A Chain of Dark Clouds in Projection Against the Galactic Center

In the J, H, and Ks bands survey of the the Galactic Center region over an area of 2deg x 5deg, we have found many dark clouds, among which a distinguished chain of dark clouds can be identified with a quiescent CO cloud. The distances of the clouds is estimated to be 3.2-4.2 kpc, corresponding to the Norma arm by our new method to determine distance to dark clouds using the cumulative number of stars against J-Ks colors. Adopting these estimated distances, the size is about 70 pc in length and the total mass of the cloud is 6x10^4 M_solar. Three compact HII regions harbor in the cloud, indicating that star forming activities are going on at the cores of the quiescent CO cloud on the spiral arm.Comment: 13 pages, 7 figures, accepted for publication in PAS

OCURRENCE OF LINGULAPHOLIS (CRANIOPSIDAE, BRACHIOPODA) IN THE PIMENTEIRA FORMATION (DEVONIAN, PARNAÍBA BASIN): Registro de Lingulapholis (Craniopsidae, Brachiopoda) na Formação Pimenteira (Devoniano, Bacia de Parnaíba)

The genus Lingulapholis had temporal and spatial restrictions during the Devonian, being found only in Colombia and the United States. In Brazil, its related taxa Craniops is common in the Amazonas, Paraná, and Parnaíba basins. New data from the cities of Picos and Itainópolis, east flank of Parnaíba Basin, led to the discovery of a yet previously undescribed brachiopod genus for this region of Gondwana. The Lingulapholis brachiopod was found associated with plant fragments under conditions of moderate to low hydrodynamic energy as indicated by ichnological assemblage, in proximal expressions of Cruziana ichnofacies alternated to Skolithos ichnofacies. The presence of Lingulapholis suggests that the Parnaíba Basin was inserted in the zone of diffuse faunal mixing during the Middle Devonian.ABSTRACT - The genus Lingulapholis had temporal and spatial restrictions during the Devonian, being found only in Colombia and the United States. In Brazil, its related taxa Craniops is common in the Amazonas, Paraná, and Parnaíba basins. New data from the cities of Picos and Itainópolis, east flank of Parnaíba Basin, led to the discovery of a yet previously undescribed brachiopod genus for this region of Gondwana. The Lingulapholis brachiopod was found associated with plant fragments under conditions of moderate to low hydrodynamic energy as indicated by ichnological assemblage, in proximal expressions of Cruziana ichnofacies alternated to Skolithos ichnofacies. The presence of Lingulapholis suggests that the Parnaíba Basin was inserted in the zone of diffuse faunal mixing during the Middle Devonian. RESUMO - - O gênero Lingulapholis teve restrições temporais e espaciais durante o Devoniano, sendo encontrado apenas na Colômbia e nos Estados Unidos. No Brasil, seu táxon relacionado Craniops é comum nas bacias do Amazonas, Paraná e Parnaíba. Novos dados das cidades de Picos e Itainópolis, flanco leste da Bacia do Parnaíba, levaram à descoberta de um gênero de braquiópode ainda não descrito para esta região do Gondwana. O braquiópode Lingulapholis foi encontrado associado a fragmentos de plantas em condições de moderada a baixa energia hidrodinâmica, conforme indicado pela assembleia icnológica, em expressões próximas de icnofácies Cruziana alternadas a icnofácies Skolithos. A presença de Lingulapholis sugere que a Bacia do Parnaíba esteve inserida na zona de mistura faunística difusa durante o Devoniano Médio

Variable Stars in the Magellanic Clouds: Results from OGLE and SIRIUS

We have performed a cross-identification between OGLE-II data and single-epoch SIRIUS JHK survey data in the LMC and SMC. After eliminating obvious spurious variables, we determined the pulsation periods for 9,681 and 2,927 variables in the LMC and SMC, respectively. Based on these homogeneous data, we studied the pulsation properties and metallicity effects on period-K magnitude (PK) relations by comparing the variable stars in the LMC and SMC. The sample analyzed here is much larger, and we found the following new features: (1) variable red giants in the SMC form parallel sequences on the PK plane, just like those found by Wood (2000) in the LMC; (2) both of the sequences A and B of Wood (2000) have discontinuities, and they occur at the K-band luminosity of the TRGB; (3) the sequence B of Wood (2000) separates into three independent sequences B+- and C'; (4) comparison between the theoretical pulsation models (Wood et al. 1996) and observational data suggests that the variable red giants on sequences C and newly discovered C' are pulsating in the fundamental and first overtone mode, respectively; (5) the theory can not explain the pulsation mode of sequences A+- and B+-, and they are unlikely to be the sequences for the first and second overtone pulsators, as was previously suggested; (6) the zero points of PK relations of Cepheids in the metal deficient SMC are fainter than those of LMC ones by ~0.1 mag but those of SMC Miras are brighter than those of LMC ones by ~0.13 mag, which are probably due to metallicity effects.Comment: 9 pages, 10 figures, accepted for publication in MNRAS. High resolution version is available at: http://www.ioa.s.u-tokyo.ac.jp/~yita/scr/astro/papers/RefereedPaper/yitaMD250 .pd

Near-Infrared Imaging Polarimetry of the NGC 2071 Star Forming Region with SIRPOL

We have conducted deep JHKs imaging polarimetry of a ~8' x 8' area of the NGC 2071 star forming region. Our polarization data have revealed various infrared reflection nebulae (IRNe) associated with the central IR young star cluster NGC2071IR and identified their illuminating sources. There are at least 4 IRNe in NGC2071IR and several additional IRNe are identified around nearby young stars in the same field-of-view. Each illuminating source coincides with a known near-IR source except for IRS3, which is only a part of IRN2 and is illuminated by the radio source 1c. Aperture polarimetry of each cluster source is used to detect unresolved circumstellar disk/outflow systems. Aperture polarimetry of the other point-like sources within the field is made in this region for the first time. The magnetic field structures (from ~1 pc down to \~0.1 pc) are derived using both aperture polarimetry of the point-like sources and imaging polarimetry of the shocked H2 emission that is seen as the dominant knotty nebulae in the Ks band image; they are both of dichroic origin and the derived field directions are consistent with each other. The magnetic field direction projected on the sky is also consistent with that inferred from the 850 micron thermal continuum emission polarimetry of the central 0.2 pc region, but running roughly perpendicular (~75 degrees) to the direction of the large scale outflow. We argue that the field strength is too weak to align the outflow in the large scale field direction via magnetic braking.Comment: o appear in PASJ, 9 pages, 11 Postscript figure

The Infrared Counterpart of the X-Ray Nova XTE J1720-318

We report on the discovery of an infrared counterpart to the X-ray transient XTE J1720-318 on 2003 January 18, nine days after an X-ray outburst, and the infrared light curve during the first 130 days after the outburst. The infrared light curve shows a decline of about 1.2 mag from the peak magnitude of Ks about 15.3 over the observation period, and a secondary maximum, about 40 days after the outburst. Another small increase in the flux was also recorded about 20 days after the outburst. These increases were also detected in the X-ray light curve. The J H Ks colors are consistent with an X-ray irradiated accretion disk suffering an extinction of Av about 8, which is also inferred from its X-ray spectrum and the extinction map constructed from far-infrared dust emission of this line of sight. These J, H, and Ks observations demonstrate that useful data can be obtained even for such an object, which suffers heavy optical extinction, possibly located beyond the Galactic center.Comment: 5 pages, 2 figures, to appear in PAS