A JET FROM A VERY LOW MASS STAR (M5 V)
M. Fernandez
and F.MASS
Comeron
A JET FROM
A VERY LOW
STAR (M5 V)
Instituto de Astrofisica de Andalucia, CSIC, Spain
M. Fernandez
and F.Observatory
Comeron
European
Southern
Instituto de Astrofisica de Andalucia, CSIC, Spain
European Southern Observatory
Jets can be considered an universal and efficient mechanism of
loosing angular momentum, when matter from a disk falls onto a
central object. Sizes range from galactic to stellar scales. In the last
years, evidence has been found that the mass accretion model that
applies to all these objects can be traced down to the substellar limit
(Fernandez & Comeron, 2001; Muzerolle et al., 2003; Barrado y
Navascues et al., 2004). Here we present evidences of a jet
emanating from a young M5 star: Par Lup3-4.
Parallactic angle: 33
Figure 1
Par Lup3-4 was discovered in the course of an Hα survey carried out
in the Lupus 3 region (Comeron et al., 2003). Its strong emission at
permitted and forbidden lines indicates a strong mass accretion
process and makes it a promising candidate for the search of jets or
outflows (see Figure 1).
Multi-run observations were carried out on Par Lup3-4 at the
VLT (Paranal, Chile) during June and July 2003 in service mode
(71.C-0429C). Narrow band [SII] and Hα images were taken
using FORS, and high-resolution spectroscopy was carried out
along 5 nights from July 3 to July 29 using the UVES echelle
spectrograph. In order to avoid light loss due to atmospheric
refraction, the slit position angle tracked the parallactic angle
during the observation. Since data have been acquired at
different times, the slit position angle differs from one spectrum
to another.
Figure 2
Parallactic angle: −54 Parallactic angle: 84
Figure 2 shows three of the spectrograms obtained for Par Lup34. The first of them shows strong [SII] emission lines, as they
would be expected from a point source. The spectra of the other
two nights, on the other side, show emission originating from the
surroundings of the star. The emission comes from opposite sides
on each of these two nights, but this is just an effect of the
different position angle of the slit and they both come, spatially,
from the same side of the star. The observed emission extends up
to 2" from the star.
Figure 3
Some of the reduced spectra are shown in Figure 3. The variability observed at the [SII] lines is attributed
to the changes of the position angle of the slit, while for Hα it might be related to the mass accretion
process.
Figure 4 is the composition of a narrow band [SII] image (red) and an Hα image (blue) of Par Lup3-4.
The extended emission is clearly detected at the [SII] lines, while the H alpha image shows no hints of
such extended emission. To our knowledge, this is the less massive object which has been discovered to
excite a jet.
References
D.Barrado y Navascues, S.Mohanty and R.Jayawardhana 2004 ApJ 604, 284
F.Comeron, M.Fernandez, I.Baraffe, R.Neuhaeuser and A.A.Kaas 2003 A&A 406, 1001
M.Fernandez and F.Comeron 2001 A&A 380, 264
Muzerolle, L.Hillenbrand, N.Calvet, C.Briceno and L.Hartmann 2003 Apj 592, 266
Figure 4