Assessment of the near infrared identification of carbon stars

Battinelli, P.; Demers, S.

doi:10.1051/0004-6361:200810619

Cited by 15 publications

(18 citation statements)

References 28 publications

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“…In their study of IC 1613, Battinelli & Demers (2009) conclude that a cut at (J − K s ) = 1.40 mag would provide a reliable sample of C-type stars. From Fig.…”

Section: Colour Selection 331 C-and M-type Agb Starsmentioning

confidence: 99%

“…M-type sources were then selected between 0.75 ≤ (J − K) 0 < 1.15 mag and C-type sources were selected at (J − K) 0 ≥ 1.15 mag. A red (J − K) limit was not applied for the selection of the C-type candidates as these sources have been shown to extend to least (J − K) 0 ∼ 2.4 mag (Battinelli & Demers 2009) in IC 1613, and the relatively few sources in our C-type sample with colours redder than this may still be genuine AGB stars that are heavily enshrouded by dust (Zijlstra et al 2006). …”

Section: Blue Limit To M-type Giantsmentioning

confidence: 99%

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The AGB population in IC 1613 usingJHKphotometry

Sibbons

Ryan

Irwin

et al. 2014

A&A

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Context. A member of the Local Group, IC 1613 is a gas rich irregular dwarf galaxy that appears to have formed stars continuously over the last 10 Gyr and is relatively independent of external influences from other galaxies. Aims. This paper aims to study the spatial distribution of the asymptotic giant branch (AGB) population in IC 1613 and its metallicity. Methods. Using WFCAM on UKIRT, high quality JHK photometry of an area of 0.8 deg 2 centered on IC 1613 was obtained. The data have been used to isolate the C-and M-type components of the AGB population and using their number ratio, C/M, a global mean metallicity has been derived. The metallicity and the tip of the red giant branch magnitude (TRGB) have been studied as a function of distance from the galactic centre and as a function of azimuthal angle. Results. The TRGB has been found to be at K 0 = 18.25 ± 0.15 mag. The colour separation between the C-and M-type components of the AGB population has been located at (J − K) 0 = 1.15 ± 0.05 mag, giving a global C/M ratio of 0.52 ± 0.04 and from this an iron abundance of [Fe/H] = −1.26 ± 0.07 dex has been calculated. Conclusions. The AGB population has been detected out to a radial distance of 4.5 kpc in the de-projected plane of the galaxy. The measured TRGB is consistent with previous measurements and no significant variation is detected in the TRGB or in metallicity either with galactocentric distance or azimuthal angle.

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“…In their study of IC 1613, Battinelli & Demers (2009) conclude that a cut at (J − K s ) = 1.40 mag would provide a reliable sample of C-type stars. From Fig.…”

Section: Colour Selection 331 C-and M-type Agb Starsmentioning

confidence: 99%

Section: Blue Limit To M-type Giantsmentioning

confidence: 99%

The AGB population in IC 1613 usingJHKphotometry

Sibbons

Ryan

Irwin

et al. 2014

A&A

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“…Different techniques adopted for searching C stars lead to samples with different biases (see Battinelli & Demers 2009). The reddest stars are too faint in the optical spectral range to be detected with objective grating techniques, while the four‐filter technique misses the bluest stars (Demers & Battinelli 2002).…”

