Context. GR 290 (M 33/V532 = Romano’s Star) is a suspected post-luminous blue variable star located in M 33 galaxy that shows a rare Wolf–Rayet (WR) spectrum during its minimum light phase. In spite of many studies, its atmospheric structure, its circumstellar environment, and its place in the general context of massive stars’ evolution is poorly known. Aims. We present a detailed study of this star’s wind and mass loss, and a study of the circumstellar environment associated to the star. Methods. Long-slit spectra of GR 290 were obtained during its present minimum luminosity phase with the Gran Telescopio Canarias covering the ∼3600–7500 Å wavelength range together with contemporaneous photometry using B, V, R and I filters. The data were compared with non-local thermodynamical equilibrium (non-LTE) model atmosphere synthetic spectra computed with CMFGEN code and with models for ionized interstellar medium regions computed with CLOUDY code. Results. The current m_V = 18.8 mag is the faintest at which this source has ever been observed. The non-LTE models indicate effective temperatures of T_eff = 27 000–30 000 K at radius R_2/3 = 27−21 R_⊙ and mass-loss rate Ṁ = 1.5 × 10⁻⁵ M_⊙yr⁻¹. The terminal wind speed v_∞ = 620 km s⁻¹ is faster than ever before recorded, while the current luminosity L_* = (3.1–3.7) × 10⁵L_⊙ is the lowest ever deduced. The star is overabundant in He and N and underabundant in C and O. It is surrounded by an unresolved compact H II region with dimensions ≤4 pc, from where H-Balmer, He I lines, and [O III] and [N II] are detected. In addition, we find emission from a more extended interstellar medium (ISM) region, which appears to be asymmetric, with a larger extent to the east (16–40 pc) than to the west. Conclusions. In the present long lasting visual minimum, GR 290 is in a lower bolometric luminosity state with higher mass-loss rate. The nearby nebular emission seems to suggest that the star has undergone significant mass loss over the past 10⁴–10⁵ yr and is nearing the end stages of its evolution.

The realization of low-cost instruments with high technical performance is a goal that deserves efforts in an epoch of fast technological developments. Such instruments can be easily reproduced and therefore allow new research programs to be opened in several observatories. We realized a fast optical photometer based on the SiPM (Silicon Photo Multiplier) technology, using commercially available modules. Using low-cost components, we developed a custom electronic chain to extract the signal produced by a commercial MPPC (Multi Pixel Photon Counter) module produced by Hamamatsu Photonics to obtain sub-millisecond sampling of the light curve of astronomical sources (typically pulsars). We built a compact mechanical interface to mount the MPPC at the focal plane of the TNG (Telescopio Nazionale Galileo), using the space available for the slits of the LRS (Low Resolution Spectrograph). On February 2014 we observed the Crab pulsar with the TNG with our prototype photometer, deriving its period and the shape of its light curve, in very good agreement with the results obtained in the past with other much more expensive instruments. After the successful run at the telescope we describe here the lessons learned and the ideas that burst to optimize this instrument and make it more versatile. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Objects with the B[e] phenomenon, whose defining features are the presence of forbidden emission lines and infrared excess coming from circumstellar dust, represent a broad range of evolutionary stages from pre-main-sequence to planetary nebulae. They are important for understanding mechanisms of the circumstellar matter formation and evolution. However, it is not easy to discover them, especially among faint stars, as forbidden emission lines are usually weak and hardly noticeable in low-resolution spectra. We developed photometric criteria to search for candidate objects with this phenomenon based on a combination of optical and near-infrared color indices and found nearly 40 objects that satisfy these criteria. Spectroscopy of the candidates allows us to make more confident conclusions on their classification. We present the results of our photometric and spectroscopic observations of six objects, which are part of a large list of ∼40 objects that satisfy our photometric selection criteria for candidate objects with the B[e] phenomenon. Forbidden lines of neutral oxygen were clearly detected in the optical spectrum of one object (VES 683) and suspected in three others. One object, AS 415, is most likely a binary system with components that exhibit partial eclipses but without the B[e] phenomenon, while IRAS 20402 + 4638 may be a luminous member of the FS CMa objects group.