scholarly journals VVV WIN 1733−3349: a low extinction window to probe the far side of the Milky Way bulge

2020 ◽  
Vol 494 (1) ◽  
pp. L32-L36 ◽  
Author(s):  
R K Saito ◽  
D Minniti ◽  
R A Benjamin ◽  
M G Navarro ◽  
J Alonso-García ◽  
...  
Keyword(s):  
Stellar Population ◽  
Milky Way ◽  
Galactic Structure ◽  
Density Fluctuations ◽  
Surrounding Area ◽  
Low Latitude ◽  
The Past ◽  
Near Ir ◽  
The Mean ◽  
Red Clump

ABSTRACT Windows of low extinction in the Milky Way (MW) have been used along the past decades for the study of the Galactic structure and the stellar population across the inner bulge and disc. Here, we report the analysis of another low extinction near-IR window discovered by the VISTA Variables in the Vía Láctea Survey (VVV). VVV WIN 1733−3349 is about half a degree in size and is conveniently located right in the MW plane, at Galactic coordinates (l, b) = (−5.2, −0.3). The mean extinction of VVV WIN 1733−3349 is $A_{K_{\mathrm{ s}}}$ = 0.61 ± 0.08 mag, which is much smaller than the extinction in the surrounding area. The excess in the star counts is consistent with the reduced extinction and complemented by studying the distribution of red clump (RC) stars. Thanks to the strategic low-latitude location of VVV WIN 1733−3349, we are able to interpret their RC density fluctuations with the expected overdensities due to the presence of the spiral arms beyond the bulge. In addition, we find a clear excess in the number of microlensing events within the window, which corroborates our interpretation that VVV WIN 1733−3349 is revealing the far side of the MW bulge.

scholarly journals A new near-IR window of low extinction in the Galactic plane

2018 ◽  
Vol 616 ◽  
pp. A26 ◽  
Author(s):  
Dante Minniti ◽  
Roberto K. Saito ◽  
Oscar A. Gonzalez ◽  
Javier Alonso-García ◽  
Marina Rejkuba ◽  
...  
Keyword(s):  
Near Infrared ◽  
Milky Way ◽  
Galactic Plane ◽  
Structural Constraints ◽  
Magnitude Distribution ◽  
Near Ir ◽  
Disk Structure ◽  
The Galaxy ◽  
The Mean ◽  
Red Clump

Aims. The windows of low extinction in the Milky Way (MW) plane are rare but important because they enable us to place structural constraints on the opposite side of the Galaxy, which has hither to been done rarely. Methods. We use the near-infrared (near-IR) images of the VISTA Variables in the Vía Láctea (VVV) Survey to build extinction maps and to identify low extinction windows towards the Southern Galactic plane. Here we report the discovery of VVV WIN 1713−3939, a very interesting window with relatively uniform and low extinction conveniently placed very close to the Galactic plane. Results. The new window of roughly 30 arcmin diameter is located at Galactic coordinates (l, b) = (347.4, −0.4) deg. We analyse the VVV near-IR colour-magnitude diagrams in this window. The mean total near-IR extinction and reddening values measured for this window are AKs = 0.46 and E(J − Ks) = 0.95. The red clump giants within the window show a bimodal magnitude distribution in the Ks band, with peaks at Ks = 14.1 and 14.8 mag, corresponding to mean distances of D = 11.0 ± 2.4 and 14.8 ± 3.6 kpc, respectively. We discuss the origin of these red clump overdensities within the context of the MW disk structure.

scholarly journals The last breath of the Sagittarius dSph

2020 ◽  
Vol 497 (4) ◽  
pp. 4162-4182 ◽  
Author(s):  
Eugene Vasiliev ◽  
Vasily Belokurov
Keyword(s):  
Milky Way ◽  
Dwarf Galaxy ◽  
3D Structure ◽  
Major Axis ◽  
Final State ◽  
Tidal Forces ◽  
The Galaxy ◽  
The Mean ◽  
Red Clump ◽  
Astrometric Data

