Preliminary results on the distances, dimensions and space distribution of open star clusters

Trumpler, Robert J.

doi:10.5479/ads/bib/1930licob.14.154t

Cited by 252 publications

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“…HD 194279 (Cyg OB9) is associated to the NGC 6910 cluster which has a distance between 1.7−2.1 kpc (Underhill 1956;Trumpler 1930). McCall et al (2002) report a spectroscopic parallax distance of 1.1 kpc, while Gyul'Budagyan et al (1994) derived a distance of 740 pc for the Cyg OB9 association.…”

Section: Hd 194279mentioning

confidence: 99%

Linear and circular spectropolarimetry of diffuse interstellar bands

Cox

Ehrenfreund

Foing

et al. 2011

A&A

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Context. The identification of the carriers of diffuse interstellar bands (DIBs) remains one of the long-standing mysteries in astronomy. The detection of a polarisation signal in a DIB profile can be used to distinguish between a dust or gas-phase carrier. The polarisation profile can give additional information on the grain or molecular properties of the absorber. Aims. To measure the polarisation efficiency of the carriers of the diffuse interstellar bands. Methods. In order to detect and measure the linear and circular polarisation of the DIBs we observed reddened lines of sight showing continuum polarisation. For this study we selected two stars HD 197770 and HD 194279. We used high-resolution (R ∼ 64 000) spectropolarimetry in the wavelength range from 3700 to 10 480 Å with the ESPaDOnS échelle spectrograph mounted at the CFHT. Results. High S/N and high resolution Stokes V (circular), Q and U (linear) spectra were obtained. We constrained upper limits by a factor of 10 for previously observed DIBs. Furthermore, we analysed ∼30 additional DIBs for which no spectropolarimetry data has been obtained before. This included the 9577 Å DIB and the 8621 Å DIB. The former is attributed to the C + 60 fullerene, which could become aligned in a magnetic field. The latter shows a tight correlation with the amount of dust in the line-of-sight and therefore most likely may show a polarisation signal related the aligned grains. Conclusions. The lack of polarisation in 45 DIB profiles suggests that none of the absorption lines is induced by a grain-type carrier. The strict upper limits, less than ∼0.01%, derived for the observed lines-of-sight imply that if DIBs are due to gas-phase molecules these carriers have polarisation efficiencies which are at least 6 times, and up to 300 times, smaller than those predicted for grainrelated carriers.

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Section: Hd 194279mentioning

confidence: 99%

Linear and circular spectropolarimetry of diffuse interstellar bands

Cox

Ehrenfreund

Foing

et al. 2011

A&A

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“…The existence of interstellar absorption of light was definitively established [17] and many authors contributed to developing models of stellar evolution; O and T associations were discovered [18,19].…”

Section: Historical Informationmentioning

confidence: 99%

The Gould Belt

Бобылев

2014

Astrophysics

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This review is devoted to studies of the Gould belt and the Local system. Since the Gould belt is the giant stellar-gas complex closest to the sun, its stellar component is characterized, along with the stellar associations and diffuse clusters, cold atomic and molecular gas, high-temperature coronal gas, and dust contained in it. Questions relating to the kinematic features of the Gould belt are discussed and the most interesting scenarios for its origin and evolution are examined.

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“…Pismis 23 was described by Ruprecht (1966) as corresponding to Trumpler (1930) class III-2m. With the aim of confirming this object as a genuine cluster, we examined the obtained images searching the region with the highest star density.…”

Section: Pismis 23mentioning

confidence: 99%

Two highly reddened young open clusters located beyond the Sagittarius arm

Piatti

Clariá

2002

A&A

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Abstract. We present the results of CCD BV I Johnson-Cousins photometry down to V ∼ 19 mag in the regions of the unstudied stellar groups Pismis 23 and BH 222, both projected close to the direction towards the Galactic centre. We measured V magnitude and B − V and V − I colours for a total of 928 stars in fields of about 4 ×4 . Pismis 23 is conclusively a physical system, since a clear main sequence and other meaningful features can be seen in the colour-magnitude diagrams. The reality of this cluster is also supported by star counts carried out within and outside the cluster field. For Pismis 23 we derive colour excesses E(B−V ) = 2.0 ± 0.1 and E(V −I) = 2.6 ± 0.1, a distance from the Sun of 2.6 ± 0.6 kpc (Z = −19 pc) and an age of 300 ± 100 Myr (assuming solar metal content). BH 222 appears to be a young open cluster formed by a vertical main sequence and by a conspicuous group of luminous, typically red supergiant stars. We derived for this cluster a colour excess of E(V −I) = 2.4 ± 0.2, a distance from the Sun of 6.0 ± 2.7 kpc (Z = −46 pc) and an age of 60 ± 30 Myr. The resulting reddening and distance estimates place these two young objects among the most reddened and distant open clusters known in the direction towards the Galactic centre. They are located beyond the Sagittarius arm, close to the direction where this arm probably bifurcates into two arms.

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Preliminary results on the distances, dimensions and space distribution of open star clusters

Cited by 252 publications

References 0 publications

Linear and circular spectropolarimetry of diffuse interstellar bands

Linear and circular spectropolarimetry of diffuse interstellar bands

The Gould Belt

Two highly reddened young open clusters located beyond the Sagittarius arm

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