OUTLINE
X-RAY EMISSION PROCESSES (pages 7-8)
Basic references for X-ray plasma spectroscopy
- Chianti-an atomic database for emission lines. VI Young et al. ApJS 144, 135 (2003).
- Previous papers in the series by Dere et al. begin with A+AS 125, 149 (1997).
- Chianti includes a list of atomic energy levels, wavelengths, radiative transition probabilities, and electron excitation data for a wide range of ionization states (e.g., Fe II-XXVI) (see tables 1 and 2 of Paper VI). This software allows one to compute synthetic spectra including X-ray and EUV emission lines (1-1150 A) and continua (bound-free, free-free, and two-photon) (see Figure 6 of Paper VI) for specified temperatures and electron densities.
- Chianti computes population of atomic energy levels in statistical equilibrium (no time variations) including collisional excitation and de-excitation by a Maxwell-Boltzmann distribution of electron (and proton) energies, photoexcitation, photoionization, radiative recombination and de-excitation.
- Note that the continuum dominates over line emission for hot plasmas (log T > 7.2) characteristic of active star coronae and flares, whereas the lines dominate the continuum for warm plasmas (log T < 6.5) characteristic of the solar corona and inactive stars (old slow-ratating stars).
- Two-photon continuum is the radiative decay from the first excited level of hydrogen-like ions (e.g., Fe XXVI) and the second excited level of helium-like ions (e.g., Fe XXV), which are metastable.
- The Chianti series papers and database and software packages (in IDL) are available. Go to Chianti homepage.
- To compute an ascii file of spectral line intensities and wavelengths use ASCII_WVL_DEM (an IDL proceedure).
- Astrophysical Plasma Emission Database (APED). Atomic data, abundances, and ionization balance data. APED includes Chianti and other databases.
- Package for Interactive Analysis of Line Emission (PINTofALE). This is a downloadable package of IDL routines for the analysis of X-ray spectral data. PINTofALE will identify spectral features, measure line fluxes, and allow the user to do detailed modelling. Also see description of PINTofALE in PINTofALE Description.
CHANDRA X-RAY OBSERVATORY (pages 1-4)
- Website for Chandra general information
- Website for Chandra science website
- Website for Chandra data archive
- Next deadline for proposals is 12 March 2004.
- Website for XMM-Newton general information
- Website for XMM-Newton science website
- Website for XMM-Newton data archive
- Next deadline for proposals is 8 October 2004.
High Energy Astrophysics Science Archive Research Center (HEASARC)
- The HEASARC is an excellent place to find information and download data from all X-ray observatories. Very useful for browsing data in all X-ray archives.
- Click on "Browse" to browse observations of specified targets and download data (in FITS format).
- The only all-sky survey in soft X-rays now available is the ROSAT All-sky Survey. For a description of the RASS see Voges et al. A+A 349, 389 (1999).
STELLAR CORONAE
- A review paper on stellar coronae
- Close binary systems (RS CVn systems, W UMa systems, Algols)
- Multiwavelength observations of HR 1099 (K1 IV + G5 IV)and Capella (G1 III + G8 III) (X-ray spectra in figure 4.)
- Helium-like triplet density diagnostics The helium-like triplet lines of C V, N VI, O VII, Ne IX, Mg XI, Si XIII may be useful diagnostics of coronal densities using the forbidden/intersystem line ratio.
- M dwarfs and brown dwarfs
- Chandra and XMM-Newton observations of YY Gem M0 V + M0 V) See figure 3 for the Chandra LETGS and XMM-Newton RGS spectra and figure 5 for the helium-like triplet lines.
- Solar type stars
- Chandra and XMM-Newton observations of Procyon (F5 IV-V) See figures 1 and 2 for the Chandra LETGS and XMM-Newton RGS spectra of this solar-like inactive star with a cool corona.
- Hot stars
- Hot stellar wind of Theta1 Orionis See figure 2 for the X-ray spectrum of this O6pe star with a hot (60,000,000 K) wind with velocity up to 2000 km/s.
- Stars without coronae
- Buried alive in the coronal graveyard Very low upper limits on the X-ray luminosity from Arcturus (K2 III) and Aldebaran (K5 III). See figure 2 for a comparison of the X-ray and UV luminosities of other stars and figure 5 for an unconventional model.
YOUNG CLUSTERS, PREMAIN SEQUENCE STARS, AND THE YOUNG SUN
- High-energy processes in young stellar objects (pre-Chandra) (Feigelson and Montmerle ARAA 37, 363 (1999)) is an excellent review paper (although Chandra has taken the field much further).
- Stages of stellar evolution (figure 1).
- Magnetic field configurations (figure 2 and 3).
- ASCA spectra of hot Class 0-1 stars compared to Class III stars (figure 6).
- Magnetic field reconnection event model (figure 7).
- Chandra/ACIS-I study of the Orion Nebula Cluster (Feigelson et al. ApJ, 584, 911 (2003)).
A total of 1075 X-ray sources of which 525 have estimated ages and masses.
Orion Cluster at 500 pc.
- Pre-Chandra knowledge of soft X-ray emission vs. rotation for main sequence solar-type stars.
- Pre-Chandra knowledge of soft X-ray emission vs. Rossby number for open clusters and field stars.
Rossby number = P/tau_c = rotation period/convective turnover time.
The Rossby number is an important parameter in some dynamo models.
Note saturation and supersaturation.- X-ray properties of ONC stars
- L_x vs L_{bol} for ONC stars. Large scatter may be due to flaring.
- L_x/L_{bol} vs volume for ONC stars. L_x ~ R^2.
- L_x/L_{bol} vs mass for ONC stars. High-mass and low-mass stars have similar X-ray properties.
- Lx/L_{bol} vs presence or absence of a disk
The disk does not play a role in the X-ray emission at least for young stars.
Accretion may explain X-ray emission in older (5My) CTTS like TW Hya.- L_x/L_{bol} vs stellar age.
Why the rise in L_x/L_{bol} for the older stars? Possibly due to decrease in radius and conservation of angular momentum as stars approach the main sequence.
PROBLEMS FOR THE STUDENTS
