Dust properties along anomalous extinction sightlines

Mazzei, P.; Barbaro, G.

doi:10.1051/0004-6361/201014867

Cited by 9 publications

(38 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We combine the λ max values from this work with the results of WD01 best-fit models of Mazzei & Barbaro (2011, their Table 4), and compute the Pearson's correlation coefficient, ρ, and the p-value for testing non-correlation between λ max and their derived dust-to-gas ratio ( ρ d ρ H ), carbon and silicon abundances compared to solar values ( C C , Si Si ), R V value, the ratio between reddening and total hydrogen column density ( E(B−V) N H ), and smallto-large grain size ratios of carbon (R C ) and silicon (R Si ). They considered grains as small if their size is 0.01 µm, and other- wise as large.…”

Section: Discussionmentioning

confidence: 99%

“…HD 137569 is an interesting case because it has relatively high reddening E(B − V) ∼ 0.40 mag (Mazzei & Barbaro 2011), but its polarization degree is consistent with zero ( Fig. 1).…”

Section: Hd 137569mentioning

confidence: 96%

“…The properties of dust grains towards the considered stars were obtained in Mazzei & Barbaro (2008) where the authors performed theoretical models fitting to the anomalous extinction curves. The authors found that to reproduce the anomalous extinction, silicate grains must be concentrated in small sizes of a < 0.1 µm (see also Mazzei & Barbaro 2011). Such small silicate grains cannot reproduce the normal λ max that is measured.…”

Section: Dust Properties Inferred From Simulationsmentioning

confidence: 99%

“…We selected our targets from the samples presented by Mazzei & Barbaro (2008. Mazzei & Barbaro (2011) obtained 785 extinction curves for sightlines with E(B − V) 0.2 mag (Savage et al 1985), observed with the Astronomical Netherlands Satellite (ANS) in five UV bands (1/λ = 6.46, 5.56, 4.55, 4.01 and 3.04 µm −1 ) (Wesselius et al 1982). They combined the UV observations with Two-Micron All-Sky Survey (2MASS) observations in the near-infrared J, H and K bands, applied a least square fit of the standard Cardelli, Clayton, & Mathis (1989) extinction curve (CCM) with different R V values, and determined the residual differences between the observed values and best-fit CCM curve at five UV wavelengths.…”

Section: Target Samplementioning

confidence: 99%

See 3 more Smart Citations

Spectropolarimetry of Galactic stars with anomalous extinction sightlines

Cikota

Hoang

Taubenberger

et al. 2018

A&A

View full text Add to dashboard Cite

Highly reddened type Ia Supernovae (SNe Ia) with low total-to-selective visual extinction ratio values, R V , also show peculiar linear polarization wavelength dependencies with peak polarizations at short wavelengths (λ max 0.4µm). It is not clear why sightlines to SNe Ia display such different continuum polarization profiles from interstellar sightlines in the Milky Way with similar R V values. We investigate polarization profiles of a sample of Galactic stars with low R V values, along anomalous extinction sightlines, with the aim to find similarities to the polarization profiles that we observe in SN Ia sightlines. We undertook spectropolarimetry of 14 stars, and used archival data for three additional stars, and run dust extinction and polarization simulations (by adopting the picket-fence alignment model) to infer a simple dust model (size distribution, alignment) that can reproduce the observed extinction and polarization curves. Our sample of Galactic stars with low R V values and anomalous extinction sightlines displays normal polarization profiles with an average λ max ∼ 0.53µm, and is consistent within 3σ to a larger coherent sample of Galactic stars from literature. Despite the low R V values of dust towards the stars in our sample, the polarization curves do not show any similarity to the continuum polarization curves observed towards SNe Ia with low R V values. There is a correlation between the best-fit Serkowski parameters K and λ max , but we did not find any significant correlation between R V and λ max . Our simulations show that the K-λ max relationship is an intrinsic property of polarization. Furthermore, we have shown that in order to reproduce polarization curves with normal λ max and low R V values, a population of large (a ≥ 0.1µm) interstellar silicate grains must be contained in the dust's composition.

show abstract

Section: Discussionmentioning

confidence: 99%

“…HD 137569 is an interesting case because it has relatively high reddening E(B − V) ∼ 0.40 mag (Mazzei & Barbaro 2011), but its polarization degree is consistent with zero ( Fig. 1).…”

