J/A+A/416/655 Atomic lines in IR spectra for ultracool dwarfs (Lyubchik+, 2004)
Atomic lines in infrared spectra for ultracool dwarfs Lyubchik Y., Jones H.R.A., Pavlenko Y.V, Viti S., Pickering J.C., Blackwell-Whitehead R. <Astron. Astrophys. 416, 655 (2004)> =2004A&A...416..655L
ADC_Keywords: Stars, dwarfs ; Spectra, infrared ; Atomic physics Keywords: infrared: stars - stars: low mass - brown dwarfs - atomic data Abstract: We provide a set of atomic lines which are suitable for the description of ultracool dwarf spectra from 10000 to 25000Å. This atomic linelist was made using both synthetic spectra calculations and existing atlases of infrared spectra of Arcturus and Sunspot umbra. We present plots which show the comparison of synthetic spectra and observed Arcturus and Sunspot umbral spectra for all atomic lines likely to be observable in high resolution infrared spectra. Description: Table 1 contains all identified lines with central intensities deeper than 0.8 of residual flux using "ultracool dwarf model" identifications. Table 2 investigates the sensitivity of priority 1 lines identified in Table 1 to temperature, gravity and metallicity. We compute some synthetic spectra for ultracool objects varying parameters of Teff, log g and metallicity to show the sensitivity of the central intensities of identified lines to these parameters. For our computations we chose the minimal step in model atmospheres grid: ΔTeff=100K, Δlogg=0.5, Δ[M/H]=-0.5. STeff shows the dependence of residual fluxes on effective temperature. For comparison a 2100/5.0/0.0 synthetic spectrum was used. One can see that only a few lines show strong temperature dependence for Δ=100K. The NextGen 2000/4.5/0.0 model was used with 2000/5.0/0.0 to test gravity sensitivity. The dependence for Δ(log g)=0.5 is also relatively weak for most lines. The NextGen model atmospheres 2000/5.0/-0.5 and 2000/5.0/0.0 to test metallicity sensitivity. The metallicity dependence is relatively high for all lines. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 51 198 Atomic lines found in ultracool dwarf synthetic spectrum from 1-2.5um table2.dat 46 51 Sensitivity of first priority lines to temperature, gravity and metallicity. tables.tex 127 418 LaTeX version of the tables
See also: J/ApJS/103/235 : Arcturus IR spectral atlas (Wallace+ 1996) J/PASP/107/1042 : Infrared Arcturus Atlas (Hinkle+ 1995) J/AJ/126/1526 : IR photometry of ultracool dwarfs (Bouy+, 2003) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1 I1 --- Pr ? Priority of the line for measurement of atomic data (1) 3 A1 --- n_Ion [*] Note on measurements (2) 4- 12 F9.3 0.1nm lambda Wavelength of the line in air (3) 15- 18 A4 --- Ion Element name with ionization stage 21- 25 F5.3 --- UCDss Residual flux (F(line)/F(cont.)) in "ultracool dwarf" synthetic spectrum 28- 32 F5.3 --- Arss Residual flux (F(line)/F(cont.)) in "Arcturus-like" synthetic spectrum 34 A1 --- l_ArAt [~] Limit flag on ArAt (4) 35- 38 F4.2 --- ArAt ? Residual line intensity from hard copy of Arcturus atlas (accuracy 0.01-0.02) (6) 39- 40 A2 --- n_ArAt [bl T] Note on ArAt (5) 43 A1 --- l_SsAt [~] Limit flag on SsAt (4) 44- 47 F4.2 --- SsAt ? Residual line intensity from hard copy of Sunspot umbra atlas (accuracy 0.02-0.03) (5) 48- 49 A2 --- n_SsAt [bl T] Note on SsAt (5)
Note (1): Priority of lines for measurement of atomic data: Priority 1 indicates that atomic line is deeper than 0.6 in the 2000/5.0/0.0 synthetic spectrum. Also we include as first priority three lines of Ti (22211.229, 22232.838, 22274.012Å) which are shallower than 0.6. They are located far from strong atomic and molecular lines and thus are good for identification purposes in the spectra of ultracool dwarfs. Priority 2 indicates that the residual flux of an atomic line is between 0.8- 0.6. Priority 3 indicates that the atomic line is located in the wing of a nearby stronger line or in a wavelength region with strong telluric absorption. Atomic lines without an assigned priority might be relevant in the analysis of ultracool dwarf spectra, but they are predicted to be weak in the synthetic spectrum. Note (2): An * indicates atomic lines of Rb, Y, Ba and Lu, identified only using theoretical computations. Although these lines are not seen in the observations of Arcturus and Sunspot umbra, they are strong in synthetic spectrum computed for the 2000/5.0/0.0 model atmosphere, and therefore also likely to be strong below 2000K. Note (3): These values were taken fromVienna Atomic Line Data Base (VALD, Kupka et al., 1999A&AS..138..119K). We check that wavelengths from Arcturus and Sunspot umbra atlases identification files are in a good agreement with VALD. The wavelengths of a few lines differ from VALD values by less than 0.1Å in the region 10000-20000Å and by less than 0.3Å beyond 20000Å. Note (4): The symbol '~' means that part of the line in the hard copy of the atlas is obscured by a gap in the data and the value given in the table is for the visible part of the line. Note (5): bl means that these lines are blended with stronger nearby lines T indicates the two regions with strong telluric absorption 13600-14770Å and 18260-19450Å, regions between the J and H, and H and K photometric bands. Lines identified from VALD in these regions are difficult to observe in ground based observations but can be used in probable future space observations of ultracool dwarfs. Note (6): Linedepth information given in ArAt and SsAt is only used to check the presence of a line in the observed spectra. Thus we do not need high accuracy linedepth measurements for the observable spectra of the Sunspot umbra and Arcturus.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 9 F9.3 0.1nm lambda Wavelength 12- 15 A4 --- Atom Element name 18- 22 F5.3 --- LD Central line intensity in the ultra cool (2000/5.0/0.0) synthetic spectrum 26- 30 F5.2 % STeff Temperature sensitivity (1) 33- 38 F6.2 % Slogg ? logg sensitivity (1) 41- 46 F6.2 % S[M/H] Metallicity sensitivity (1)
Note (1): We show the difference of central intensity computations with "new" models from central intensity computations for our "ultracool dwarf model". Negative values indicate that a line is stronger in the new model relative to the reference model 2000/5.0/0.0.
Acknowledgements: Yuri Lyubchik
(End) Patricia Bauer [CDS] 27-Jan-2004
|The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line|