Scientific case


Among variable stars,  $\delta$ Scuti are particularly interesting 
since they can pulsate in different evolutionary phases and are 
characterized by both radial and non-radial pulsation modes. 
The study of pulsational properties of these objects allows to 
obtain independent information on their physical structure and 
evolutionary phase (see e.g. Rodríguez \& Breger 2001, A\&A, 366, 178). 
Even if the majority of $\delta$ Scuti stars are located 
on their Main Sequence (MS)
 or post-MS phases, there are growing evidences in the recent years 
about the presence of $\delta$ Scuti variables among stars which 
are still in their Pre-MS phase (the so called Herbig Ae stars). 
Indeed, there are now at least 13 members or candidate members 
(see e.g. Marconi, Palla \& Ripepi, 2002, Comm. 
in Asteroseismology, 141, 20, Ripepi \& Marconi, "2nd Eddington Workshop", 
Palermo, Italy, 9-11 April, 2003) for this class of variables. 
The study of pulsation in PMS stars is extremely important, since 
the comparison between the observed pulsation modes and the 
prediction from the theory provides a unique means for 
constraining the internal structure of young stars 
(asteroseismological techniques) and for testing 
evolutionary models (Marconi \& Palla 1998, 
ApJL, 507, L141; Suran et al. 2001, A\&A, 372, 233).
However, a fruitful comparison between theory and observations require 
that we unambiguously determine the pulsation frequencies of the 
studied objects. This requirement is in general not easily 
reached because: 1) the pulsation amplitudes are often very small (~ 0.01 
mag or less); 2) the presence of alias frequencies in the periodogram.  
The only way to face the problem 2) is to organize multisite campaigns in 
order to have 24h continuous observations. 
However up to now the sample of PMS $\delta$ Scuti variables 
 observed by means of multisite campaigns includes 
only two objects (see Ripepi et al. 2002 A\&A, 391, 587 for H254 in IC 348 
and Ripepi et al. 2003, A\&A, accepted for the case of V351 Ori).
Of course, it is very important to enlarge this sample. 
To this aim we propose to observe the star IP Per 
in cooperation with other telescope around the world 
(Loiano Telescope, Italy, Teide Observatory, Spain, BAO, 
China, APT, Arizona, USA). 

Info on IP Per

IP Per is a Herbig Ae star of Spectral type A7V and V=10.5; coordinates: 
AR 034057.0 DEC 322759 J(2000). Preliminary 
observations obtained during Dec. 2002 at Loiano telescope allowed to 
determine that this star pulsate as a  $\delta$ Scuti and is multiperiodic 
(amplitude of pulsation  ~<0.01 mag). 
We plan to observe IP Per in at least two filters (in order to try 
to identify the modes). The proposed filters are the Johnson BV but 
also Stromgren by are ok.

The multisite campaign is set for the period Nov, 23-Dec. 7 2003 
(full moon Dec. 8). The object is bright, so I do not think that 
the moon will disturb too much. 
There is a good comparison star at around 11-12 arcmin from IP Per. 

Due to the low amplitudes I do not think that the observations from the 
Philippines will be useful, 
but you are in a better position to judge...