The X-ray shadow of the high-latitude molecular cloud MBM 12

Snowden, S. L.; McCammon, D.; Verter, Frances

doi:10.1086/186850

Cited by 81 publications

(54 citation statements)

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“…Snowden et al (2000) determined an I local count rate of only (3.7 ± 0.4) × 10 −4 cts s −1 arcmin −2 in the ROSAT R12 energy band. This is quantitatively equal to the I local count rate observed towards MBM 12 (Snowden et al 1993) with (3.7±0.4)×10 −4 cts s −1 arcmin −2 . However, MBM12 is located at a distance of (360 ± 30) pc (Andersson et al 2002).…”

Section: Hrk 814-778: Distance Estimate Derived From Interstellar Rsupporting

confidence: 62%

Star formation in a diffuse high-altitude cloud?

Kerp¹,

Lenz²,

Roehser³

2016

A&A

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Context. A recent discovery of two stellar clusters associated with the diffuse high-latitude cloud HRK 81.4-77.8 has important implications for star formation in the Galactic halo. Aims. We derive a plausible distance estimate to HRK 81.4-77.8 primarily from its gaseous properties. Methods. We spatially correlate state-of-the-art HI, far-infrared and soft X-ray data to analyze the diffuse gas in the cloud. The absorption of the soft X-ray emission from the Galactic halo by HRK 81.4-77.8 is used to constrain the distance to the cloud. Results. HRK 81.4-77.8 is most likely located at an altitude of about 400 pc within the disk-halo interface of the Milky Way Galaxy. The HI data discloses a disbalance in density and pressure between the warm and cold gaseous phases. Apparently, the cold gas is compressed by the warm medium. This disbalance might trigger the formation of molecular gas high above the Galactic plane on pc to sub-pc scales.

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Section: Hrk 814-778: Distance Estimate Derived From Interstellar Rsupporting

confidence: 62%

Star formation in a diffuse high-altitude cloud?

Kerp¹,

Lenz²,

Roehser³

2016

A&A

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“…Smith et al (2005) repeated the MBM 12 observations using the CHANDRA ACIS instrument in August 2000, but their results were adversely influenced by a strong C,oronal Mass Ejection (CME). They measured particularly strong O VII and O VIII line emission with a surface brightness of 1.79±0.55 LU and 2.34±0.36 LU respectively, much larger than Snowden et al (1993)'s limits. They argued that this intense oxygen line emission could not come from any of the standard LHB models, either equilibrium or strongly recombining, and suggested that their results were contaminated by SWCX.…”

Section: Introductionmentioning

confidence: 69%

“…the exact distance of MBM 12 is not important, since the cloud is nearer than the nonlocal sources of the SXRB in the 3 kcV band. Snowden et al (1993) first observed NIBM 12 as an X-ray shadow with ROSAT in order to ineasure the LHB soft X-ray emission in the 1 keV and -3 keV energy bands. They placed a.…”

Section: Introductionmentioning

confidence: 99%

XMM-NEWTONOBSERVATIONS OF MBM 12: MORE CONSTRAINTS ON THE SOLAR WIND CHARGE EXCHANGE AND LOCAL BUBBLE EMISSIONS

Koutroumpa

Edgar

Küntz

et al. 2010

ApJ

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We present the first analysis of an XMAI-Newton observation of the nearby molecular cloud MBNI 12. We find that in the direction of MBM 12 the total O VII (0.57 keV) triplet emission is 1.8+0" photons cm -2 s _u sr -1 (or Line Units -LU) while for the O VIII (0.65 keV) line emission we find a 3Q upper limit of <1 LU. We also use a heliospheric model to calculate the O VII and O VIII emission generated by Solar Wind Charge-eXchange (SWCX) which we compare to the XMM-Newton observations. This comparison provides new constraints on the relative heliospheric and Local Bubble contributions to the local diffuse X-ray background. The heliospheric SWCX model predicts 0.82 LU for O VII, which accounts for -,16±15 eic of the observed value, and 0.33 LU for the O VIII line emission consistent with the XMM-Newton observed value. We discuss our results in combination with previous observations of the MBM 12 with CHANDRA and Suzaku.

