890 citations · 1.6k across the 12 of their papers we have counts for
13 papers
Frequency ratio of Yb and Sr clocks with uncertainty at 150 s averaging time
Nils Nemitz, Takuya Ohkubo, Masao Takamoto +4
Transition frequencies of atoms and ions are among the most accurately accessible quantities in nature, playing important roles in pushing the frontiers of science by testing funda…
Frequency ratios of Sr, Yb and Hg based optical lattice clocks and their applications
Masao Takamoto, Ichiro Ushijima, Manoj Das +8
This article describes the recent progress of optical lattice clocks with neutral strontium (Sr), ytterbium (Yb) and mercury (Hg) atoms. In particular, we pr…
Cryogenic optical lattice clocks with a relative frequency difference of
Ichiro Ushijima, Masao Takamoto, Manoj Das +2
Time and frequency are the most accurately measurable quantities, providing foundations for science and modern technologies. The accuracy relies on the SI (Systéme International) s…
Early Black Hole Formation by Accretion of Gas and Dark Matter
Hideyuki Umeda, Naoki Yoshida, Ken Nomoto +3
We propose a model in which intermediate-mass black holes (IMBHs) with mass of ~10000 Msun are formed in early dark matter halos. We carry out detailed stellar evolution calculatio…
Evolution of Very Massive Population III Stars with Mass Accretion from Pre-Main Sequence to Collapse
Takuya Ohkubo, Ken'ichi Nomoto, Hideyuki Umeda +2
We calculate the evolution of zero-metallicity Population III (Pop III) stars whose mass grows from the initial mass of by accreting the surrounding gases. Our ca…
Asymmetric Explosion of Type Ia Supernovae as Seen from Near Infrared Observations
K. Motohara, K. Maeda, C. L. Gerardy +8
We present near-infrared spectra of late phase (>200 d) Type Ia supernovae (SNe Ia) taken at the Subaru telescope. The [Fe II] line of SN 2003hv shows a clear flat-topped feature,…