Archive for March, 2018

Mixing a transient object with … Mars!

Posted March 22, 2018 By grigoris

In the Astronomer’s Telegram #11448 [1] it is announced that a very bright (almost 1st magnitude) transient object is found between the Lagoon and the Trifid nebulae. No other object has been found in the region and the source itself was not visible some days earlier.

Within less than an hour later a second follow up telegram (#11449) informs the community that the transient object is … Mars !

It goes without saying that errors are for humans. But this one shows that every astronomer has to have a basic grasp of the night sky at least.

[1] http://www.astronomerstelegram.org/?read=11448
[2] http://www.astronomerstelegram.org/?read=11449

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Seminar talk at NOA

Posted March 19, 2018 By grigoris

As I am waiting my flight to Heraklion, I thought that I should post the talk that I gave earlier today at the National Observatory of Athens, Greece:

“B[e] Supergiants: a missing part from the massive star puzzle?”

Abstract:
Massive stars affect strongly the insterstellar medium through their intense stellar winds and their rich chemically processed material as they evolve. This interaction becomes substantial in short-lived transition phases of massive stars (e.g. B[e] Supergiants, Luminous Blue Variables, Yellow Hypergiants) in which mass-loss is more enhanced and usually eruptive. Consequently, a complex environment, combining atomic, molecular and dust regions is formed around these stars. In particular, the circumstellar environment of B[e] Supergiants is not well understood. Moreover, their possible link to other phases has not been fully uncovered yet, which is crucial given the importance of massive stars for Stellar Astrophysics and their influence on their host galaxies. Starting from an observational point of view, I will provide an overview of the B[e] Supergiant population and discuss the latest results.

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Proposal brainstorming …

Posted March 14, 2018 By grigoris

From our previous meeting.

Putting ideas on the chalkboard (Image © Paul Sell, CC BY-SA-ND).

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IRAF’s identify error – center not found

Posted March 9, 2018 By grigoris

During the last few days I have struggled a bit with the wavelength calibration of some long-slit spectra. When using the identify task of IRAF I found that I could select (“m”ark) only some of the lines, without any clear indication why the rest were not recognized (some were indeed stronger but others were equal or weaker). The actual error that kept popping out was “Center not found: check cursor position”. Although I went on to investigate all parameters (even the aidpars !) the one thing that solved the problem was finally to increase a bit the full-width of the features to be identified (fwidth), from the default value of 4.0 to 10 pixels. Apparently some of the lines seems too wide to be determined as real features by the task.

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New position at FORTH and UoC

Posted March 2, 2018 By grigoris

Since October 2017 I have been affiliated with the Department of Physics at the University of Crete, but last week I started working officially as a post-doc with Andreas Zezas. The position is directly affiliated with the Foundation for Research and Technology – Hellas (FORTH), and in particular with the Institute of Electronic Structure and Lasers (IESL).

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A new Institute for Astronomy in Crete

Posted March 2, 2018 By grigoris

Finally after many years of delays and unfortunate events a new institute focusing solely in Astronomy is founded as part of the Foundation for Research and Technology – Hellas (FORTH). This is the successful outcome of a continuous effort by the very active astronomy group at the University of Crete. Congratulations to the group and we anticipate the future achievements!

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