Infrared photometry of southern early-type stars

Whittet, D. C. B.; Breda, I. G. van

doi:10.1093/mnras/192.3.467

Cited by 90 publications

(83 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The intrinsic colors of the stars with spectral types earlier than A0 (V < 14.4 mag) have been obtained using Q-method (Johnson & Morgan 1953) The ratio of total-to-selective extinction is estimated by using the relation (Whittet & van Breda 1980) and it is found to be 2.9 ± 0.3, which is in agreement with the normal value of 3.1 within 1σ limit, thus, indicating a normal grain size in the direction of cluster.…”

Section: Interstellar Extinctionmentioning

confidence: 64%

Stellar contents and star formation in the young cluster Stock 18

2012

View full text Add to dashboard Cite

We have carried out deep (V∼21 mag) UBVRI photometric study of the star cluster Stock 18. These along with archival Infrared data have been used to derive the basic cluster parameters and also to study the star formation processes in and around the cluster region. The distance to the cluster is derived as 2.8±0.2 kpc while its age is estimated as 6.0 ± 2.0 Myr. Present study indicates that interstellar reddening is normal in the direction of the cluster. The mass function slope is found to be -1.37±0.27 for the mass range 1< M/M ⊙ <11.9. There is no evidence found for the effect of mass segregation in main-sequence stars of the cluster. A young stellar population with age between 1-2 Myr have been found in and around the cluster region. The presence of IRAS and AKARI sources with MSX intensity map also show the youth of the Sh2-170 region.

show abstract

Section: Interstellar Extinctionmentioning

confidence: 64%

Stellar contents and star formation in the young cluster Stock 18

2012

View full text Add to dashboard Cite

show abstract

“…We adopted a standard selective absorption coefficient, R v = 3.1 (Schultz & Wiemer 1975;Whittet & van Breda 1980;Rieke & Lebofsky 1985). The distance modulus of a cluster is the average value of all individual member determinations.…”

Section: Fundamental Parameters Of the Clustermentioning

confidence: 99%

Open clusters

Aidelman

Cidale

Zorec

et al. 2012

A&A

View full text Add to dashboard Cite

Context. Spectroscopic investigations of galactic open clusters are scarce and limited to a reduced sample of cluster members. Aims. We intend to perform a complete study of the physical parameters of two galactic clusters as well as of their individual members. Methods. To carry out this study, we used the BCD (Barbier-Chalonge-Divan) spectrophotometric system, which is based on the study of the Balmer discontinuity and is independent of interstellar and circumstellar extinction. Additional physical properties were derived from the line profiles (FWHM) and stellar evolution models. We analyzed low-resolution spectra around the Balmer discontinuity for normal B-type and Be stars in two open clusters: NGC 3766 and NGC 4755. We determined the stellar fundamental parameters, such as effective temperatures, surface gravities, spectral types, luminosity classes, absolute and bolometric magnitudes, and color gradient excesses. The stellar rotation velocity was also determined. Complementary information, mainly stellar mass, age, and radius of the star population were calculated using stellar evolution models. In some cases, the stellar fundamental parameters were derived for the first time. The obtained results allowed us also to determine the reddening, age, and distance to the clusters. Results. The cluster parameters obtained through the BCD method agree very well with those derived from classical methods based on photometric data. The BCD system also provides physical properties of the star members. This study enables us to test the good behavior of M bol (λ 1 , D)-calibrations and detect systematic discrepancies between log g estimates from model atmospheres and those derived from stellar evolution models. To improve our knowledge on the formation and evolution of the clusters, more statistical studies on the initial mass luminosity and angular momentum distributions should be addressed. Therefore, the BCD spectrophotometric system could be a powerful tool for studying far galactic and extragalactic clusters with the generation of large telescopes and the multi-object technique.

show abstract

“…We recall here some milestones in the knowledge about HD 120678: Serkowski (1968) reported that this star is intrinsically polarized; Strohmeier (1972) found light variability; Whittet & van Breda (1978) detected a large infrared excess; and Meyer & Savage (1981) found peculiar UV extinction parameters. Finally, using IUE data, Massa et al (1983) found that its A&A 546, A92 (2012) UV spectrum is that of a normal late-O dwarf, although based on the previous work, it had been concluded that HD 120678 was an Oe-type star with normal extinction, its visual and IR colors being affected by circumstellar emission.…”

Section: Introductionmentioning

confidence: 96%

The discovery of a shell-like event in the O-type star HD 120678

Gamen

Arias

Barbá

et al. 2012

A&A

View full text Add to dashboard Cite

Aims. We report the detection of a shell-like event in the Oe-type star HD 120678. Methods. HD 120678 has been intensively observed as part of a high-resolution spectroscopic monitoring program of southern Galactic O stars and Wolf-Rayet stars of the nitrogen sequence.Results. An optical spectrogram of HD 120678 obtained in June 2008 shows strong H and He i absorption lines instead of the double-peaked emission profiles observed both previously and subsequently, as well as a variety of previously undetected absorption features, mainly of O ii, Si iii and Fe iii. Photometric data reveal that the development of the absorption spectrum coincided with a remarkable dip in the V-band lightcurve. The "shell phase" of HD 120678 did not persist for very long: the V magnitude recovered its previous average value in fewer than 120 days, whereas H and He emission lines became detectable one year later. Similar spectral variations have been observed in a few Be stars, and they are usually interpreted as changes in the circumstellar disk.

show abstract

Infrared photometry of southern early-type stars

Cited by 90 publications

References 0 publications

Stellar contents and star formation in the young cluster Stock 18

Stellar contents and star formation in the young cluster Stock 18

Open clusters

The discovery of a shell-like event in the O-type star HD 120678

Contact Info

Product

Resources

About