ABSTRACT We use the astrometric and photometric data from Gaia Data Release 2 and line-of-sight velocities from various other surveys to study the 3D structure and kinematics of the Sagittarius dwarf galaxy. The combination of photometric and astrometric data makes it possible to obtain a very clean separation of Sgr member stars from the Milky Way foreground; our final catalogue contains 2.6 × 105 candidate members with magnitudes G < 18, more than half of them being red clump stars. We construct and analyse maps of the mean proper motion and its dispersion over the region ∼30 × 12 deg, which show a number of interesting features. The intrinsic 3D density distribution (orientation, thickness) is strongly constrained by kinematics; we find that the remnant is a prolate structure with the major axis pointing at ∼45° from the orbital velocity and extending up to ∼5 kpc, where it transitions into the stream. We perform a large suite of N-body simulations of a disrupting Sgr galaxy as it orbits the Milky Way over the past 2.5 Gyr, which are tailored to reproduce the observed properties of the remnant (not the stream). The richness of available constraints means that only a narrow range of parameters produce a final state consistent with observations. The total mass of the remnant is $\sim \!4\times 10^8\, \mathrm{M}_\odot$, of which roughly a quarter resides in stars. The galaxy is significantly out of equilibrium, and even its central density is below the limit required to withstand tidal forces. We conclude that the Sgr galaxy will likely be disrupted over the next Gyr.

scholarly journals Star Counts and the Milky Way Structure

1994 ◽  
Vol 161 ◽  
pp. 403-410 ◽  
Author(s):  
A.C. Robin
Keyword(s):  
Stellar Population ◽  
Milky Way ◽  
Galactic Structure ◽  
Galactic Evolution ◽  
Population Characteristics ◽  
Comprehensive Picture ◽  
Synthetic Models

While the accuracy of photometric star counts rises, constraints on the stellar population characteristics improve and allow synthetic models to be conceived to explain the galactic structure. We show here how star counts have significantly contributed to build a comprehensive picture of galactic evolution and dynamics.

scholarly journals Comparison of NIRS0S Ks-band and S4G 3.6 micron data: Fourier amplitudes, force profiles and color maps

2012 ◽  
Vol 10 (H16) ◽  
pp. 332-332
Author(s):  
Heikki Salo ◽  
Eija Laurikainen ◽  
Keyword(s):  
Stellar Population ◽  
Stellar Structure ◽  
Disk Galaxies ◽  
The Past ◽  
Near Ir ◽  
Wide Range ◽  
Nuclear Ring ◽  
Nearby Galaxies ◽  
Spiral Structures ◽  
Force Profiles

AbstractNear-IR observations are considered to give an extinction-free view of the old stellar population in galaxies, thus ideal for the analysis of gravitational torques associated with bar and spiral structures. In the past, H or Ks band data have often been employed (Buta et al. 2010, Salo et al. 2010). S4G (Spitzer Survey of Stellar Structure in Galaxies, Sheth et al. 2010) provides new deep homogenious 3.6 and 4.5 micron data for over 2000 nearby galaxies, allowing to probe the bar and spiral properties over a wide range of morphological types and environments. Here we compare the Fourier-amplitude profiles derived from S4G data for about 50 early-type disk galaxies (SO and S0/a), with those from NIRSOS Ks data (Near-IR S0 Survey, Laurikainen et al. 2011). We also make detailed Ks-3.6 micron color maps. Interestingly, nuclear ring features stand up very clearly in these maps, indicating significantly different contributions of recent star formation in the Ks and 3.6 micron bands. However, the effect of these detailed differences on the overall force profiles is fairly small: this confirms that the S4G data can be confidently used for estimation of bar torques.

scholarly journals The age-kinematical features in the Milky Way outer disk

2016 ◽  
Vol 11 (S321) ◽  
pp. 6-9 ◽  
Author(s):  
Chao Liu ◽  
Hai-Jun Tian ◽  
Jun-Chen Wan
Keyword(s):  
Milky Way ◽  
Mean Velocity ◽  
Outer Disk ◽  
Center Region ◽  
Bulk Motion ◽  
Age Variation ◽  
The Mean ◽  
Red Clump ◽  
Galactic Warp

