2011A&A...532A..78L


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.08CEST04:07:52

2011A&A...532A..78L - Astronomy and Astrophysics, volume 532A, 78-78 (2011/8-1)

Long-period variables in NGC 147 and NGC 185.

LORENZ D., LEBZELTER T., NOWOTNY W., TELTING J., KERSCHBAUM F., OLOFSSON H. and SCHWARZ H.E.

Abstract (from CDS):

Previous studies on the stellar content of the two nearby dwarf galaxies object NGC147 and object NGC185 reveal a rich population of late-type giants in both systems, including a large number of carbon-rich objects. These stars are known to show pronounced photometric variability, which can be used for a more detailed characterisation of these highly evolved stars. Owing to their well-studied parameters, these Local Group members are ideal candidates for comparative studies. Through photometric monitoring, we attempt to provide a catalogue of long-period variables (LPVs), including Mira variables, semi-regular variables, and even irregular variables in object NGC147 and object NGC185 . We investigate the light variations and compare the characteristics of these two LPV populations with the results found for other galaxies, such as the LMC. We carried out time-series photometry in the i-band of the two target galaxies with the Nordic Optical Telescope (NOT), covering a time span of ≃2.5 years. More than 30 epochs were available for a period search. These data were then combined with single-epoch K-band photometry, also obtained with the NOT. Narrow-band photometry data from the literature was used to distinguish between O-rich and C-rich stars. We report the detection of 513 LPVs in NGC185 and 213 LPVs in object NGC147 , showing amplitudes Δi of up to ≃2mag and periods ranging between 90 and 800 days. The period-luminosity diagram for each of our target galaxies exhibits a well populated sequence of fundamental mode pulsators. The resulting period-luminosity relations we obtained are compared to relations from the literature. We discuss the universality of those relations because of which, as a side result, a correction of the distance modulus of object NGC185 may be necessary. A value of (m-M)=24.30mag seems to be more appropriate to match the observed data. Only one of our two galaxies, namely object NGC185 , has a significant fraction of possibly first overtone pulsators. An interpretation of this finding in terms of differences in the star-formation histories is suggested.

Abstract Copyright:

Journal keyword(s): stars: AGB and post-AGB - stars: late-type - stars: variables: general - Local Group - galaxies: individual object: NGC147 - galaxies: individual object: NGC185

VizieR on-line data: <Available at CDS (J/A+A/532/A78): table1.dat table2.dat>

Simbad objects: 10

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Number of rows : 10

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NGC 147 GiG 00 33 12.120 +48 30 31.46   12.0 9.5     ~ 621 1
2 NGC 185 Sy2 00 38 57.970 +48 20 14.56   9.10 9.2     ~ 728 1
3 M 110 GiG 00 40 22.0544552438 +41 41 07.496294862   8.92 8.07     ~ 1207 1
4 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 10903 1
5 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5665 1
6 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14826 1
7 ACO 3526 ClG 12 48 51.8 -41 18 21           ~ 971 2
8 NAME Centaurus A Sy2 13 25 27.61509104 -43 01 08.8056025   8.18 6.84 6.66   ~ 3995 3
9 LDN 663 DNe 19 36 55 +07 34.4           ~ 555 0
10 NAME Local Group GrG ~ ~           ~ 6970 0

    Equat.    Gal    SGal    Ecl

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2020.07.08-04:07:52

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