Section: Hd 137569mentioning

confidence: 96%

Section: Dust Properties Inferred From Simulationsmentioning

confidence: 99%

Section: Target Samplementioning

confidence: 99%

See 2 more Smart Citations

Spectropolarimetry of Galactic stars with anomalous extinction sightlines

Cikota

Hoang

Taubenberger

et al. 2018

A&A

View full text Add to dashboard Cite

show abstract

“…Hence, NIR spectroscopic (DIB) surveys may reveal their presence in the interstellar medium (ISM). Several ongoing and A&A 569, A117 (2014) Cox et al (2005) and HD 161061 taken from Mazzei & Barbaro (2011) . (b) Intrinsic colours from (1) Wegner (1994) and (2) Fitzgerald (1970).…”

Section: Introductionmentioning

confidence: 99%

VLT/X-Shooter survey of near-infrared diffuse interstellar bands

Cox

Cami

Kaper

et al. 2014

A&A

View full text Add to dashboard Cite

Context. The unknown identity of the diffuse interstellar band (DIB) carriers poses one of the longest standing unresolved problems in astrophysics. While the presence, properties, and behaviour of hundreds of optical DIBs between 4000 Å and 9000 Å have been well established, information on DIBs in both the ultra-violet and near-infrared (NIR) ranges is limited. Aims. In this paper, we present a spectral survey of the NIR range, from 0.9 µm to 2.5 µm. Our observations were designed to detect new DIBs, confirm previously proposed NIR DIBs, and characterise their behaviour with respect to known line-of-sight properties (including the optical DIBs present in our spectra). Methods. Using the X-Shooter instrument mounted on the ESO Very Large Telescope (VLT) we obtained medium-resolution spectra of eight known DIB targets and one telluric reference star, from 3000 Å to 25 000 Å in one shot.Results. In addition to the known 9577, 9632, 10 780, 11 797, and 13 175 Å NIR DIBs, we confirm 9 out of the 13 NIR DIBs that were presented by Geballe et al. (2011, Nature, 479, 200). Furthermore, we report 11 new NIR DIB candidates. The strengths of the strongest NIR DIBs show a general correlation with reddening, E (B − V) , but with a large scatter. Several NIR DIBs are more strongly correlated with the 5780 Å DIB strength than with E (B − V) ; this is especially the case for the 15 268 Å DIB. The NIR DIBs are strong: the summed equivalent widths of the five strongest NIR DIBs represent a small percent of the total equivalent width of the entire average DIB spectrum (per unit reddening). The NIR DIBs towards the translucent cloud HD 147889 are all weak with respect to the general trend. No direct match was found between observed NIR DIBs and laboratory matrix-isolation spectroscopic data of polycyclic aromatic hydrocarbons (PAHs). Conclusions. The strong correlation between the 5780−15 268 DIB pair implies that (N f ) 5780 /(N f ) 15 268 = 14. However, the reduced strength of the 15 268 Å DIB in HD 147889 rules out a common carrier for these two DIBs. Since the ionisation fraction for small PAHs in this translucent cloud is known to be low compared to diffuse clouds, the weakness of the 15 268 Å DIB suggests that an ionised species could be the carrier of this NIR DIB.

show abstract

Interstellar extinction and interstellar polarization: Old and new models

Вощинников

2012

Journal of Quantitative Spectroscopy and Radiative Transfer

View full text Add to dashboard Cite

The review contains an analysis of the observed and model curves of the interstellar extinction and polarization. The observations mainly give information on dust in diffuse and translucent interstellar clouds. The features of various dust grain models including spherical/non-spherical, homogeneous/inhomogeneous particles are discussed. A special attention is devoted to the analysis of the grain size distributions, alignment mechanisms and magnetic field structure in interstellar clouds. It is concluded that the interpretation of interstellar extinction and polarization is not yet complete.

show abstract

Dust properties along anomalous extinction sightlines

Cited by 9 publications

References 48 publications

Spectropolarimetry of Galactic stars with anomalous extinction sightlines

Spectropolarimetry of Galactic stars with anomalous extinction sightlines

VLT/X-Shooter survey of near-infrared diffuse interstellar bands

Interstellar extinction and interstellar polarization: Old and new models

Contact Info

Product

Resources

About