Search Publications
How does pressure gravitate? Cosmological constant problem confronts observational cosmology
Afshordi, Niayesh; Scott, Douglas; Narimani, Ali
An important and long-standing puzzle in the history of modern physics is the gross inconsistency between theoretical expectations and cosmological observations of the vacuum energy density, by at least 60 orders of magnitude, otherwise known as the cosmological constant problem. A characteristic feature of vacuum energy is that it has a pressure …
The Herschel view of circumstellar discs: a multiwavelength study of Chamaeleon-I
Ray, Tom; Scholz, Alexander; Rodgers-Lee, Donna +1 more
We present the results of a multiwavelength study of circumstellar discs around 44 young stellar objects in the 3 myr old nearby Chamaeleon-I star-forming region. In particular, we explore the far-infrared/submm regime using Herschel fluxes. We show that Herschel fluxes at 160-500 µm can be used to derive robust estimates of the disc mass. T…
Herschel-PACS measurements of nitrogen enrichment in nebulae around Wolf-Rayet stars
Barlow, M. J.; Stock, D. J.
For three nebulae that have early-WN Wolf-Rayet exciting stars, NGC 6888, WR 8 and Abell 48, we have obtained Herschel-PACS line scans of the [N III] 57-µm and [O III] 88-µm lines, along with the 122- and 205-µm lines of [N II]. From the former two lines we have derived N2+/O2+ abundance ratios, equal to the…
C1XS results-First measurement of enhanced sodium on the lunar surface
Grande, M.; Narendranath, S.; Sreekumar, P. +1 more
We describe the first unambiguous evidence of enhanced sodium on the lunar surface revealed by the Chandrayaan-1 X-ray Spectrometer (C1XS). The C1XS onboard the Chandrayaan-1 spacecraft was designed to map the surface elemental chemistry of the Moon using the X-ray fluorescence (XRF) technique. During the nine months of remote sensing observations…
An Optical-Near-IR Study of a Triplet of Super Star Clusters in the Starburst Core of M82
O'Connell, R. W.; Rosa González, D.; Bastian, N. +8 more
We present HST/STIS optical and Gemini/NIFS near-IR IFU spectroscopy and archival Hubble Space Telescope (HST) imaging of the triplet of super star clusters (A1, A2, and A3) in the core of the M82 starburst. Using model fits to the Space Telescope Imaging Spectrograph (STIS) spectra and the weakness of red supergiant CO absorption features (appear…
Infrared Spectra of Acetylene Diluted in Solid Nitrogen upon Irradiation with Vacuum Ultraviolet Light and Electrons
Chen, Sian-Cong; Huang, Tzu-Ping; Wu, Yu-Jong +1 more
Infrared spectra and chemical reactions of acetylene diluted in solid nitrogen at 10 K upon irradiation with vacuum ultraviolet (VUV) light and energetic electrons were investigated in separate experiments. Irradiation of the matrix sample with VUV light peaking at 160 and 121.6 nm yielded simple products, including C2H, CN, and isomers…
Properties of M31. IV. Candidate Luminous Blue Variables from PAndromeda
Price, P. A.; Bianchi, L.; Chambers, K. C. +16 more
We perform a study on the optical and infrared photometric properties of known luminous blue variables (LBVs) in M31 using a sample of LBV candidates from the Local Group Galaxy Survey by Masset et al. We find that M31 LBV candidates show photometric variability ranging from 0.375 to 1.576 mag in r P1 during a 3 yr time span observed by…
Discovery of X-ray pulsations in the Be/X-ray binary IGR J21343+4738
Zezas, A.; Reig, P.
We report on the discovery of X-ray pulsations in the Be/X-ray binary IGR J21343+4738 during an XMM-Newton observation. We obtained a barycentric corrected pulse period of 320.35 ± 0.06 s. The pulse profile displays a peak at low energy that flattens at high energy. The pulse fraction is 45 ± 3 per cent and independent of energy within the statist…
Modeling and predicting the shape of the far-infrared to submillimeter emission in ultra-compact HII regions and cold clumps
Bernard, J. -P.; Paladini, R.; Rivera-Ingraham, A. +8 more
Context. Dust properties are very likely affected by the environment in which dust grains evolve. For instance, some analyses of cold clumps (7-17 K) indicate that the aggregation process is favored in dense environments. However, studying warm (30-40 K) dust emission at long wavelength (λ> 300 µm) has been limited because it is difficult…
OMC/INTEGRAL photometric observations of pulsating components in eclipsing binaries and characterization of DY Aqr
Montesinos, B.; Mas-Hesse, J. M.; Martín-Ruiz, S. +2 more
We present the search for eclipsing binaries with a pulsating component in the first catalogue of optically variable sources observed by Optical Monitoring Camera (OMC)/INTEGRAL, which contains photometric data for more than 1000 eclipsing binaries. Five objects were found and a detailed analysis of one of them, DY Aqr, has been performed. Photome…