2002A&A...383..218S

Query : 2002A&A...383..218S

2002A&A...383..218S - Astronomy and Astrophysics, volume 383, 218-226 (2002/2-3)

Spin-up of Be stars in the pre-main sequence phase.

STEPIEN K.

Abstract (from CDS):

In an attempt to explain faster than average rotation of Be stars, a model for rotational evolution of a pre-main sequence (PMS) star with a weak primordial magnetic field was applied to stars with masses between 3 and 7 solar mass. The model takes into account the accretion of matter along the magnetic field lines, the stellar field-disk interaction and a magnetized wind. Evolutionary changes of the stellar moment of inertia are also included. The stellar mass and magnetic flux were assumed constant during the PMS evolution. The results indicate that magnetic accretion spins up a star early in its PMS life and if the star has a short PMS life time (i.e. high enough mass), it may keep faster rotation until the zero age main sequence (ZAMS). Detailed calculations show that typically a factor of two faster rotation is achieved compared to the conserved angular momentum case. This requires an intense accretion going on for a substantial fraction of the PMS phase in the presence of a surface magnetic field not exceeding 400G. Stronger fields slow down the stellar rotation very efficiently by the magnetic field-disk locking mechanism. Low mass stars with PMS life time significantly longer than the time scale of spin down by the magnetic wind may be efficiently braked by the wind operating after the disappearance of the disk. They can retain faster than average rotation only under very special conditions. It is postulated that ZAMS progenitors of Be stars possess fossil magnetic fields with surface intensity between 40 and 400G. The fields result in rotation rates about two times higher than those of normal stars in full agreement with the observations. If the observed Be stars have already evolved from ZAMS, their present magnetic fields should be correspondingly weaker due to the evolutionary increase of the stellar radius. ZAMS stars with magnetic fields weaker than about 40G should have normal rotation and those with fields significantly stronger than 400G should become slowly rotating Ap-Bp magnetic stars. The case of β Cephei, with its present surface magnetic field close to 400G, is a special case of an intermediate field, strong enough to slow down the star's rotation in the PMS phase but apparently not strong enough to develop Bp star characteristics.

Abstract Copyright: ∼

Journal keyword(s): stars: emission-line, Be - stars: magnetic fields - stars: pre-main sequence - stars: rotation

Simbad objects: 1

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Number of rows : 1
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024 		#notes
1 * bet Cep bC* 21 28 39.5968513 +70 33 38.574681 2.05 3.01 3.23 3.33 3.55 B0.5IIIs 725 0

Query : 2002A&A...383..218S

Basic data :
* bet Cep -- beta Cep Variable
Origin of the objects types :

(Ref) Object type as listed in the reference "Ref"
(acronym) Object type linked to the acronym according to the original reference
() Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases

