• NIST physical reference data 
• -------------------
• Astronomical Constants 
• The NIST physical constants page 
• Conversion of units (Wikipedia)
• Physical constants (Wikipedia)
• SI base unit (Wikipedia)
• -------------------
• Periodic Table of Elements
• Elemental Abundance (solar, meterites, solar isotopic ratios)
• Elemental Abundance (human body)
• Elemental Abundance  (AGB Star) 
• Isotopic Ratios (terrestrial)
• Knowledge of Isotopes
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• Spectral line lists
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• Basic facts of the ecosystem of the Galaxy
• Maps of the Milky Way Galaxy
• Interstellar extinction calculation
• Prominent emission lines in Spitzer IRAC bands
• -------------------
• General star catalogues
• Gerneral definition of magnitude

Astronomical Constants (Also available: MS Word version and PDF version) [ back to top ]

1 Debye = 10^-18 (StatC cm) = 1/299792458 * 10^-21 (C m)
1 u = 1 amu = 1.660538921(73)×10^−27 kg  (unified atomic mass unit, from wikipedia: http://en.wikipedia.org/wiki/Atomic_mass_unit)

Coulomb's constant in free space: ke = 1/(4 pi epsilon_0) = 8.9875517873681764 * 10^9 N m^2 C^-2 (Wikipedia: http://en.wikipedia.org/wiki/Coulomb's_constant)

• The web based periodic table provides multimeadia information for each elements.
• A very good web based Multilingual periodic table. 
• The Krean site of Table of nuclides gives all known nuclides and relevant cross sections and photon/electron release/consumption during nuclear reactions.

• Solar abundance (mass fraction) is available from RRSN or from paper by Anders & Grevesse 1989. Here is a PDF copy of the table.
• Solar abundance from Wikipedia, see original Wiki entry or table below:
• They compiled elemental abundances in meterites, solar atmosphere, and solar corona. (from Anders & Grevesse, 1989GeCoA..53..197A)
  (tabs: left to right -- elemental abundances in the solar atmosphere, corona, meteorites and isotopic ratios)
  

Elemental abundance of human body (from Wikipedia, see original Wiki entry) [ back to top ]

Elemental abundances in an AGB star: [ back to top ]

Terrestrial isotopic ratios: (from Duley & Williams, 1984inch.book.....D) [ back to top ]

Knowledge of isotopes: [ back to top ]

The Berkeley Laboratory Isotopes Project: provide half-life, spin, parity, decay mode or abundance of all isotopes of all elements.

Spectral line lists: [ back to top ]

• UV-IR: Peter van Hoof atomic line list: 0.5 A ~ 1000um, for allowed, intercombination and forbidden atomic transitions.
• IR: Per van Hoof list of HI, DI and HeII lines: 1um ~ 196um. (a local copy made on Dec. 19, 2008)
• IR: Dieter Lutz line list: 1.9um ~ 206mu, for potentially bright atomic and ionic fine structure lines. (a local copy made on Dec. 19, 2008)
• IR: Ewine van Dishoeck list of IR molecular lines: 2.4um ~ 187um, for H2, HD, H2O, OH and CO. (a local copy made on Dec. 19, 2008)
• IR: selected IR mol lines: 50um ~ 200um, for CO, 13CO, OH, 18OH, CH, NH3, HD and HeH+. (a local copy made on Dec. 19, 2008)
• IR: H2 lines: 2.49um ~ 28.22um. (a local copy made on Dec. 19, 2008)
• IR: CO lines: 50um ~ 200.3um. (a local copy made on Dec. 19, 2008)
• IR: HF lines: 48um ~ 122um. (a local copy made on Dec. 19, 2008)
• IR: H35Cl lines: 44um ~ 160um. (a local copy made on Dec. 19, 2008)
• IR: H37Cl lines: 44um ~ 160um. (a local copy made on Dec. 19, 2008)
• mm: DiRef database - on-going updated version of Huber and Herzberg's classic book "Constants of Diatomic Molecules." (need a free account for access.)
• mm: JPL linelist
• mm: CDMS linelist
• mm: splatalogue - a molecular linelist dedicated to ALMA.
• mm: NIST Lovas linelist - frequencies from obervations.

