2014A&A...567A..60G


Query : 2014A&A...567A..60G

2014A&A...567A..60G - Astronomy and Astrophysics, volume 567A, 60-60 (2014/7-1)

Searching for visual companions of close Cepheids. VLT/NACO lucky imaging of Y Oph, FF Aql, X Sgr, W Sgr, and η Aql.

GALLENNE A., KERVELLA P., MERAND A., EVANS N.R., GIRARD J.H.V., GIEREN W. and PIETRZYNSKI G.

Abstract (from CDS):

High-resolution imaging in several photometric bands can provide color and astrometric information of the wide-orbit component of Cepheid stars. Such measurements are needed to understand the age and evolution of pulsating stars. In addition, binary Cepheids have the potential to provide direct and model-independent distances and masses. We used the NAOS-CONICA adaptive optics instrument (NACO) in the near-infrared to perform a deep search for wide components around the classical Cepheids, Y Oph, FF Aql, X Sgr, W Sgr, and η Aql, within a field of view of 1.7''x1.7'' (3.4''x3.4'' for η Aql). We were able to reach contrast ΔH=5-8mag and ΔKs=4-7mag in the radius range r>0.2'', which enabled us to constrain the presence of wide companions. For Y Oph, FF Aql, X Sgr, W Sgr, and η Aql at r>0.2'', we ruled out the presence of companions with a spectral type that is earlier than a B7V, A9V, A9V, A1V, and G5V star, respectively. For 0.1''< r < 0.2'', no companions earlier than O9V, B3V, B4V, B2V, and B2V star, respectively, are detected. A component is detected close to η Aql at projected separation ρ=654.7±0.9mas and a position angle PA=92.8±0.1°. We estimated its dereddened apparent magnitude to be mH0=9.34±0.04 and derived a spectral type that ranges between an F1V and an F6V star. Additional photometric and astrometric measurements are necessary to better constrain this star and check its physical association to the η Aql system.

Abstract Copyright:

Journal keyword(s): instrumentation: adaptive optics - techniques: high angular resolution - stars: variables: Cepheids - binaries: visual

Simbad objects: 14

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Number of rows : 14
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 * alf UMi cC* 02 31 49.09456 +89 15 50.7923 3.00 2.62 2.02 1.53 1.22 F8Ib 628 2
2 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 15461 1
3 V* V659 Cen cC* 13 31 33.4103851030 -61 34 56.514647163 7.57 7.19 6.49     F6/7Ib+B6V 98 0
4 V* S Nor cC* 16 18 51.8313333962 -57 53 59.253617873 8.15 7.49 6.49   5.427 F8/G0Ib 350 1
5 HD 159527 * 17 35 43.8120430462 -14 38 37.262112565   9.26 7.55     K4III 10 0
6 V* X Sgr cC* 17 47 33.6241002643 -27 49 50.848981593 5.84 5.34 4.54 6.03 3.661 F7II 317 0
7 V* Y Oph cC* 17 52 38.7021149511 -06 08 36.875163136 8.62 7.61 6.21     G3Ia 348 0
8 * gam01 Sgr cC* 18 05 01.2265190154 -29 34 48.303215344 5.99 5.47 4.69   3.869 G0Ib/II 332 0
9 HD 166295 * 18 11 05.2169828438 -25 45 44.191159228   8.12 6.68     K2III/IV 14 0
10 HD 175743 PM* 18 56 06.1211306975 +18 06 19.471537953       5.0   K1III 68 0
11 V* FF Aql cC* 18 58 14.7482217777 +17 21 39.295590199 6.61 6.18 5.38     F6Ib 347 0
12 * eta Aql cC* 19 52 28.3677478 +01 00 20.369619 5.12 4.61 3.80   3.030 F6Iab+B9.8V 644 0
13 * bet Aql PM* 19 55 18.7925630 +06 24 24.342501 5.040 4.560 3.710 3.05 2.56 G8IV 522 0
14 V* V1334 Cyg cC* 21 19 22.1772463169 +38 14 14.867388528   6.364 5.882     F1II+B7.0V 182 0

    Equat.    Gal    SGal    Ecl

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2021.07.23-21:51:24

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