Archive for July, 2018

Building an observatory in Syria

Posted July 10, 2018 By grigoris

At the last issue of CAP journal (No. 23, Feb 2018) we find the article “The World at a Glance: Highlights from IAU National Outreach Contacts” that provides short news from the IAU National Outreach Contacts. And for Syria we read:

“Mohamad AlAssiry: Despite the political situation, the Syrian Astronomical Association was building an observatory and opened in August 2017.”

which I found impressive given the country’s situation since the war broke out in 2011.

Of course, a counter-argument would criticize the prioritization given the number of lives threaten everyday in Syria. However, only education and civilization will help us overcome (on the long-term unfortunately…) these problems.

Finally, after some years of work, it has been accepted for publication in MNRAS.

Resolving the kinematics of the disks around Galactic B[e] supergiants

Grigoris Maravelias, Michaela Kraus, Lydia S. Cidale, Marcelo Borges Fernandes, Maria L. Arias, Michel Curé, Georgios Vasilopoulos

B[e] Supergiants are luminous evolved massive stars. The mass-loss during this phase creates a complex circumstellar environment with atomic, molecular, and dusty regions usually found in rings or disk-like structures. For a better comprehension of the mechanisms behind the formation of these rings, detailed knowledge about their structure and dynamics is essential. To address that, we obtained high-resolution optical and near-infrared spectra for 8 selected Galactic B[e] Supergiants, for which CO emission has been detected. Assuming Keplerian rotation for the disk, we combine the kinematics obtained from the CO bands in the near-IR with those obtained by fitting the forbidden emission [OI] λ5577, [OI] λλ6300,6363, and [CaII] λλ7291,7323 lines in the optical to probe the disk structure. We find that the emission originates from multiple ring structures around all B[e] Supergiants, with each one of them displaying a unique combination of rings regardless of whether the object is part of a binary system. The confirmed binaries display spectroscopic variations of their line intensities and profiles as well as photometric variability, whereas the ring structures around the single stars are stable. 1807.00796

Figure 12 from the paper: A cartoon illustration of the disk-structures as derived from our analysis. We represent the [OI] λ5577 line as *[OI]*, the [OI] λλ6300, 6363 doublet as [OI], and the [CaII] λλ7291, 7323 as [CaII]. The arrows above the rings symbolize the typical ring-widths and are given in km/s. (For more details on the data used and references see Table 3. Note that the relative structures and sizes are not in scale.