Basic facts of the ecosystem of the Milky Way Galaxy [ back to top ]

• Morphology:
  • Thin disk radius = 25-30 kpc (Binney and Merrifield, 1998gaas.book.....B, cited by Ferriere, 2001RvMP...73.1031F)
  • Thin disk effective thickness = 400-600 pc (Binney and Merrifield, 1998gaas.book.....B, cited by Ferriere, 2001RvMP...73.1031F)
  • Spherical bulge radius = 2-3 kpc (Binney and Merrifield, 1998gaas.book.....B, cited by Ferriere, 2001RvMP...73.1031F)
  • Spherical halo radius > 30 kpc (Binney and Merrifield, 1998gaas.book.....B, cited by Ferriere, 2001RvMP...73.1031F)
  • Sun-GC distance = 8.5 kpc (Kerr and Lynden-Bell, 1986MNRAS.221.1023K)
  • Sun-Galactic disk distance = 15pc (above) (Cohen, 1995ApJ...444..874C)
  • H2 scale height (FWHM along Z axis) = 120+-18pc (Bronfman et al., 1988ApJ...324..248B)
• Kinematics
  • Stellar rotation speed near the Sun = 220 km/s (Kerr and Lynden-Bell, 1986MNRAS.221.1023K)
  • Disk star velocity dispersion = 10-40 km/s, which results in oscillation of stellar orbits (Mihalas and Binney, 1981gask.book.....M, cited by Ferriere, 2001RvMP...73.1031F)
  • Bulge and halo stars rotate slowly with highly eccentric trajectories. (Ferriere, 2001RvMP...73.1031F)
• Composition
  • Elemental abundances (by number density): H (90.8%), He (9.1%), metal (0.12%).
  • ISM mass: ~10-15% of the Galactic disk mass, with half of which located in ~1-2% of volumn. (Ferriere, 2001RvMP...73.1031F)
  • Average ISM density in the solar neighborhood = 2.7x10^-24 g/cm3 =~ 1 H/cm3. (Ferriere, 2001RvMP...73.1031F)
  • Average molecular weight = 1.42 m_H (Ferriere, 2001RvMP...73.1031F)
  • Ionization degrees: electron abundance
    • x = 10^-8 ~ 10^-6 in dense cores (Shu et al., 1987ARA&A..25...23S);
    • x = 10^-4 ~ 10^-3 in cold atomic clouds (Kulkarni and Heiles, 1987, cited by Ferriere, 2001RvMP...73.1031F);
    • x = 0.007 ~ 0.05 in warm atomic medium (Kulkarni and Heiles, 1987, cited by Ferriere, 2001RvMP...73.1031F)
• Thermodynamics
  • T ~ 10-20 K: very cold molecular gas in a cloud; (Ferriere, 2001RvMP...73.1031F)
  • T ~100 K: cold atomic gas in a cloud;(Ferriere, 2001RvMP...73.1031F)
  • T ~10^4 K: warm atomic gas; (Ferriere, 2001RvMP...73.1031F)
  • T ~10^4 K: warm ionized gas; (Ferriere, 2001RvMP...73.1031F)
  • T ~10^6 K: hot ionized gas.(Ferriere, 2001RvMP...73.1031F)
• Dynamics and timescales
  • Interstellar clouds are almost always in a critical state between self gravity and B-field. Collapse of clouds during star formation is almost always proceeding at 1~2 times of dynamical time scales (crossing time) t_dyn=(Gρ)^-1/2 = 61 n^-1/2 Myr (for H2 number density n). However, t_dyn is very different at various size scales of the collapse clouds.
    • 10^8-10^9 yr: conversion of all molecular gas into stars with the current star formation rate
    • 240 Myr: Galaxy rotation period at the position of the Sun
    • 60 Myr: tranverse time from one spiral arm to the next for the Sun (four arm spirals)
    • 30 Myr: Spiral arm traverse timescale of the Sun
    • 10-20 Myr: OB association formation
    • 5-10 Myr: OB star cluster formation
    • 3 Myr: dense OB cluster formation
    • 0.5 Myr: individual star formation
• Stars
  • Supernova rates in galaxies: 0.41h SNu for Type Ia and 1.69h SNu for Type Ib+Ic+II (h =0.7 is the Hubble constant in units of 100km/s/Mpc, SNu is the supernova unit of 1 SN per 10^10 (L_B)_sun per 100 yr). Assuming MWG is a Sbc galaxy with a blue luminosity of 2.3x 10^10 (L_B)_sun, we have Galactic SN rates: 1/220 yr for Type Ia; 1/50 yr for Type Ib+Ic+II.

