Search Publications
Photochemistry of Methane and Ethane in the Martian Atmosphere
Taysum, Benjamin M.; Palmer, Paul I.
We develop an existing 1-D photochemistry model to include a comprehensive description of organic chemistry on Mars that includes the oxidation products of methane (CH4) and ethane (C2H6),a longer-chain hydrocarbon that can be used to differentiate between abiotic and biotic surface releases of CH4. We f…
ALMA reveals the coherence of the magnetic field geometry in OH 231.8+4.2
Sahai, R.; Zijlstra, A. A.; Sabin, L. +7 more
In a continuing effort to investigate the role of magnetic fields in evolved low- and intermediate-mass stars (principally regarding the shaping of their envelopes), we present new Atacama Large Millimeter/submillimeter Array (ALMA) high-resolution polarization data obtained for the nebula OH 231.8+4.2. We found that the polarized emission likely …
On the metallicity gradient in the Galactic disk
Loktin, Alexander; Popova, Maria
The problem of the chemical composition gradient in the Galactic disk is studied based on a sample of metallicity estimates of open star clusters, using Gaia DR2-improved distance estimates. A clearly non-monotonic variation was observed in the average metallicity of clusters with increasing Galactocentric distance. One can clearly see the metalli…
Exhaustive study of three-time periods of solar activity due to single active regions: sunspot, flare, CME, and geo-effectiveness characteristics
Soni, Shirsh Lata; Yadav, Manohar Lal; Gupta, Radhe Syam +1 more
In this paper, we present the multi-wavelength study of a high level of solar activity during which a single active region produced multiple flares/CMEs. According to the sunspot observations, the current solar cycle 24 manifest to be less intense in comparison with the previous recent sunspot cycles. In the course of the current sunspot cycle 24,…
The Herschel SPIRE Fourier Transform Spectrometer Spectral Feature Finder - II. Estimating radial velocity of SPIRE spectral observation sources
Valtchanov, Ivan; Scott, Jeremy P.; Spencer, Locke D. +3 more
The Herschel SPIRE FTS Spectral Feature Finder (FF) detects significant spectral features within SPIRE spectra and employs two routines, and external references, to estimate source radial velocity. The first routine is based on the identification of rotational 12CO emission, the second cross-correlates detected features with a line temp…
Identification of a new ultraluminous X-ray source in NGC 1316
Ozdogan Ela, M.; Akyuz, A.; Aksaker, N. +3 more
In this study, we report identification of a new ultraluminous X-ray source (ULX) named as X-7 in NGC 1316, with an unabsorbed luminosity of 2.1 × 1039 erg s-1 using the two recent Chandra archival observations. The X-7 was detected in the Chandra 2001 observation and was included in the source list of the NGC 1316 as CXOUJ03…
ISO-ChaI 52: a weakly accreting young stellar object with a dipper light curve
Fedele, D.; Alcalá, J. M.; Manara, C. F. +6 more
We report the discovery of periodic dips in the multiband light curve of ISO-ChaI 52, a young stellar object in the Chamaeleon I dark cloud. This is one of the peculiar objects that display very low or negligible accretion in their UV continuum and spectral lines, although they present a remarkable infrared excess emission characteristic of optica…
Lessons on early structure formation from a mature galaxy cluster observed at cosmic noon
Bromm, Volker; Liu, Boyuan; Schauer, Anna T. P.
We demonstrate a new approach of indirectly constraining both early star and structure formation via mature galaxy clusters at cosmic noon (z ∼ 2), using the cluster XLSSC 122 as an example. With the standard Press Schechter formalism, we infer a rapid evolution of the star formation efficiency (the ratio of stellar to halo mass) from 10-4
The Energetic Thermonuclear Bursts in SAX J1712.6-3739
Lin, Jie; Yu, Wenfei
The neutron star low-mass X-ray binary SAX J1712.6-3739 is known for its long and hard thermonuclear X-ray bursts from previous observations. Its thermonuclear bursts are so distinct as they can last for tens of minutes, as seen with Swift/BAT (E > 15 keV). To explore the origin of these extreme bursts and the nature of SAX J1712.6-3739, we ana…
Study of Star-Forming Regions in the Peculiar Galaxies NGC 660, NGC 1512, NGC 4395, and NGC 4618
Smirnova, K. I.; Wiebe, D. S.; Moiseev, A. V. +1 more
—The star-forming regions (SFRs) in the peculiar galaxies NGC 660, NGC 1512, NGC 4395 and NGC 4618 are studied. The relationships between such characteristics of star forming regions as UV, near- and far-IR fluxes, as well as in the Hα and HI lines, surface brightness in these ranges, and the scatter of the radial velocities of ionized and neutral…