Tag Archive
amateur astronomy awk bash b[e] supergiant cartoon conference convert evolved star exoplanet fedora figaro fits fun galaxy iraf large magellanic cloud latex linux lmc machine learning magellanic clouds massive star matplotlib meteor mypaper paper peblo photometry planet pro-am pyraf python red supergiant scisoft skinakas observatory small magellanic cloud smc spectroscopy starlink talk ubuntu university of crete video x-ray yellow hypergiant
Notes on the density of the disk/rings around B[e] supergiants
In Zickgraf et al. 1989 (A&A, 220, 206) there is a comment on the density of the disk around the supergiant LHA 115-S 18. In Table 1 they provide (following Waters 1986) the mean particle density at r=R* for a number of sources: 3.2 x 1012, 2.6 x 1012, 4.6 x 1012, 1.7 x 1012 cm-3 for sources S 18, S 12, S 134, and R 126, respectively. Having calculated a maximum disk radius of 300R*, they calculate a mean density of few 109 cm-3. These values are consistent with both estimates from IR emission and by McGregor et al. (1988), who independently found densities of about 109 cm-3 from the CO first overtone emission in S 12, S 134, and R 66.
New Paper on BeXRBs – 5 new BeXRBs in the SMC and the link of the supergiant B[e] star LHA 115-S 18 with an X-ray source
Optical spectra of 5 new Be/X-ray Binaries in the Small Magellanic Cloud and the link of the supergiant B[e] star LHA 115-S 18 with an X-ray source
Grigoris Maravelias, Andreas Zezas, Vallia Antoniou, Despoina Hatzidimitriou
The Small Magellanic Cloud (SMC) is well known to harbor a large number of High-Mass X-ray Binaries (HMXBs). The identification of their optical counterparts provides information on the nature of the donor stars and can help to constrain the parameters of these systems and their evolution. We obtained optical spectra for a number of HMXBs identified in previous Chandra and XMM-Newton surveys of the SMC using the AAOmega/2dF fiber-fed spectrograph at the Anglo-Australian Telescope. We find 5 new Be/X-ray binaries (BeXRBs; including a tentative one), by identifying the spectral type of their optical counterparts, and we confirm the spectral classification of an additional 15 known BeXRBs. We compared the spectral types, orbital periods, and eccentricities of the BeXRB populations in the SMC and the Milky Way and we find marginal evidence for difference between the spectral type distributions, but no statistically significant differences for the orbital periods and the eccentricities. Moreover, our search revealed that the well known supergiant B[e] star LHA 115-S 18 (or AzV 154) is associated with the weak X-ray source CXOU J005409.57-724143.5. We provide evidence that the supergiant star LHA 115-S 18 is the optical counterpart of the X-ray source, and we discuss different possibilities of the origin of its low X-ray luminosity (Lx ~ 4 x 10^33 erg/s).