Other object types: 		* (*,AG,...), ** (**,ADS,...), V* (2012ApJ,V*,...), SB* (SBC7,SBC9), X (2E,2XMM), UV (EUVE,TD1), bC* (2022A&A), NIR (2MASS), IR (IRAS)
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
ICRS coord. (ep=J2000) : 		21 28 39.5968513 +70 33 38.574681 (Optical) [ 0.30 0.26 90 ] A 2007A&A...474..653V
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
FK4 coord. (ep=B1950 eq=1950) : 		21 28 01.2938682 +70 20 27.660072 [ 0.30 0.26 90 ]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
Gal coord. (ep=J2000) : 		107.5392080196 +14.0261114044 [ 0.30 0.26 90 ]
Syntax of proper motions is : "pm-ra pm-dec [error ellipse] quality bibcode"
  • pm-ra : mu-ra*cos(dec) (expressed in the ICRS system in mas/yr)
  • pm-dec : mu-dec (expressed in the ICRS system in mas/yr)
  • [error ellipse] : error major axis and minor axis (in mas), orientation angle (in deg)
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the proper motion reference
Proper motions mas/yr : 		12.54 8.39 [0.37 0.27 90] A 2007A&A...474..653V
Syntax of radial velocity (or/and redshift) is : "value [error] (wavelength) quality bibcode"
  • value : radial velocity or/and redshift (Heliocentric frame) according to your Output Options
    (redshift may be not displayed if the data value is <0 and the database inside value is a radial velocity)
  • [error] : error of the corresponding value displayed before
  • (wavelength) : wavelength range of the measurement : Rad, mm, IR, Opt, UV, Xray, Gam or  '∼'(unknown)
  • quality : flag of quality ( A=best quality -> E=worst quality, ∼=unknown quality)
  • bibcode : bibcode of the value's origin
Radial velocity / Redshift / cz : 		V(km/s) -8.2 [2] / z(~) -0.000027 [0.000007] / cz -8.20 [2.00]
   E 1953GCRV..C......0W
Syntax of parallax is : 'value quality [error] bibcode'
  • value : parallax value
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • [error] : mean error
  • bibcode : bibcode of the parallax reference
Parallaxes (mas): 		4.76 [0.30] A 2007A&A...474..653V
Spectral type is made of 3 parts: %coding is composed of 4 parts :
  • the spectral type, which is made of a temperature class, eventually a luminosity class (roman number) and/or spectral peculiarities;
  • a quality letter: A=best quality→E=worst quality, {� } =unknown quality %
  • a quality letter: A=best quality -> E=worst quality, {� } =unknown quality
  • bibcode : bibcode of the spectral type reference
Spectral type: 		B0.5IIIs C 1983ApJ...272..182A
Syntax of fluxes (or magnitudes) is : "filter-name (System) flux-value [error] quality MultVarFlags bibcode"
  • filter-name : U, B, V, R, I, G, J, H, K, u, g, r, i, z
  • (System) : may be AB (default is Vega)
  • flux-value : value of flux or magnitude
  • [error] : error value
  • quality : flag of quality of the flux value ( A=best quality -> E=worst quality, {� } =unknown quality)
  • MultVarFlags : Mult is zero or one char (J) for joined photometry ; Var can be zero or two chars (V[0-4])
  • bibcode : bibcode of the flux reference
Fluxes (9) :
U 2.05 [~] C 2002yCat.2237....0D
B 3.01 [~] C 2002yCat.2237....0D
V 3.23 [~] C 2002yCat.2237....0D
R 3.33 [~] C 2002yCat.2237....0D
G 3.194590 [0.008950] C 2022yCat.1355....0G
I 3.55 [~] C 2002yCat.2237....0D
J 3.78 [~] C 2002yCat.2237....0D
H 3.75 [0.22] D 2003yCat.2246....0C
K 3.96 [~] C 2002yCat.2237....0D
SIMBAD within arcmin
', {sourceSize:12, color:'#30a090'})); aladin.on('objectClicked', function(object) { var objName=object.data.MAIN_ID; aladin.showPopup(object.ra,object.dec,'',''+ objName+''); });" title="Show Simbad objects"> Overlay Simbad points in this preview
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The link on the acronym of the identifiers give access to the information for this acronym in the dictionary of nomenclature.
Identifiers (53) :
An access of full data is available using the icon Vizier near the identifier of the catalogue

* bet Cep FK5 809 MCW 989 TYC 4465-2643-1
* 8 Cep GC 30118 N30 4748 UBV 21582
** LAB 6 GCRV 13520 NAME Alfirk V* bet Cep
** STF 2806A GEN# +1.00205021A PLX 5192 WDS J21287+7034Aa,Ab
ADS 15032 A GSC 04465-02643 PMC 90-93 568 WDS J21287+7034A
AG+70 738 HD 205021 PMSC 21274+7007AP WEB 19222
AKARI-IRC-V1 J2128395+703338 HGAM 1007 PPM 10863 2XMM J212839.3+703338
ALS 14839 HIC 106032 ROT 3532 [HFE83] 1440
BD+69 1173 HIP 106032 SAO 10057 AAVSO 2127+70
CCDM J21287+7034A HR 8238 SBC7 859 Gaia DR3 2272185759996420992
CSI+69 1173 1 IDS 21274+7007 A SBC9 1310 Gaia DR2 2272185759992826624
2E 4480 IRAS 21280+7020 SKY# 40953
2E 2128.0+7020 JP11 3361 TD1 28199
EUVE J2128+70.5 2MASS J21283958+7033389 TIC 321818578

References (725 between 1850 and 2024) (Total 725)
Simbad bibliographic survey began in 1850 for stars (at least bright stars) and in 1983 for all other objects (outside the solar system).
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Collections of Measurements


velocities : 18    ROT : 6    Fe_H : 6    PLX : 3    PM : 5    MK : 28   

   

Observing logs


ISO : 1    IUE : 89   

   

External archives :

Archive data at HEASARC - High-Energy Astrophysics Science Archive Research Center

Data at NED - NASA/IPAC Extragalactic Database : * bet Cep

Link by name to the catalogue in VizieR :

AG+70 738 AKARI-IRC-V1 J2128395+703338 ALS 14839 BD+69 1173 CCDM J21287+7034A
2E 4480 EUVE J2128+70.5 FK5 809 GSC 04465-02643 HD 205021
HIC 106032 HIP 106032 HR 8238 IRAS 21280+7020 2MASS J21283958+7033389
PLX 5192 PPM 10863 SAO 10057 TD1 28199 TYC 4465-2643-1
V* bet Cep WDS J21287+7034Aa,Ab WDS J21287+7034A Gaia DR3 2272185759996420992 Gaia DR2 2272185759992826624

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