2 Observations

The high resolution and signal-to-noise spectra obtained are distributed over 30 nights. From May 1996 to May 2000 observations were performed during 17 nights with the Coudé spectrograph at the Brazilian Laboratório Nacional de Astrofísica (Pico dos Dias) (LNA) 1.60 m (B&C) telescope using a EMI CCD camera ( $1152 \times 770$ pixels). For 13 nights, from April 2000 to April 2001, observations were carried out with the fiber-fed extended range optical spectrograph (FEROS) at the ESO - La Silla 1.52m telescope. The LNA spectra were taken with a 1800 $\rm l/mm$ grating (first inverse order) centered on the He  I $\lambda$6678 Å line, with sporadic H$\alpha$ ( $\lambda 6563$ Å) measurements. This arrangement yields a spectral resolution of $R \sim 40~000$ with a reciprocal dispersion of 0.08 Å $/{\rm pixel}$. The signal-to-noise ratio is typically $\sim$250 for exposure times around 300 s. Bias, flat-field and Th-Ar comparison lamp were taken during each night, and observations were reduced with the IRAF package. ESO spectra were taken in a spectral coverage of 3560-9200 Å, recorded in 38 orders on the detector, with typical S/N $\sim 300$ (near He  I 6678 Å). The resolution power of FEROS is $R \sim 48~000$. Spectra studied and shown in this paper are reduced to the heliocentric frame.

The log of spectroscopic observations carried out on HD 127972 is presented in Table 1. A selected sample of He  I 6678 Å line profiles obtained in each observing epoch is shown in Fig. 1. In the present paper we study only lpv associated with NRP. The temporary appearance of emissions in the outer line wings of the He  I 6678 Å line, dimples (Smith & Polidan 1993), central quasi emissions, etc. will be discussed elsewhere.