AbstractWe derive the mean velocity components at various Galactocentric radii from 8 to 14 kpc using about 40,000 red clump stars observed in the LAMOST survey. We find that the vertical bulk motion for younger red clump stars are significantly larger than that for the older red clump stars. This is likely the kinematical feature of the Galactic warp around its line-of-node, which is located close to the Galactic anti-center region. It is evident that the warp are mainly contributed by the younger stars rather than the older stars. The age variation in the vertical kinematics favors a formation scenario where the Galactic warp is originated from infalling misaligned gas.

scholarly journals The Milky Way bar/bulge in proper motions: a 3D view from VIRAC and Gaia

2019 ◽  
Vol 489 (3) ◽  
pp. 3519-3538 ◽  
Author(s):  
Jonathan P Clarke ◽  
Christopher Wegg ◽  
Ortwin Gerhard ◽  
Leigh C Smith ◽  
Phil W Lucas ◽  
...  
Keyword(s):  
Proper Motion ◽  
Milky Way ◽  
Selection Function ◽  
Full Potential ◽  
Proper Motions ◽  
Bulge Region ◽  
Similar Distance ◽  
Pattern Speed ◽  
The Mean ◽  
Red Clump

Abstract We have derived absolute proper motions of the entire Galactic bulge region from VVV Infrared Astrometric Catalogue (VIRAC) and Gaia. We present these both as integrated on-sky maps and, after isolating standard candle red clump (RC) stars, as a function of distance using RC magnitude as a proxy. These data provide a new global, 3D view of the Milky Way barred bulge kinematics. We find a gradient in the mean longitudinal proper motion, $\langle \mu _ l^\star \rangle $, between the different sides of the bar, which is sensitive to the bar pattern speed. The split RC has distinct proper motions and is colder than other stars at similar distance. The proper motion correlation map has a quadrupole pattern in all magnitude slices showing no evidence for a separate, more axisymmetric inner bulge component. The line-of-sight integrated kinematic maps show a high central velocity dispersion surrounded by a more asymmetric dispersion profile. $\sigma _{\mu _l} / \sigma _{\mu _b}$ is smallest, ≈1.1, near the minor axis and reaches ≈1.4 near the disc plane. The integrated $\langle \mu_b\rangle$ pattern signals a superposition of bar rotation and internal streaming motion, with the near part shrinking in latitude and the far part expanding. To understand and interpret these remarkable data, we compare to a made-to-measure barred dynamical model, folding in the VIRAC selection function to construct mock maps. We find that our model of the barred bulge, with a pattern speed of 37.5 $\mathrm{ \mathrm{ km \, s^{-1}} \, kpc^{-1} }$, is able to reproduce all observed features impressively well. Dynamical models like this will be key to unlocking the full potential of these data.

Scrub typhus (Orientia tsutsugamushi), A rapidly spreading epidemic in Chennai - A standalone lab experience

2016 ◽  
Vol 5 (09) ◽  
pp. 4896
Author(s):  
Sripriya C.S.* ◽  
Shanthi B. ◽  
Arockia Doss S. ◽  
Antonie Raj I. ◽  
Mohana Priya
Keyword(s):  
Scrub Typhus ◽  
Clinical Symptoms ◽  
Clinical Manifestations ◽  
Febrile Illness ◽  
Orientia Tsutsugamushi ◽  
The Past ◽  
Igm Elisa ◽  
The Mean ◽  
Specific Symptoms ◽  
Symptoms And Signs

Scrub typhus (Orientia tsutsugamushi), is a strict intracellular bacterium which is reported to be a recent threat to parts of southern India. There is re-emergence of scrub typhus during the past few years in Chennai. Scrub typhus is an acute febrile illness which generally causes non-specific symptoms and signs. The clinical manifestations of this disease range from sub-clinical disease to organ failure to fatal disease. This study documents our laboratory experience in diagnosis of scrub typhus in patients with fever and suspected clinical symptoms of scrub typhus infection for a period of two years from April 2014 to April 2016 using immunochromatography and IgM ELISA methods. The study was conducted on 648 patients out of whom 188 patients were found to be positive for scrub typhus. Results also showed that pediatric (0 -12 years) and young adults (20 – 39 years) were more exposed to scrub typhus infection and female patients were more infected compared to male. The study also showed that the rate of infection was higher between September to February which also suggested that the infection rate is proportional to the climatic condition. Statistical analysis showed that the mean age of the patients in this study was 37.6, standard deviation was 18.97, CV % was 50.45. 

