Observations of interstellar ultraviolet extinction from the S2/68 experiment in the TD-1 satellite

Nandy, K.; Thompson, G. I.; Carnochan, D. J.; Wilson, R.

doi:10.1093/mnras/184.4.733

Cited by 10 publications

(3 citation statements)

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“…We confirm the existence of a significant depression in both the diffuse and total FUV maps at high latitudes above less intense segments of the Galactic plane from l = 20 • to l = 60 • , as noted in Schiminovich et al (2001) and Gondhalekar et al (1980). Gondhalekar et al (1980) showed that this direction corresponds to one of the most heavily reddened directions in the sky by comparing the FUV map with the reddening data of Nandy et al (1978). We also confirmed the strong reddening toward this direction with the more recent results given by Arenou et al (1992), Chen et al (1998), andJoshi (2005).…”

Section: Morphologysupporting

confidence: 87%

Observation of the Far-Ultraviolet Continuum Background With Spear/Fims

Seon

Edelstein

Korpela

et al. 2011

ApJS

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We present the general properties of the far-ultraviolet (FUV; 1370-1710 Å) continuum background over most of the sky, obtained with the Spectroscopy of Plasma Evolution from Astrophysical Radiation instrument (SPEAR, also known as FIMS), flown aboard the STSAT-1 satellite mission. We find that the diffuse FUV continuum intensity is well correlated with N HI , 100 µm, and Hα intensities but anti-correlated with soft X-ray intensity. The correlation of the diffuse background with the direct stellar flux is weaker than the correlation with other parameters. The continuum spectra are relatively flat. However, a weak softening of the FUV spectra toward some sight lines, mostly at high Galactic latitudes, is found not only in direct-stellar but also in diffuse background spectra. The diffuse background is relatively softer than the direct stellar spectrum. We also find that the diffuse FUV background averaged over the sky has a bit softer spectrum compared to direct stellar radiation. A map of the ratio of 1370-1520 Å to 1560-1710 Å band intensity shows that the sky is divided into roughly two parts. However, this map shows a lot of patchy structures on small scales. The spatial variation of the hardness ratio seems to be largely determined by the longitudinal distribution of OB-type stars in the Galactic plane. A correlation of the hardness ratio with the FUV intensity at high intensities is found but an anti-correlation at low intensities. We also find evidence that the FUV intensity distribution is log-normal in nature.

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Section: Morphologysupporting

confidence: 87%

Observation of the Far-Ultraviolet Continuum Background With Spear/Fims

Seon

Edelstein

Korpela

et al. 2011

ApJS

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“…Bottom panel: Residuals, χ: differences between synthetic and observed magnitudes divided by the corresponding uncertainties. The photometric systems have the following color code: UV magnitudes from the TD1 satellite (violet;Nandy et al 1978) labeled with central wavelengths, optical magnitudes from Tycho2(Høg et al 2000), Hipparcos (van Leeuwen 2007), Gaia (blue Gaia Collaboration 2020), andMermilliod (2006); IR photometry from 2MASS (redCutri et al 2003) and DENIS(yellowDenis 2005). Right hand panel: color indices in the Johnson (cyan) and Geneva (red) systems(Mermilliod 2006;Rufener 1988).…”

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confidence: 99%

The origin of early-type runaway stars from open clusters

Bhat

Irrgang

Heber

2022

A&A

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Runaway stars are ejected from their place of birth in the Galactic disk, with some young B-type runaways found several tens of kiloparsecs from the plane traveling at speeds beyond the escape velocity, which calls for violent ejection processes. Young open clusters are a likely place of origin, and ejection may be either through N-body interactions or in binary supernova explosions. The most energetic events may require dynamical interaction with massive black holes. The excellent quality of Gaia astrometry opens up the path to study the kinematics of young runaway stars to such a high precision that the place of origin in open stellar clusters can be identified uniquely even when the star is a few kiloparsecs away. We developed an efficient minimization method to calculate whether two or more objects may come from the same place, which we tested against samples of Orion runaways. Our fitting procedure was then used to calculate trajectories for known runaway stars, which have previously been studied from Hipparcos astrometry as well as known open clusters. For runaways in our sample we used Gaia data and updated radial velocities, and found that only half of the sample could be classified as runaways. The other half of the sample moves so slowly (<30 km s −1 ) that they have to be considered as walkaway stars. Most of the latter stars turned out to be binaries. We identified parent clusters for runaways based on their trajectories. We then used cluster age and flight time of the stars to investigate whether the ejection was likely due to a binary supernova or due to a dynamical ejection. In particular we show that the classical runaways AE Aurigae and µ Columbae might not have originated together, with µ Columbae having an earlier ejection from Collinder 69, a cluster near the ONC. The second sample investigated comprises a set of distant runaway B stars in the halo which have been studied carefully by quantitative spectral analyses. We are able to identify candidate parent clusters for at least four stars including the hyper-runaway candidate HIP 60350. The ejection events had to be very violent, ejecting stars at velocities as large as 150 to 400 km s −1 .

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“…S1nce our program stars are confined to the galactic plane and have measurable color excesses, we tried to estimate their distances. We used the graphs of FitzGerald (1968), Lucke (1978), Nandy et al (1978), and in some cases Perry and Johnston (1982), and to M V . Our results for LSII +18 0 9 and LSIV +10 0 9 agree well with those of Walker ( 1981) who found M y N 7 and M y > 3.2, respectively.…”

Section: The Hr-diagram and The Evolution Of Sdo'smentioning

confidence: 99%

Effective temperatures and luminosities of very hot O type subdwarfs

Schönberner

Drilling

1984

ApJ

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We observed 12 very hot 0-type subdwarfs with the IUE-satellite in the low dispersion mode. We derived temperatures from the slopes of the UVcontinua and estimated distances from the col g r excesses. Most of them are hotter than 60,000 K, i.e. they are the hottest known subdwarfs. From their spectral appearance and location in a H.R.-diagram they form a rather i nhomogeneous group. Three of them turned out to be central stars or nearly central stars, and four are definitely near the white dwarf stage. The surface helium to hydrogen ratio varies from about normal to the extreme case. Most of them appear to be post EHB objects of 0.5 M o with a helium burning shell as their energy source, and their peculiar helium-to-hydrogen ratios are most likely the result of diffusion and convective mixing in surface layers.

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Observations of interstellar ultraviolet extinction from the S2/68 experiment in the TD-1 satellite

Cited by 10 publications

References 0 publications

Observation of the Far-Ultraviolet Continuum Background With Spear/Fims

Observation of the Far-Ultraviolet Continuum Background With Spear/Fims

The origin of early-type runaway stars from open clusters

Effective temperatures and luminosities of very hot O type subdwarfs

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