Section: Colour–magnitude Diagramsmentioning

confidence: 99%

A near-infrared study of AGB and red giant stars in the Leo I dSph galaxy

Held¹,

Gullieuszik²,

Rizzi³

et al. 2010

Monthly Notices of the Royal Astronomical Society

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A near-infrared imaging study of the evolved stellar populations in the dwarf spheroidal galaxy Leo I is presented. Based on JHK observations obtained with the WFCAM wide-field array at the United Kingdom Infrared Telescope, we build a near-infrared photometric catalogue of red giant branch (RGB) and asymptotic giant branch (AGB) stars in Leo I over a 13.5 arcmin2 area. The V - K colours of RGB stars, obtained by combining the new data with existing optical observations, allow us to derive a distribution of global metallicity [M/H] with average [M/H] = -1.51 (uncorrected) or [M/H] =-1.24 +/- 0.05(int) +/- 0.15(syst) after correction for the mean age of Leo I stars. This is consistent with the results from spectroscopy once stellar ages are taken into account. Using a near-infrared two-colour diagram, we discriminate between carbon- and oxygen-rich AGB stars and obtain a clean separation from Milky Way foreground stars. We reveal a concentration of C-type AGB stars relative to the red giant stars in the inner region of the galaxy, which implies a radial gradient in the intermediate-age (1-3 Gyr) stellar populations. The numbers and luminosities of the observed carbon- and oxygen-rich AGB stars are compared with those predicted by evolutionary models including the thermally pulsing AGB phase, to provide new constraints to the models for low-metallicity stars. We find an excess in the predicted number of C stars fainter than the RGB tip, associated to a paucity of brighter ones. The number of O-rich AGB stars is roughly consistent with the models, yet their predicted luminosity function is extended to brighter luminosity. Although these discrepancies can be partly ascribed to significant uncertainties in the Leo I star formation history and incompleteness of the spectroscopic samples of C stars fainter than the RGB tip, it appears more likely that the adopted evolutionary models overestimate the C-star lifetime and underestimate their K-band luminosity

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“…The color separations of the C stars from the M-giant stars were determined at (H − K s ) > 0.45 and (J − K s ) > 1.28, where the histogram of M-giant stars drops significantly. The applied color limit in (J − K s ) of the C stars is somewhat bluer than the color limit of (J − K) 0 = 1.4 used in several previous studies (Davidge 2005;Kang et al 2006;Battinelli et al 2007b;Battinelli & Demers 2009). We note that spectroscopic data are necessary for a more accurate identification of M-giant and C stars.…”

Section: Color−color Diagrams and The Selection Of The C Stars Of Ic mentioning

confidence: 61%

“…We note that spectroscopic data are necessary for a more accurate identification of M-giant and C stars. However, Battinelli & Demers (2009) discussed that many C stars probably have a bluer color than the (J − K) 0 = 1.4 limit, and Kacharov et al (2012) indeed found in their spectroscopic data of NGC 6822 that several of the C stars in NGC 6822 have a bluer color than this limit. Thus, our color limit for the C stars is reasonable compared with the other conditions.…”

Section: Color−color Diagrams and The Selection Of The C Stars Of Ic mentioning

confidence: 93%

Near-infrared photometric properties of asymptotic giant branch stars in the dwarf irregular galaxy IC 1613

Chun

Jung

Kang

et al. 2015

A&A

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Aims. We investigated the photometric properties of asymptotic giant branch (AGB) stars of the dwarf irregular galaxy IC 1613 and its metallicity. Methods. We used near-infrared JHK s photometric data obtained with the WIRCam array on Canada-France-Hawaii Telescope (CFHT). The optical gi imaging data of a previous study were cross-matched with ours to distinguish the stellar populations in the galaxy and to select the AGB stars. We also separated the C stars from the M-giant stars in the JHK s color−color diagram. Results. We identified 140 C stars and 306 M-giant stars in IC 1613. The (J − K s ) color histogram of AGB stars shows the main peak of M-giant stars and the red tail of C stars. The broad color distribution of M-giant stars and the isochrones in the color magnitude diagram indicate that IC 1613 has a wide range of intermediate-age stars. We also know that most C stars were formed over the past 2−8 Gyr according the M bol -age relation. The C/M ratio of 0.46 ± 0.05 was estimated and [Fe/H] abundance of −1.23 ± 0.06 was derived from the C/M ratio. Radial distributions of C/M ratio and metallicity show the shallow trend of the negative metallicity gradient from the center. The local C/M ratio also indicates that the HI cavity has higher C/M values than the bright HI spot and HI gas region. However, the low [Fe/H] value near the central region of the galaxy is likely to be caused by the change in age of the dominant stellar population according to the radial distance, not the real metallicity variation. It might also be that relatively younger and metal-rich C stars are concentrated in the center of the galaxy, while the M-giant stars were homogeneously distributed from the center to the borders of the galaxy.

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Assessment of the near infrared identification of carbon stars

Cited by 15 publications

References 28 publications

The AGB population in IC 1613 usingJHKphotometry

The AGB population in IC 1613 usingJHKphotometry

A near-infrared study of AGB and red giant stars in the Leo I dSph galaxy

Near-infrared photometric properties of asymptotic giant branch stars in the dwarf irregular galaxy IC 1613

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