2009MNRAS.394.1075H

Query : 2009MNRAS.394.1075H

2009MNRAS.394.1075H - Mon. Not. R. Astron. Soc., 394, 1075-1084 (2009/April-1)

Local effects in astrometric binary orbits: perspective transformation and light-travel time.

HALBWACHS J.-L.

Abstract (from CDS):

The next generation of astrometric instruments will reach accuracies deserving new treatments. In order to get astrometric parameters achieving the precision permitted by the measurements, it will be necessary to take into account effects that were neglected until the present time. Two effects concerning the orbital elements of binary stars are considered hereafter: the former is the local perspective (LP) effect, which is due to the variation of the distance and of the orientation of the orbital plane during the observation time-span; the equations describing this effect are derived for the first time. The latter effect is the light-travel time (LTT), which is also related to the orientation of the orbital plane, and which is as efficient as the preceding one. Taking these effects into account would allow to find the ascending nodes of the orbits, and lead to orbital elements more accurate than when they are ignored.

It is derived from simulations that, at a distance of 5pc, and assuming velocities typical of Population I stars, the position of the right ascending node could be derived for a few simulated unresolved binaries when the astrometric measurements have errors around 1µas. For the resolved brown dwarf binary 2MASSJ07464256+2000321, it appears that ignoring the LP effect would result in underestimating the masses of the components by 14 per cent of the errors as soon as the astrometric errors are around 20µas for each measurement. However, a `degenerate LP solution', taking into account the variation of the semimajor axis when the distance is varying, should provide reliable masses when the measurement errors are larger than 1 or 2µas. A few binaries in the Gaia program could deserve a degenerate LP solution, whereas a complete LP+LTT solution could be justified for resolved binaries observed with Space Interferometry Mission (SIM).


Abstract Copyright: © 2009 The Author. Journal compilation © 2009 RAS

Journal keyword(s): methods: analytical - astrometry - binaries: general - stars: fundamental parameters - stars: individual: 2MASSJ07464256+2000321

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 - 2026 		#notes
1 LSPM J0746+2000 BD* 07 46 42.56207 +20 00 32.1839       17.9 15.034 L0+L1.5 201 1

Query : 2009MNRAS.394.1075H

Basic data :
LSPM J0746+2000 -- Brown Dwarf
Other object types: otypes_help 		* (2022AJ,AP,...), BD* (2000AJ), ** (2006AJ,**,...), MIR (WISEP,WISE), IR (2MASSI,2MASSW), SB* (2010ApJ), Rad ([B2006]), NIR (2MASS), Opt (SDSS)
ICRS coord. (ep=J2000) : 		07 46 42.56207 +20 00 32.1839 (Near-IR) [ 60 60 0 ] C 2003yCat.2246....0C
FK4 coord. (ep=B1950 eq=1950) : 		07 43 48.25599 +20 07 58.5447 [ 60 60 0 ]
Gal coord. (ep=J2000) : 		200.43742597 +20.83963388 [ 60 60 0 ]
Proper motions mas/yr : 		-370 -42 [4 1 90] D 2003AJ....125..984M
Radial velocity / Redshift / cz : 		V(km/s) 53.863899 [0.042861] / z(spectroscopic) 0.000180 [0.000000] / cz 53.87 [0.04]
   (NIR) A 2020AJ....160..120J
Parallaxes (mas): 		80.9 [0.8] C 2017ApJS..231...15D
Spectral type: 		L0+L1.5 C 2017ApJS..231...15D
Fluxes (11) :
R 17.9 [~] E 2003AJ....125..984M
G 16.689014 [0.009948] C 2020yCat.1350....0G
I 15.034 [0.003] D 2006PASP..118..659L
J 11.759 [0.020] C 2003yCat.2246....0C
H 11.007 [0.022] C 2003yCat.2246....0C
K 10.468 [0.022] C 2003yCat.2246....0C
u (AB) 22.972 [0.489] D 2009ApJS..182..543A
g (AB) 21.186 [0.045] C 2009ApJS..182..543A
r (AB) 18.671 [0.009] B 2009ApJS..182..543A
i (AB) 16.087 [0.004] B 2009ApJS..182..543A
z (AB) 14.243 [0.004] B 2009ApJS..182..543A
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Identifiers (19) :
An access of full data is available using the icon Vizier near the identifier of the catalogue

2MASS J07464256+2000321 LSPM J0746+2000 SDSS J074642.42+200031.8 WISE J074642.23+200031.5
** RED 9 2MASSI J0746425+200032 TIC 62854893 [B2006] J074642.5+200032
AP J07464256+2000321 2MASSW J0746425+200032 USNO-B1.0 1100-00150847 Gaia DR2 672055699133504768
CNS5 1916 2MUCD 10668 WDS J07467+2001AB Gaia DR3 672055699133504768
GSC2 N22110125398 NAME 2M 0746+20 b WISEP J074642.23+200031.5

References (201 between 1850 and 2026) (Total 201)
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 Description of Measurements

Velocities : 6    Distance : 3    Var : 1    Rot : 4    Fe/H : 2    Plx : 5    PM : 8    SpT : 7   

   

External archives :

Data at NED - NASA/IPAC Extragalactic Database : LSPM J0746+2000

Link by name to the catalogue in VizieR :

2MASS J07464256+2000321 AP J07464256+2000321 LSPM J0746+2000 2MASSI J0746425+200032 SDSS J074642.42+200031.8
USNO-B1.0 1100-00150847 WDS J07467+2001AB WISE J074642.23+200031.5 Gaia DR2 672055699133504768 Gaia DR3 672055699133504768

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