2003A&A...404L..43B

Query : 2003A&A...404L..43B

2003A&A...404L..43B - Astronomy and Astrophysics, volume 404, L43-46 (2003/6-4)

The optical counterpart to SAX J1808.4-3658 in quiescence: Evidence of an active radio pulsar?

BURDERI L., DI SALVO T., D'ANTONA F., ROBBA N.R. and TESTA V.

Abstract (from CDS):

The optical counterpart of the binary millisecond X-ray pulsar SAX J1808.4-3658 during quiescence was detected at V=21.5mag by Homer et al. (2001MNRAS.325.1471H). This star shows a 6% semi-amplitude sinusoidal modulation of its flux at the orbital period of the system. It was proposed that the modulation arises from X-ray irradiation of the intrinsically faint companion by a remnant accretion disk, and that the bulk of the optical emission arises from viscous dissipation in the disk. The serious difficulty in this scenario lies in the estimate of the irradiating luminosity required to match the observational data, that is a factor 10-50 higher than the quiescent X-ray luminosity of this source. To overcome this problem, we propose an alternative scenario, in which the irradiation is due to the release of rotational energy by the fast spinning neutron star, switched on, as magneto-dipole rotator (radio pulsar), during quiescence. Our computations indicate that the optical magnitudes are fully consistent with this hypothesis. In this case the observed optical luminosity may be the first evidence that a radio pulsar is active in this system in quiescence, a key phase for understanding the evolution of this class of objects.

Abstract Copyright: ∼

Journal keyword(s): accretion discs - stars: individual: SAX J1808.4-3658 - stars: neutron - X-rays: stars - X-rays: binaries - X-rays: general

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 V* V4580 Sgr LXB 18 08 27.54 -36 58 44.3   16.81 16.51     ~ 984 0

Query : 2003A&A...404L..43B

Basic data :
V* V4580 Sgr -- Low Mass X-ray Binary
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: 		X (PBC,SAX,...), LXB (2013ApJS), Psr (PSR), N* (2014MNRAS), V* (V*), * ([RCM98]), gam (INTREF)
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) : 		18 08 27.54 -36 58 44.3 [ ] D 1999MNRAS.304...47G
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) : 		18 05 03.46 -36 59 13.8 [ ]
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) : 		355.38501 -08.14826 [ ]
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 (2) :
B 16.81 [~] D 2007A&A...469..807L
V 16.51 [~] D 2007A&A...469..807L
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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within arcsec The VizieR photometry tool allows for easy visualization of photometry points extracted around the Simbad position from photometry-enabled catalogues in VizieR.
The search radius has to be specified by the user. It is currently limited to a maximum of 30 arcsec. It depends mostly on the precision or quality of the coordinates (SIMBAD and VizieR catalogs), the resolution of the images from which the sources were extracted, source extent, and source crowding.
Suggestions are: crowded field: 0.5 to 1.5 arcsec, 3 arcsec otherwise; uncertain coordinates (SIMBAD quality E or coordinates without reference): 5 to 30 arsec (risky!). sed-help-icon

The link on the acronym of the identifiers give access to the information for this acronym in the dictionary of nomenclature.
Identifiers (8) :
An access of full data is available using the icon Vizier near the identifier of the catalogue

INTREF 881 PSR J1808-3658 SWIFT J1808.5-3655 XTE J1808-369
PBC J1808.3-3656 SAX J1808.4-3658 V* V4580 Sgr [RCM98] J180827.5-365842

References (984 between 1850 and 2024) (Total 984)
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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Observing logs


XMM : 4   

   

External archives :

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

Data at NED - NASA/IPAC Extragalactic Database : V* V4580 Sgr

Link by name to the catalogue in VizieR :

V* V4580 Sgr

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