Displacement of the Sun from the Galactic plane

Joshi, Y. C.

doi:10.1111/j.1365-2966.2007.11831.x

Cited by 97 publications

(83 citation statements)

References 42 publications

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“…Similar results have been found by the studies using young open clusters and OB stars (see e.g. Joshi 2007). The FWHM of our distribution is ∼1 • , while in ATLASGAL this is more narrow, ∼0.…”

Section: Galactic Scale Extinctionsupporting

confidence: 80%

Initial phases of massive star formation in high infrared extinction clouds

Rygl

Wyrowski

Schüller

et al. 2010

A&A

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Aims. The earliest phases of massive star formation are found in cold and dense infrared dark clouds (IRDCs). Since the detection method of IRDCs is very sensitive to the local properties of the background emission, we present here an alternative method to search for high column density in the Galactic plane by using infrared extinction maps. Using this method we find clouds between 1 and 5 kpc, of which many were missed by previous surveys. By studying the physical conditions of a subsample of these clouds, we aim at a better understanding of the initial conditions of massive star formation. Methods. We have made extinction maps of the Galactic plane based on the 3.6−4.5 μm color excess between the two shortest wavelength Spitzer IRAC bands, reaching to visual extinctions of ∼100 mag and column densities of 9 × 10 22 cm −2 . From this we compiled a new sample of cold and compact high extinction clouds. We used the MAMBO array at the IRAM 30 m telescope to study the morphology, masses and densities of the clouds and the dense clumps within them. The latter were followed up by pointed ammonia observations with the 100 m Effelsberg telescope, to determine rotational temperatures and kinematic distances. Results. Extinction maps of the Galactic plane trace large scale structures such as the spiral arms. The extinction method probes lower column densities, N H 2 ∼ 4 × 10 22 cm −2 , than the 1.2 mm continuum, which reaches up to N H 2 ∼ 3 × 10 23 cm −2 but is less sensitive to large scale structures. The 1.2 mm emission maps reveal that the high extinction clouds contain extended cold dust emission, from filamentary structures to still diffuse clouds. Most of the clouds are dark in 24 μm, but several show already signs of star formation via maser emission or bright infrared sources, suggesting that the high extinction clouds contain a variety of evolutionary stages. The observations suggest an evolutionary scheme from dark, cold and diffuse clouds, to clouds with a stronger 1.2 mm peak and to finally clouds with many strong 1.2 mm peaks, which are also warmer, more turbulent and already have some star formation signposts.

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Section: Galactic Scale Extinctionsupporting

confidence: 80%

Initial phases of massive star formation in high infrared extinction clouds

Rygl

Wyrowski

Schüller

et al. 2010

A&A

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“…For this purpose, we adopt a reference frame with origin at the Galactic center, with the z-axis pointing to the northern Galactic pole and with the x-axis pointing in the direction from the Sun to the Galactic center. With respect to this reference frame, the Sun is located at R = (−8.5, 0, 0.03) kpc (Ghez et al 2008, Gillessen et al 2009, Reid et al 2009, Joshi 2007) and has a peculiar velocity of (10, 5, 7) km s −1 (Bienaymé 1999). With the given R and peculiar velocity, the Sun is moving at a velocity V = (10, 226, 7) km s −1 .…”

Section: Methods Of Calculationmentioning

confidence: 99%

“…The distribution is normalized to unity by setting n 0 = 1/(4πh z h 2 R ). Since the progenitors of DNS are distributed in the same way as the massive stellar binaries in our galaxy, we choose h R = 2.8 kpc and h z = 0.07 kpc (see Joshi 2007). For all of the observed DNS except PSR B1534+12, we use a population of ∼10 9 simulated binaries.…”

