Cool carbon stars in the halo and in dwarf galaxies: H<i>α</i>, colours, and variability

Mauron, N.; Gigoyan, K. S.; Berlioz-Arthaud, Paul; Klotz, A.

doi:10.1051/0004-6361/201322794

Cited by 11 publications

(22 citation statements)

References 58 publications

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“…Our primary source, providing just over half of all our variable carbon stars, comes from the lists published by the Mauron group (Mauron et al 2004;Mauron, Kendall, & Gigoyan 2005;Mauron, Gigoyan, & Kendall 2007b;Mauron 2008;Mauron et al 2014). These were selected from candidates based on 2MASS (Skrutskie et al 2006) photometry and then spectroscopically confirmed.…”

Section: Mauron Et Al Samplementioning

confidence: 99%

“…There may be artefacts in the period determination for both Mauron et al (2014) and ourselves, due to the cadence of the Catalina observations that we both use, so it is also valuable to compare our periods to other data sets. A few stars are also shared between our first sample and that of Battinelli & Demers (2012, 2013, and allow us to compare the periods determined.…”

Section: Period Determinationmentioning

confidence: 99%

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Tracing the tidal streams of the Sagittarius dSph, and halo Milky Way features, with carbon-rich long-period variables

Huxor

Grebel

2015

Mon. Not. R. Astron. Soc.

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We assemble 121 spectroscopically-confirmed halo carbon stars, drawn from the literature, exhibiting measurable variability in the Catalina Surveys. We present their periods and amplitudes, which are used to estimate distances from period-luminosity relationships. The location of the carbon stars -and their velocities when availableallow us to trace the streams of the Sagittarius (Sgr) dwarf spheroidal galaxy. These are compared to a canonical numerical simulation of the accretion of Sgr. We find that the data match this model well for heliocentric distances of 15-50 kpc, except for a virtual lack of carbon stars in the trailing arm just north of the Galactic Plane, and there is only tentative evidence of the leading arm south of the Plane. The majority of the sample can be attributed to the Sgr accretion. We also find groups of carbon stars which are not part of Sgr; most of which are associated with known halo substructures. A few have no obvious attribution and may indicate new substructure. We find evidence that there may be a structure behind the Sgr leading stream apocentre, at ∼100 kpc, and a more distant extension to the Pisces Overdensity also at ∼100 kpc. We study a further 75 carbon stars for which no good period data could be obtained, and for which NIR magnitudes and colours are used to estimate distances. These data add support for the features found at distances beyond 100 kpc.

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Section: Mauron Et Al Samplementioning

confidence: 99%

Section: Period Determinationmentioning

confidence: 99%

Tracing the tidal streams of the Sagittarius dSph, and halo Milky Way features, with carbon-rich long-period variables

Huxor

Grebel

2015

Mon. Not. R. Astron. Soc.

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“…The observed K and J magnitudes are available only at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/568/A100 distribution with those of similar variables of other stellar populations. Recently Mauron et al (2014) have determined periods for a much larger sample of halo C stars. They find that the period distribution of the halo Miras matches rather well a similar distribution for the Sgr Miras observed by Battinelli & Demers (2013), thus suggesting a probable common origin.…”

Section: Introductionmentioning

confidence: 99%

“…Since most of our new program stars now have periods determined by Mauron et al (2014), we prefer here to discuss the fraction of Miras among C stars and investigate their NIR colors.…”

Section: Introductionmentioning

confidence: 99%

Miras among C stars

Battinelli

Demers

2014

A&A

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Context. Carbon stars are among the brightest intermediate-age stars. They are seen in nearly all galaxies of the Local Group. In the Milky Way they are members of the thin disk but over a hundred have been identified in the Galactic halo. Since the halo consists essentially of an old stellar population, these carbon stars warrant special attention. We believe that such stars are trespassers and belong to streams left over by disrupted dwarf spheroidal galaxies. Aims. By performing photometric monitoring we intend to identify Miras among the halo carbon stars. Methods. We obtained, over several semesters, K and J images centered on the carbon stars in order to determine their variation and periodicity. Results. We establish the variability for a number of stars and identify the Miras among them. We collect data from the literature on the Miras among various carbon star populations and show that the fraction of Miras among carbon stars is fairly constant. We demonstrate that such fractions for the halo and Sagittarius are biased because of the way targets are selected. We finally investigate the near-infrared color distribution of Miras and carbon stars.

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“…Bessel & Brett 1988;Leggett et al 2002;Cruz et al 2003). We show the results in Figure 4 together with those of confirmed carbon stars from FBS and other dataset (Alksnis et al 2001;Mauron 2008;Mauron et al 2014). The positions of V381 Lac corresponding to the dates reported in Table 2 are indicated by the numbers in black.…”

Section: Infrared Diagramsmentioning

confidence: 97%

The variable V381 Lac and its possible connection with the R CrB phenomenon

Rossi¹,

Dell’Agli²,

Paola³

et al. 2015

Mon. Not. R. Astron. Soc.

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We have performed new medium resolution spectroscopy, optical and near infrared photometry to monitor the variability of the AGB carbon star V 381 Lac. Our observations revealed rapid and deep changes in the spectrum and extreme variability in the optical and near infrared bands. Most notably we observed the change of NaI D lines from deep absorption to emission, and the progressive growing of the [N ii] doublet 6548-6584Å emission, strongly related to the simultaneous photometric fading. V381 Lac occupies regions of 2MASS and WISE colour-colour diagrams typical of stars with dust formation in the envelope. The general framework emerging from the observations of V381 Lac is that of a cool AGB carbon star undergoing episodes of high mass ejection and severe occultation of the stellar photosphere reminiscent of those characterising the RCB phenomenon.Comparing the Spectral Energy Distribution obtained with the theoretical model for AGB evolution with dust in the circumstellar envelope, we can identify V381 Lac as the descendant of a star of initial mass ∼2M , in the final AGB phases, evolved into a carbon star by repeated Third Dredge Up episodes. According to our model the star is moderately obscured (τ 10 ∼ 0.22) by dust, mainly formed by amorphous carbon (∼ 80%) and SiC (∼ 20%), with dust grain dimensions around ∼ 0.2µm and 0.08µm respectively.

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Cool carbon stars in the halo and in dwarf galaxies: Hα, colours, and variability

Cited by 11 publications

References 58 publications

Tracing the tidal streams of the Sagittarius dSph, and halo Milky Way features, with carbon-rich long-period variables

Tracing the tidal streams of the Sagittarius dSph, and halo Milky Way features, with carbon-rich long-period variables

Miras among C stars

The variable V381 Lac and its possible connection with the R CrB phenomenon

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