Background information on ULDA spectra of TTS


The Herbig and Bell (1988) Catalogue (HBC) contains 742 PMS stars and is the most complete and up-to-date compilation of young stars. All the stars in this catalogue that have been observed with IUE are included in our catalog. All the sources classified in the Data Base as TTS (class 58) are in the HBC catalogue. A complete list can be found in Appendix A together with some general information as the 1950.0 ecuatorial coordinates, the V apparent magnitude and its range of variability as in the HBC, the molecular cloud to which the star is associated and the number of low dispersion spectra obtained with IUE in the LWP, LWR and SWP cameras.

In order to facilitate work with this catalogue we provide for each source a list of general information on physical properties and the spectral energy distribution. This is followed by a list of details on the available IUE observations and some basic data derived from them. This information is completed with two figures: the mean spectrum of the star and the light curve as derived from FES measurements.


A list of general information:



This is homogeneous object identification as established in the IUE Data Bank (Barylak, 1991). Also the variable star name is provided.

Other identifications

The HBC entry number as well as other conventional designations provided in the HBC.


Indicates to which group the star belongs. The classification has been taken after the HBC. The abreviations are: CTTS, WTTS, SUAur and FUOri. CTTS holds for Classical TTSs, WTTS for weak line TTSs, SUAur for stars like SU Aur (type late F to K, weak emission in Halpha and Ca II, very broad absorption lines (vsini > 50 km/s) and relatively high luminosity) and FUOri for stars like FU Ori (DEFINICION HBC).

Spectral type

After HBC.

Photometric data

UBVRI values have been extracted from the HBC. Therefore the data are not homogeneous and include Johnsons-Cousins, Johnson (marked with *) and Instrumental (marked with *i). The conversion factors are given in Rydgren et al...???. These data have been completed with published values when they are more complete than the quoted in the HBC. The source reference is indicated in the table. JHK photometric data have been extracted from Vrba et al (1986) for the stars in Taurus and from the Catalog of Infrared Observations (Ref.).

IRAS fluxes

Most of them have been taken from Weaver & Jones (1992). The flags a, b and c hold for the estimated errors, δF: a (δF ≤ 10%), b (10 % ≥ δF ≤ 25 %) and c (δF ≥ 25 %). For the rest of the sources the reference from which the IRAS fluxes have been taken is indicated in the table.

Activity parameters

Photometric period, amplitude of the brightness variations in the V band, rotational velocity as in the HBC completed with the results of the last monitoring campaigns. Einstein and ROSAT X-rays fluxes are also provided when available. The precise references are indicated in the table.

Wind parameters

Hα and [O I] equivalent widths. W(Hα) has been taken from the HBC. For the W([OI]) values the references are given. The association with optical jets and HH objects has been obtained by a comparison with the ”General Catalogue of Herbig-Haro objects” (Reipurth 1994).


Characteristics of the system (double, triple...) and the separation between the components. For the TTS that are known to be spectroscopic binaries the period is indicated. Also TTS whose binarity has been searched for and not found are indicated. The precise references are indicated in the table.


A list with IUE observations

The log of the IUE observations is provided. For each observation we indicate, the camera and image number, the dispersion, 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 FES magnitude is provided in the last column. The images are ordered by camera and date of observation.


A list with basic data derived from the IUE observations

A table with the mean fluxes of the most prominent UV lines (CIV, Si IV, Si II, C III, C II] and Mg II) and the mean continuum flux in two windows of 50 Angstroms centered at 1855 Angstroms and 2900 Angstroms that have been proved to be well suited for measuring the continuum level (Gómez de Castro & Fernández 1996).



The first figure is a plot with the mean UV spectrum of the stars. The Mg II high resolution profiles are also displaied when available. The second figure is the FES light curve and it is only represented for stars with several IUE observations. Additional, larger scale, plots are made when there are 3 or more observations separated by time lapses smaller than the photometric period.