis Composite (MGC) scale consists Cited by: Abstract. Analysis of IUE high- and low-dispersion spectra of the young Herbig Ae star HR (HD ) covering – has revealed dramatic changes in the Mg II h and k (, Å) emission profiles, changes in the column density and distribution in radial velocity of accreting gas, and flux in the Lyα, OI and CIV emission lines, which are correlated with the UV excess Author: M.

R. Pérez, C. A. Grady.