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“…The first one is the well known local X-ray radiation originating within the local void of neutral matter. Its radiation dominates the emission within the ROSAT 1/4keV band, while it is nearly undetectable in the ROSAT3/4keV and 1.5keV energy bands (Snowden et al 1993). Also well known is the radiation of the extragalactic X-ray background.…”

Section: T H E Soft X-ray Backgroundmentioning

confidence: 99%

High-Velocity Clouds and their Soft X-ray Emission

Kerp

Pietz

Kalberla

et al. 1997

International Astronomical Union Colloquium

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Abstract. Diffuse excess 1/4 keV soft X-ray emission was found to be positionally correlated with the column density distribution of the high velocity cloud (HVC) complex C (Kerp et al. 1996). Here we point out that the detected diffuse X-ray emission is indeed associated with the HVC phenomenon. For this purpose we study the 1/4 keV radiation transfer as well as the Hi column density distribution of HVCs and intermediate velocity clouds (IVCs) towards HVC complex C in detail. We present evidence that on arcmin scales the 3/4 keV soft X-ray emission is positionally anticorrelated with the HVC column density distribution of an individual HVC filament of complex C. IntroductionUp to now HVCs have been detected, in emission, only in the line radiation of the neutral atomic hydrogen (for a comprehensive review see Wakker & van Woerden 1997). Recent analyses of ROSAT data, suggest that HVCs also emit soft X-rays (Herbstmeier et al. 1995and Kerp et al. 1994, 1995, 1996. Here we focus on HVC complex C towards high galactic latitudes. We present a comparative analysis of X-ray and HI 21 cm line data available in this region (73° < I < 118°, 38° < b < 63°). In the l/4keV energy regime one has to disentangle the X-ray emission of the individual soft X-ray sources which contribute to the observed X-ray background in order to reveal the excess emission associated with the HVCs. Especially the intermediate-and low-velocity gas determines the intensity distribution of the soft X-ray sky, by photoelectric absorption. Because of the much smaller absorption cross section in the 3/4 keV band such a decomposition is not necessary. We will demonstrate that it is feasible to separate the emission of the "normal" soft X-ray background (SXRB) from that of the excess emission associated with HVCs. In consequence we have to solve the radiation transport of soft X-ray photons through the galactic interstellar medium (ISM) to identify sky areas which reveal deviations from this "normal" SXRB intensity distribution. Here we focus on two aspects which are important to understanding the recent results on X-ray emission of HVCs. First, we will show that the ROSAT 1/4 keV all-sky survey data reveal soft X-ray emission which is positionally correlated with the HVCs of complex C. We show new H121 cm line maps of the total and IVC column density distribution and discuss the relation of the individual cloud populations to the appearance of the soft X-ray intensity distribution on the sky. Second, we will discuss in Sect. 3 the small scale positional association of an individual HVC filament with excess soft X-ray emission in the ROSAT 3/4keV energy band. This is of importance because the 3/4 keV radiation can penetrate the galactic ISM without significant attenuation towards high galactic latitudes. T h e Soft X-ray BackgroundIt is a matter of discussion whether the SXRB has a patchy source intensity distribution or not (see also Pietz et al., Snowden, and Wang; this volume). For our purpose knowledge of the soft X-ray intensity distribution on ...

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The X-ray shadow of the high-latitude molecular cloud MBM 12

Cited by 81 publications

References 0 publications

Star formation in a diffuse high-altitude cloud?

Star formation in a diffuse high-altitude cloud?

XMM-NEWTONOBSERVATIONS OF MBM 12: MORE CONSTRAINTS ON THE SOLAR WIND CHARGE EXCHANGE AND LOCAL BUBBLE EMISSIONS

High-Velocity Clouds and their Soft X-ray Emission

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