Radio emission from pre-main-sequence stars in Corona Australis

1987 ◽  
Vol 322 ◽  
pp. L31 ◽  
Author(s):  
Alexander Brown
Keyword(s):  
Radio Emission ◽  
Main Sequence ◽  
Main Sequence Stars

scholarly journals A Radio Survey of Older T Tauri Stars in the η Chamaeleontis Cluster

1999 ◽  
Vol 16 (3) ◽  
pp. 257-261 ◽  
Author(s):  
Eric E. Mamajek ◽  
Warrick A. Lawson ◽  
Eric D. Feigelson
Keyword(s):  
Radio Emission ◽  
Main Sequence ◽  
T Tauri Stars ◽  
Young Stars ◽  
Radio Continuum ◽  
Rotating Stars ◽  
Main Sequence Stars ◽  
X Ray ◽  
Rotation Periods ◽  
T Tauri

AbstractA radio continuum survey of X-ray-identified weak-lined T Tauri stars (WTTs) in the newly-discovered η Chamaeleontis cluster has been completed using the Australia Telescope Compact Array (ATCA). The 10 known WTTs in the cluster form a unique sample of codistant late-type pre-main-sequence stars with ages of ~8 Myr and masses ranging from 0·1–1·0 M⊙. Our survey detected none of the 10 X-ray-emitting WTTs with 3σ sensitivity limits at 4·8 and 8·6 GHz (6·2 and 3·5 cm) of typically 0·4 mJy, corresponding to a radio luminosity of 4·5 ×1015 erg Hz−1 s−1. Rotation periods for these stars indicate that they are not, as a group, fast-rotating stars. The non-detection in the radio bands supports the findings of other radio surveys of inhomogeneous samples of young stars, where radio emission is fairly common (10–30%) among very young T Tauri stars across all late spectral types, but confined to rapidly-rotating F-G-K stars amongst older zero-age main sequence stars. Rotation, more than youth, appears to be the key to radio emission in young stars.

scholarly journals Circumstellar radio emission from pre-main sequence stars

1987 ◽  
Vol 122 ◽  
pp. 63-64
Author(s):  
Alexander Brown
Keyword(s):  
Radio Emission ◽  
Main Sequence ◽  
Radio Continuum ◽  
Circumstellar Envelopes ◽  
Main Sequence Stars ◽  
Radio Jets ◽  
Extended Radio ◽  
Upper Limits ◽  
Infra Red ◽  
Pms Stars

VLA radio continuum observations have been obtained for a number of pre-main sequence (PMS) stars in Corona Australis, Lupus, Scorpius and Taurus. A variety of PMS sources were detected and for other stars upper limits to the ionized mass loss rates were determined. A strong double source, showing two radio jets, was found associated with an embedded infra-red source in the R CrA molecular cloud. Some of the PMS stars show extended radio emission associated with ionized circumstellar envelopes, even though photoionization by EUV photons is not sufficient to produce the ionized regions.

scholarly journals Radio Emission From Stellar Flares

1989 ◽  
Vol 104 (1) ◽  
pp. 163-185
Author(s):  
Jan Kuijpers
Keyword(s):  
Radio Emission ◽  
Main Sequence ◽  
Magnetic Energy ◽  
Compact Stars ◽  
Double Layers ◽  
Close Binaries ◽  
Main Sequence Stars ◽  
Stellar Flares ◽  
Coherent Emission ◽  
Flare Process

AbstractAn overview is given of the observations of stellar radio ‘flares', defined as radio emission which is both variable in time and created by explosive releases of magnetic energy. The main sources of such flares are late-type Main-Sequence stars, classic close binaries, X-ray binaries, and pre-Main-Sequence stars.We summarize the interpretations of these observations in terms of the various incoherent and coherent emission mechanisms. The possible importance of a coherent emission process in electrostatic double layers is pointed out.We briefly indicate the diagnostic importance of radio emission for the flare process in classic and compact stars. In particular we discuss the possible production of radio flares from interactions between an accretion disk and the magnetic field of the central object.

scholarly journals Magnetic coronae of active main-sequence stars

2008 ◽  
Vol 4 (S259) ◽  
pp. 357-362 ◽  
Author(s):  
Moira Jardine ◽  
Jean-Francois Donati
Keyword(s):  
Binary System ◽  
Radio Emission ◽  
Solar Corona ◽  
Internal Structure ◽  
Main Sequence ◽  
The Sun ◽  
Coronal Structure ◽  
Main Sequence Stars ◽  
X Ray ◽  
Recent Advances

AbstractThe coronal structure of main sequence stars continues to puzzle us. While the solar corona is relatively well understood, it has become clear that even stars of the same mass as the Sun can display very non-solar coronal behaviour, particularly if they are rapid rotators or in a binary system. At masses greater than and also less than that of the Sun, the non-solar internal structure appears to affect both the geometry and dynamics of the stellar corona and the nature of the X-ray and radio emission. In this talk I will describe some recent advances in our understanding of the structure of the coronae of some of the most active (and interesting) main sequence stars.

Chromospheric activity as a function of age in main-sequence stars

1966 ◽  
Vol 24 ◽  
pp. 40-43
Author(s):  
O. C. Wilson ◽  
A. Skumanich
Keyword(s):  
Main Sequence ◽  
The Sun ◽  
Main Sequence Stars ◽  
Tentative Conclusion ◽  
Chromospheric Activity ◽  
General Field ◽  
Large Clusters

Evidence previously presented by one of the authors (1) suggests strongly that chromospheric activity decreases with age in main sequence stars. This tentative conclusion rests principally upon a comparison of the members of large clusters (Hyades, Praesepe, Pleiades) with non-cluster objects in the general field, including the Sun. It is at least conceivable, however, that cluster and non-cluster stars might differ in some fundamental fashion which could influence the degree of chromospheric activity, and that the observed differences in chromospheric activity would then be attributable to the circumstances of stellar origin rather than to age.

On The Radii of Ap Stars

1976 ◽  
Vol 32 ◽  
pp. 49-55 ◽  
Author(s):  
F.A. Catalano ◽  
G. Strazzulla
Keyword(s):  
Observational Data ◽  
Line Width ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Ap Stars

SummaryFrom the analysis of the observational data of about 100 Ap stars, the radii have been computed under the assumption that Ap are main sequence stars. Radii range from 1.4 to 4.9 solar units. These values are all compatible with the Deutsch's period versus line-width relation.

A Search for Radio Emission at the Bottom of the Main Sequence and Beyond

1999 ◽  
Vol 118 (3) ◽  
pp. 1369-1372 ◽  
Author(s):  
Anita Krishnamurthi ◽  
Giuseppe Leto ◽  
Jeffrey L. Linsky
Keyword(s):  
Radio Emission ◽  
Main Sequence

Pre–Main-Sequence Stars in the Young Galactic Cluster IC 4996: A CCD Photometric Study

1998 ◽  
Vol 116 (4) ◽  
pp. 1801-1809 ◽  
Author(s):  
Antonio J. Delgado ◽  
Emilio J. Alfaro ◽  
André Moitinho ◽  
José Franco
Keyword(s):  
Main Sequence ◽  
Photometric Study ◽  
Main Sequence Stars ◽  
Galactic Cluster
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