2016A&A...592A..39K


C.D.S. - SIMBAD4 rel 1.7 - 2021.04.13CEST15:25:50

2016A&A...592A..39K - Astronomy and Astrophysics, volume 592A, 39-39 (2016/8-1)

Effects of disc asymmetries on astrometric measurements Can they mimic planets?

KRAL Q., SCHNEIDER J., KENNEDY G. and SOUAMI D.

Abstract (from CDS):

Astrometry covers a parameter space that cannot be reached by RV or transit methods to detect terrestrial planets on wide orbits. In addition, high accuracy astrometric measurements are necessary to measure the inclination of the planet's orbits. Here we investigate the principles of an artefact of the astrometric approach, namely the displacement of the photo-centre owing to inhomogeneities in a dust disc around the parent star. Indeed, theory and observations show that circumstellar discs can present strong asymmetries. We model the pseudo-astrometric signal caused by these inhomogeneities, asking whether a dust clump in a disc can mimic the astrometric signal of an Earth-like planet. We show that these inhomogeneities cannot be neglected when using astrometry to find terrestrial planets. We provide the parameter space for which these inhomogeneities can affect the astrometric signals but still not be detected by mid-IR observations. We find that a small cross section of dust corresponding to a cometary mass object is enough to mimic the astrometric signal of an Earth-like planet. Astrometric observations of protoplanetary discs to search for planets can also be affected by the presence of inhomogeneities. Some further tests are given to confirm whether an observation is a real astrometric signal from a planet or an impostor. Eventually, we also study the case where the cross-section of dust is high enough to provide a detectable IR-excess and to have a measurable photometric displacement by actual instruments such as Gaia, IRAC, or GRAVITY. We suggest a new method, which consists of using astrometry to quantify asymmetries (clumpiness) in inner debris discs that cannot be otherwise resolved.

Abstract Copyright: © ESO, 2016

Journal keyword(s): astrometry - circumstellar matter - protoplanetary disks

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NAME DENIS J082303.1-491201b Pl 08 23 03.1457502969 -49 12 01.265841098           ~ 1 0
2 CPD-36 6759 Y*O 15 15 48.4459023859 -37 09 16.026315179   9.21 8.708     F8V 375 1
3 HD 172555 PM* 18 45 26.9004853 -64 52 16.539796   4.967 4.767     A7V 246 0
4 HD 176051b Pl 18 57 01.60985 +32 54 04.5723           ~ 6 1
5 VB 10 Er* 19 16 57.6103282334 +05 09 01.588675251     17.30     M8V 443 1
6 VB 10 b err 19 16 57.62 +05 09 02.2           ~ 8 2
7 V* AU Mic LM* 20 45 09.5323695486 -31 20 27.241710746   10.05 8.627 9.078 6.593 M1VeBa1 935 0
8 * alf PsA ** 22 57 39.04625 -29 37 20.0533 1.31 1.25 1.16 1.11 1.09 A4V 1138 3

    Equat.    Gal    SGal    Ecl

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2021.04.13-15:25:50

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