Maps of the Galaxy [ back to top ]

• A complete CO, 1-0 line survey of the whole Galaxy is presented. They observed some parts and merged it with previous survey results. The spatial CO map and longitude-velocity maps are present as high resolution figures. (from Dame et al., 2001ApJ...547..792D)
  (figure: left -- low resolution CO, 1-0 map of the whole galaxy; right -- the longitude-velocity map of the CO, 1-0 Galaxy map. Warning: clicking each small figure will open a very big image file of up to 2MB!!)
  
  Also see the web link of the survey here: http://www.cfa.harvard.edu/mmw/MilkyWayinMolClouds.html.
  Another web based query graphic interface (Skyview) also provide this data: http://skyview.gsfc.nasa.gov/cgi-bin/query.pl. 
  Fits file of the above integrated CO map can downloaded here. A way to obtain original high resolution l-b-v fits data cube is also privided in this page.

Interstellar extinction [ back to top ]

• (Drimmel et al., 2003A&A...409..205D)
  They have given a 3-D Galactic extinction model based on dust distribution model. They also give Fortran and IDL programs (see FTP link: HERE) to automatically calculate the extinction Av for a give 3-D position: (RA,DEC,dist) or (L,B,dist) or ecliptic coordinates (Lecl,Becl,dist). There are several caveats:
  • it is inaccurate for dist < several hundred pc;
  • the highest resolution is 0.35deg x 0.35deg, which is limited by the COBE pixels;
  • the Galactic bar and nuclear disk are not considered;
  • it is inaccurate within 0.35 Rsun from the Galactic center, due to the bad geometry of the spiral arms adopted in the model;
  • it is inaccurate towards the line of sight of spiral arm tangents;
  • it is inaccurate towards the direction of Andromeda Galaxy, M33, the LMC and SMC, due to confusing of their background emission;
  • it is inaccurate towards the Orion and rho Ophiucus complexes, due to the anormalous dust temperatures in these nearby star forming regions.
• (Marshall et al., 2006A&A...453..635M)
  They used the Galaxy model to compute intrinsic NIR colors of stars and compare that with 2MASS data to determine the extinction distribution along different sight lines of the Milky Way. They also analyzed the strucutre of the MW galaxy with the new extinction distributions. (The 3D extinction database are given on Vizier, also provide plot of extinction ~ distance.)

Prominent emission lines in Spitzer IRAC bands

• PAH, ionic and molecular lines in the 4 IRAC bands (Reach et al., 2006AJ....131.1479R)
  (fig: left -- In the 3rd panel is a combination of H2 lines and CO band head; right -- IRAC colors due to different lines, with the arrows showing the trends of increasing line strength of the marked species.)
  
  

Gerneral star catalogues [ back to top ]

• Catalogue of Nearby Stars 3 (CNS3) or see a local copy of it here (copied on Mar. 7, 2009).

Gerneral definition of magnitude

• The standard star &a; Tau is defined as zero magnitude at any wavelength. It is spectral closely resemble a blackbody with T = 10000K. Thus the zero magnitude flux at a given frequency nu is
       fv(0.0 mag) =1.57 × 10^-16 × Bv(l0,000 K).
  For the 4 IRAS bands fv[0.00 mag] = 28.3, 6.73, 1.19 and 0.43 Jy for 12, 25, 60 and 100 µm bands respectively. Then the magnitude can be defined as
       [12] = -2.5log(F12/f12(0.0mag)) and so on.
  Then, colors [12]-[25], [25]-[60], [60]-[100] can be defined.
  (from Beichman, C. A., Neugebauer, G. Habing, H. J., Clegg, P. E., & Chester, T. J. 1988, Infrared astronomical satellite (IRAS) catalogs and atlases, Vol. 1, Explanatory Supplement, 1988iras....1.....B)
• However, some authors also define the IRAS colors in a different way. E.g., [12]-[25] = 2.5 log(F25/F12) and so on. (see van der Veen & Habing, 1988A&A...194..125V)