ترغب بنشر مسار تعليمي؟ اضغط هنا

For the Class 0 protostar, L1527, we compare 131 polarization vectors from SCUPOL/JCMT, SHARP/CSO and TADPOL/CARMA observations with the corresponding model polarization vectors of four ideal-MHD, non-turbulent, cloud core collapse models. These four models differ by their initial magnetic fields before collapse; two initially have aligned fields (strong and weak) and two initially have orthogonal fields (strong and weak) with respect to the rotation axis of the L1527 core. Only the initial weak orthogonal field model produces the observed circumstellar disk within L1527. This is a characteristic of nearly all ideal-MHD, non-turbulent, core collapse models. In this paper we test whether this weak orthogonal model also has the best agreement between its magnetic field structure and that inferred from the polarimetry observations of L1527. We found that this is not the case; based on the polarimetry observations the most favored model of the four is the weak aligned model. However, this model does not produce a circumstellar disk, so our result implies that a non-turbulent, ideal-MHD global collapse model probably does not represent the core collapse that has occurred in L1527. Our study also illustrates the importance of using polarization vectors covering a large area of a cloud core to determine the initial magnetic field orientation before collapse; the inner core magnetic field structure can be highly altered by a collapse and so measurements from this region alone can give unreliable estimates of the initial field configuration before collapse.
72 - Z. Y. Li , S. Qiao , Z. Q. Yang 2010
Spin-orbit splitting in graphene on Ni, Au, or Ag (111) substrates was examined on the basis of density-functional theory. Graphene grown on the three metals was found to have Rashba splitting of a few or several tens of meV. The strong splitting obt ained on Au or Ag substrates was mainly ascribed to effective hybridization of graphene $p_{z}$ state with Au or Ag $d_{z^{2}}$ states, rather than charge transfer as previously proposed. Our work provides theoretical understandings of the metal-induced Rashba effect in graphene.
33 - J. T. Li , Z. Y. Li , Q. D. Wang 2008
We study the edge-on galaxy NGC 5775, utilizing a 58.2 ks {sl Chandra} ACIS-S observation together with complementary {sl HST} ACS, {sl Spitzer} IRAC and other multi-wavelength data sets. This edge-on galaxy, with its disk-wide active star formation, is particularly well-suited for studying the disk/halo interaction on sub-galactic scales. We detect 27 discrete X-ray sources within the $D_{25}$ region of the galaxy, including an ultra-luminous source with a 0.3-7 keV luminosity of $sim7times10^{40}rm ergs s^{-1}$. The source-removed diffuse X-ray emission shows several prominent extraplanar features, including a $sim10rm kpc$ diameter ``shell-like feature and a ``blob reaching a projected distance of $sim25rm kpc$ from the galactic disk. The bulk of the X-ray emission in the halo has a scale height of $sim$1.5 kpc and can be characterized by a two-temperature optically thin thermal plasma with temperatures of $sim$ 0.2 and 0.6 keV and a total 0.3-2 keV luminosity of $sim3.5times10^{39}rm ergs s^{-1}$. The high-resolution, multi-wavelength data reveal the presence of several extraplanar features around the disk, which appear to be associated with the in-disk star formation. We suggest that hot gas produced with different levels of mass loading can have different temperatures, which may explain the characteristic temperatures of hot gas in the halo. We have obtained a sub-galactic scale X-ray-intensity-star formation relation, which is consistent with the integrated version in other star forming galaxies.
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا