SIMBAD references

In an effort to determine the orbital period of the enigmatic star DI Cru (HD 104994, WR 46), we made photometric and spectroscopic observations of this object between 1996 and 2002. Both photometric and spectroscopic characteristics are quite complex. The star is highly variable on short (few hour) as well as on long (few month) timescales. The optical spectrum is rich in strong emission lines of high-ionization species such as He II, N IV, N V, and O VI. Weak emission of C III is also present. Emission lines have been compiled and identified from the ultraviolet to the infrared. In the UV, emission of O V and N IV is also observed, together with very weak emission of C IV. The N V λλ4603, 4619/He II λ4686 line ratios vary by a significant amount from night to night. Temporal variance spectrum analysis shows that the He II λ4686 line has P Cyg-like variable absorption, while N V λλ4603, 4619 lines have a strong and broad variable component due to the continuum fluorescence from a source (stellar atmosphere/optically thick wind) of variable temperature. We also show that the object has variable degree of ionization, probably caused by wind density variation. The star presents multiple periods in radial velocity and photometry. From our data we derived a main radial velocity period of 0.3319 days with an amplitude of K=58 km/s. This period is similar to the value found by Marchenko and coworkers. When at intermediate brightness, this period is also seen in the photometric measurements. When the star is at bright phase, the photometric variations do not present the same period. Photometric periods ranging from 0.154 to 0.378 days are present, consistent with observations reported by other authors. Besides the 0.3319 day period, other spectroscopic periods are also seen. On distinct epochs, the periods are different; Marchenko et al. interpreted the 0.3319 day period as the orbital one. Although we do not discard this possibility, the true binary nature (e.g., long-term coherence or detection of a secondary star) has not yet been demonstrated. DI Cru is a Population I WR object. Given the similarities (e.g., multiple periods likely due to nonradial oscillations), it could be interpreted as a luminous counterpart of the qWR star HD 45166.