Zobrazeno 1 - 10
of 43
pro vyhledávání: '"David Kirkman"'
Autor:
David Kirkman
Have you ever wondered what a Dragon likes to do for fun? Or what he might look like..? Even what he likes to eat? Is it ice cream or Pasta? I'm A Dragon You See will reveal all these mysteries and more! Go on an adventure with an entertaining story
Publikováno v:
The Astrophysical Journal. 716:766-775
We use measurements of lithium abundance to examine the evolutionary history of stars frequently believed to be in a Maunder minimum (MM) state due to their low chromospheric activity. In a sample whose main-sequence membership has been verified usin
Autor:
David Tytler, Mark Gleed, Carl Melis, Angela Chapman, David Kirkman, Dan Lubin, Pascal Paschos, Tridivesh Jena, Arlin P. S. Crotts
Publikováno v:
Monthly Notices of the Royal Astronomical Society. 392:1539-1572
We present the first large sample of metal absorption systems in pairs of QSOs with sightlines separated by about 1 Mpc at z = 2. We found 691 absorption systems in the spectra of 310 QSOs in 170 pairings. Most of the systems contain C IV or MgII abs
Autor:
David Kirkman, David Tytler
Publikováno v:
Monthly Notices of the Royal Astronomical Society. 391:1457-1471
We look for signs of the H~I transverse proximity effect in the spectra of 130 QSO pairs, most with transverse separations in the plane of the sky of 0.1 -- 3 Mpc at z ~ 2.2. We expected to see a decrease in Lyman-alpha forest HI absorption in the sp
Autor:
Ryan S. Lynch, Samuel Bockenhauer, Christopher Palma, Toru Misawa, Jane C. Charlton, David Kirkman, J. R. Masiero, D. Tytler, N. Milutinovic
Publikováno v:
Monthly Notices of the Royal Astronomical Society. 382:1094-1104
We have produced a catalog of line identifications and equivalent width measurements for all absorption features in eight ultraviolet echelle quasar spectra. These spectra were selected as having the highest signal-to-noise among the HST/STIS spectra
Publikováno v:
Monthly Notices of the Royal Astronomical Society. 376:1227-1237
We measure the amount of absorption in the Lyman-alpha forest at 0 < z < 1.6 in HST FOS spectra of 74 QSOs. At 0 < z < 1.6 we find that 79% of the absorption is from the low density intergalactic medium, 12% from metals and 9% from the strong H I lin
Autor:
David Tytler, Tridivesh Jena, Kory James, Nao Suzuki, Dan Lubin, Susan Hollywood, Geoffrey C. So, Michael L. Norman, Carl Melis, David Kirkman, Pascal Paschos
Publikováno v:
Monthly Notices of the Royal Astronomical Society. 360:1373-1380
We use high quality echelle spectra of 24 QSOs to provide a calibrated measurement of the total amount of Lyman-alpha forest absorption (DA) over the redshift range 2.2 < z < 3.2. Our measurement of DA excludes absorption from metal lines or the Lyma
Publikováno v:
The Astrophysical Journal. 618:592-600
We present a method to make predictions with sets of correlated data values, in this case QSO flux spectra. We predict the continuum in the Lyman-Alpha forest of a QSO, from 1020 -- 1216 A, using the spectrum of that QSO from 1216 -- 1600 A . We find
Autor:
David Tytler, David Kirkman, John M. O’Meara, Nao Suzuki, Adam Orin, Dan Lubin, Pascal Paschos, Tridivesh Jena, Wen‐Ching Lin, Michael L. Norman, Avery Meiksin
Publikováno v:
The Astrophysical Journal. 617:1-28
We identify a concordant model for the intergalactic medium (IGM) at redshift z=1.9 that uses popular values for cosmological and astrophysical parameters and accounts for all baryons with an uncertainty of 6%. We have measured the amount of absorpti
Publikováno v:
The Astronomical Journal. 128:1058-1077
We present a moderate resolution (~1.15 Angstroms/pixel) survey of 79 quasars obtained using the Kast spectrograph on the Shane 3m telescope at Lick observatory. The spectra span the wavelength range of 3175-5880 Angstroms, and have typical signal to