Background information on IUE spectra of TTS

The Reipurth (1997) Catalogue (RC) contains about four hundreds of Herbig-Haro (HH) objects and is the most complete and up-to-date compilation; only 19 of them were observed with the IUE. A complete list can be found at the end of this introductory section, together with some general information as the 1950.0 ecuatorial coordinates, the exciting star, the molecular cloud to which the star is associated, the excitation characteristics of the HH object (high excitation object:HEO or low excitation object:LEO), and the number of low dispersion spectra obtained with the LWP, LWR and SWP cameras.

In order to faccilitate work with this catalogue we provide for each HHO a list of general information followed by a list with the available IUE observations. Then we describe in detail the IUE observations classified by subsets obtained at the same location on the nebulosity (same center and Position Angle (P.A.) of the IUE large aperture). For each subset, we include a figure indicating the precise location of the IUE slit on an optical image of the HHO (typically obtained with a narrow band filter centered at the [S II] lines). Then a table with integrated line fluxes measured on the extracted spectrum is provided. Finally for each IUE image, the extracted spectrum as well as the resampled image (SILO file) are displayed

Name

Other identifications

Type

Coordinates

Proper motion

Radial velocity

Suspected source

Region

Distance

Characteristic size

Associated with molecular outflow

P.A. of the jet

The log of the IUE observations is provided. For each observation we indicate, the camera and image number, the dispersion, the aperture, the date of observation, the integration time and the quality given by the observer according to standard codes adopted for the description of the IUE images. The P.A. of the IUE large slit in the plane of the sky is also indicated.

A key map

This is a contours (isophotes) map of the nebulosity on top of which we have plotted the IUE Large Aperture (LAP). The contours map has been scanned from the publication indicated at the bottom of the figure; in most objects the images have been obtained with a narrow band filter centered at the optical forbidden lines of [S II] (centered at λλ 6717,6731 Å). All the maps in this catalog have the same spatial scale: the field is ~ 40′′× 40′′ and the separation between two small tickmarks is 2”. The lenght of the LAP on the map is ~ 22”; in practice, there is a small difference of ~ 1” between the projected size of the LAP in the LWP and SWP cameras. A small mark has been drawn on the border of the aperture to indicate the P.A. (removes the ±180o uncertainty); this information is relevant to interpret the resampled image (see below).

A list with basic data derived from the IUE observations

A table with the mean fluxes of the most prominent UV lines (Mg II (UV1), C II]2330, C III]1909 and C IV (UV1)) is provided. No attemp has been carried out to measure the strength of the fluorescent H2 lines which are usually strong in low excitation objects. Neither we have tried to measure the strength of the continuum although it is strong in some sources.

The line fluxes have been measured directly on the extracted spectrum and no special procedures, as those applied by Cameron & Liseau (1990) or Liseau et al (1996), have been used. Therefore, they do only provide an overall idea of the UV spectral characteristics of the objects.

Spectra

Two figures are represented per IUE image: the extracted spectrum at the top and the resampled image at the bottom. Only spectra where actual emission has been detected are displayed. The extracted spectrum displayed is the produced by NEWSIPS (SWET extraction procedure); flagged pixels (see the NEWSIPS manual) are marked with asterisks. The resampled image (SILO file) contains all the spatial information since it is a primary array produced by resampling the photometrically corrected portion of the image using the modified Shepard algorithm taken from the Numerical Algorithms Group (NAG) software package (see NEWSIPS manual). The gray scale is coded so the larger the flux the darker the gray level. The white points represent the location of the reseau marks. The location of the IUE large and small apertures is clearly seen in the SWP images due to the geocoronal Lyα emission. The coordinate along the y-axis is the distance from the center of the LAP (in arcsec). We have assign positive values to increasing distances from the center towards the P.A. (tickmark on the LAP of the “key map”) and negative values to increasing distances from the center towards P.A.±180o.

The spatial structure of the HHOs UV emission is resolved along the LAP for some objects. The spatial resolution of the IUE along the LAP is similar for the LWP and LWR cameras; the best is near 3000 Å and decreases shortwards: at 3000 Å, the spatial resolution is ~ 2.4 pixels (3.”6) and 2.6 pixels (3.”9) in the LWP and LWR cameras respectively, while at 2000 Å the spatial resolution is ~ 3.0 pixels for both cameras. The SWP camera spatial resolution is nearly constant from 1200 to 1400 Å (~2.7 pixels or 4.”1) and decreases to 3.7 pixels at 1950 Å(see the NEWSIPS manual for more details).