J/A+A/680/A81 Halpha datacubes of the Carina arm tangency (Russeil+, 2023)
A deep Hα survey of the Carina tangent arm direction.
Russeil D., Zavagno A., Amram P., Elia D., Molinari S., Lecoarer E.
<Astron. Astrophys. 680, A81 (2023)>
=2023A&A...680A..81R 2023A&A...680A..81R (SIMBAD/NED BibCode)
ADC_Keywords: H II regions ; Photometry, H-alpha
Keywords: stars: kinematics and dynamics - HII regions
Abstract:
The arm tangent direction provides a unique viewing geometry, with a
long path in relatively narrow velocity ranges and lines of view that
cross the arm perpendicular to its thickness. The spiral arm tangent
regions are therefore the best directions for studying the
interstellar medium within spiral density waves in the Milky Way,
probing the internal structure in the arms. We focus here on the gas
kinematics and star formation in the Galactic plane zone with
longitudes of between 281° and 285.5° and latitudes of between
~-2.5° and ∼1°, respectively, which contains the Carina arm
tangency.
The Carina arm tangent direction was observed as part of a
velocity-resolved Hα survey of the southern Milky Way using a
scanning Fabry-Perot mounted on a telescope, which makes it possible
to obtain data cubes containing kinematic information. Our detailed
analysis of the resultant Hα profiles reveals the presence of
several layers of ionized gas with different velocities over the
surveyed region. We combine the Hα data with multi-wavelength
information in order to assign velocity and distance to the HII
regions in the probed area and to study the star-formation activity in
the Carina arm tangency.
We find that the Carina arm tangency is at l=282°, and that it
spreads from 2 to 6kpc with a VLSR range of between -20 and +20km/s.
We deduce an arm width of ∼236pc. We also probe the star formation on
a scale of ∼1kpc-2, showing that the star-formation activity is
intermediate in comparison with the quiescient Solar neighborhood and
the most active Galactic central molecular zone. From our analysis of
the stellar motions extracted from the Gaia DR3 catalog, we observe
that stars around 2.5kpc are tracing the trailing and the leading
sides of the arm, while stars at greater distances more closely trace
the inner part of the arm. In parallel, we studied the Hα
velocity structure of the HII regions RCW48 and RCW49 in detail,
confirming the expansion velocity of ∼20km/s for RCW 49 and the
double-shell structure of RCW 48, which is in agreement with a wind
interaction with a previous mass-loss episode.
Description:
We analyze the Hα emission of a region centered toward the
Carina tangent arm direction with the aim to precise/determine the
nature and the kinematics of the HII regions and the diffuse Halpha
emission.
The FITS files contain the data cubes corresponding to the optical
Halpha line, covering the Carina arm tangency. They were taken between
1992 and 1994, using a scanning Fabry-Perot interferometer mounted on
a 36cm telescope located at La Silla-ESO.
The velocity are Vlsr velocities in m/s.
In some field we can note annular-like feature. These artifacts are
reflections of bright stars in the field and are located at a
symmetrical position of a bright star relative to the center of the
Perot-Fabry rings.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 97 25 List of fits datacubes
fits/* . 25 Individual fits datacubes
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 F4.2 arcsec/pix Scale Scale of the image
25- 27 I3 --- Nx Number of pixels along X-axis
29- 31 I3 --- Ny Number of pixels along Y-axis
33- 34 I2 --- Nz Number of slices
36- 39 I4 --- PF Perot-Fabry interference order
41- 49 F9.4 km/s bVlsr Lower value of velocity interval
51- 58 F8.4 km/s BVlsr Upper value of velocity interval
60- 67 F8.5 km/s dVlsr Velocity resolution
69- 77 E9.4 Hz Freq Line rest frequency
79- 82 I4 Kibyte size Size of the FITS file
84- 97 A14 --- FileName Name of the FITS file in subdirectory fits
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Acknowledgements:
Delphine Russeil, delphine.russeil(at)lam.fr
(End) Delphine Russeil [LAM, France], Patricia Vannier [CDS] 07-Oct-2023