Section: Methods Of Calculationmentioning

confidence: 99%

Constraints on Natal Kicks in Galactic Double Neutron Star Systems

Wong

Willems

Kalogera

2010

ApJ

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Since the discovery of the first double neutron star (DNS) system in 1975 by Hulse and Taylor, there are currently eight confirmed DNS in our galaxy. For every system, the masses of both neutron stars, the orbital semimajor axis, and eccentricity are measured, and proper motion is known for half of the systems. Using the orbital parameters and kinematic information, if available, as constraints for all systems, we investigate the immediate progenitor mass of the second-born neutron star (NS2) and the magnitude of the supernova kick it received at birth, with the primary goal to understand the core-collapse mechanism leading to neutron star formation. Compared to earlier studies, we use a novel method to address the uncertainty related to the unknown radial velocity of the observed systems. For PSR B1534+12 and PSR B1913+16, the kick magnitudes are 150-270 km s −1 and 190-450 km s −1 (with 95% confidence), respectively, and the progenitor masses of the NS2 are 1.3-3.4 M and 1.4-5.0 M (95%), respectively. These suggest that the NS2 was formed by an iron core-collapse supernova in both systems. For PSR J0737−3039, on the other hand, the kick magnitude is only 5-120 km s −1 (95%), and the progenitor mass of the NS2 is 1.3-1.9 M (95%). Because of the relatively low progenitor mass and kick magnitude, the formation of the NS2 in PSR J0737−3039 is potentially connected to an electron capture supernova of a massive O-Ne-Mg white dwarf. For the remaining five Galactic DNS, the kick magnitude ranges from several tens to several hundreds of km s −1 , and the progenitor mass of the NS2 can be as low as ∼1.5 M or as high as ∼8 M . Therefore, in these systems it is not clear which type of supernova is more likely to form the NS2.

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“…In our calculation we use R ⊙ = (x ⊙ , y ⊙ , z ⊙ ) = (−8400, 0, 17) in pc. Since the vertical position of the Sun with respect to the Galactic disk plane is still uncertain we decided to follow arguments of Joshi (2007) and adopt z ⊙ =+17 pc. The reader should be warned that during this translation we kept the orientation of all axes, so in a Galactocentric frame the OX axis is directed opposite to the Sun direction, the OY is directed in accordance to the Sun rotation around the Galactic centre and the OZ axis is directed to the north Galactic pole, what makes this system a right-handed one.…”

Section: Units Definitions Reference Framesmentioning

confidence: 99%

On the accuracy of close stellar approaches determination

Dybczyński

Berski

2015

Monthly Notices of the Royal Astronomical Society

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The aim of this paper is to demonstrate the accuracy of our knowledge of close stellar passage distances in the pre-GAIA era. We used the most precise astrometric and kinematic data available at the moment and prepared a list of 40 stars nominally passing (in the past or future) closer than 2 pc from the Sun. We used a full gravitational potential of the Galaxy to calculate the motion of the Sun and a star from their current positions to the proximity epoch. For this calculations we used a numerical integration in rectangular, Galactocentric coordinates. We showed that in many cases the numerical integration of the star motion gives significantly different results than popular rectilinear approximation. We found several new stellar candidates for close visitors in past or in future.We used a covariance matrices of the astrometric data for each star to estimate the accuracy of the obtained proximity distance and epoch. To this aim we used a Monte Carlo method, replaced each star with 10 000 of its clones and studied the distribution of their individual close passages near the Sun. We showed that for contemporary close neighbours the precision is quite good but for more distant stars it strongly depends on the quality of astrometric and kinematic data. Several examples are discussed in detail, among them the case of HIP 14473. For this star we obtained the nominal proximity distance as small as 0.22 pc 3.78 Myr ago. However there exist strong need for more precise astrometry of this star since the proximity point uncertainty is unacceptably large.

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Displacement of the Sun from the Galactic plane

Cited by 97 publications

References 42 publications

Initial phases of massive star formation in high infrared extinction clouds

Initial phases of massive star formation in high infrared extinction clouds

Constraints on Natal Kicks in Galactic Double Neutron Star Systems

On the accuracy of close stellar approaches determination

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