The Long View of Planetary Systems

2018 ◽  
Author(s):  
Karel Schrijver
Keyword(s):  
Solar System ◽  
Milky Way ◽  
Planetary Systems ◽  
Giant Planets ◽  
Milky Way Galaxy ◽  
Population Statistics ◽  
The Past ◽  
General Terms ◽  
The Galaxy ◽  
The Universe

How many planetary systems formed before our’s did, and how many will form after? How old is the average exoplanet in the Galaxy? When did the earliest planets start forming? How different are the ages of terrestrial and giant planets? And, ultimately, what will the fate be of our Solar System, of the Milky Way Galaxy, and of the Universe around us? We cannot know the fate of individual exoplanets with great certainty, but based on population statistics this chapter sketches the past, present, and future of exoworlds and of our Earth in general terms.

scholarly journals Relaxation Times in Strictly Disk Systems

1971 ◽  
Vol 10 ◽  
pp. 15-19
Author(s):  
George B. Rybicki
Keyword(s):  
Numerical Experiments ◽  
Relaxation Times ◽  
Galactic Structure ◽  
Large Numbers ◽  
Order Of Magnitude ◽  
Vlasov Limit ◽  
The Mean ◽  
Gravitating Systems

AbstractIt is shown that the time of relaxation by particle encounters of self-gravitating systems in the plane interacting by 1/r2 forces is of the same order of magnitude as the mean orbit time. Therefore such a system does not have a Vlasov limit for large numbers of particles, unless appeal is made to some non-zero thickness of the disk. The relevance of this result to numerical experiments on galactic structure is discussed.

scholarly journals 797. Management of Patients with Multiple Clostridioides difficile Infection Recurrences using a Tapered-Pulsed Fidaxomicin Strategy

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S441-S442
Author(s):  
Xing Tan ◽  
Andrew M Skinner ◽  
Benjamin Sirbu ◽  
Larry H Danziger ◽  
Dale N Gerding ◽  
...  
Keyword(s):  
First Episode ◽  
Initial Symptom ◽  
Once Daily ◽  
The Past ◽  
Clostridioides Difficile ◽  
Time To Recurrence ◽  
Clostridioides Difficile Infection ◽  
The Mean ◽  
Systemic Antibiotics

Abstract Background There is a paucity of data assessing outcomes of alternate fidaxomicin strategies in patients with recurrent Clostridioides difficile infection (rCDI). The objective of our study is to evaluate a tapered-pulsed (T-P) fidaxomicin regimen that was administered immediately following a course of CDI treatment with initial symptom resolution in patients with multiple rCDI. Methods We reviewed the characteristics and outcomes of 46 consecutive patients who received T-P fidaxomicin between January 1, 2014-June 30, 2019 in a specialty CDI clinic. The first episode in which fidaxomicin T-P was administered was analyzed. Failure was defined as the persistence of diarrhea and/or the need for additional CDI treatment at any time on T-P fidaxomicin. Sustained clinical cure (SCC) was defined as resolution of diarrhea without recurrence. Recurrence was defined as the return of diarrhea requiring retreatment with CDI therapy after completion of T-P fidaxomicin. Both SCC and recurrence were evaluated at 30 and 90 days after completion of T-P fidaxomicin. Results The mean±SD age of the 46 patients was 63.2±19.9 years, 71.7% were female, and the mean±SD CDI episodes within the past year was 3±1.4 . Most patients (73.9%) had previously failed a vancomycin tapered and/or pulsed regimen. Prior to administering T-P fidaxomicin, a treatment regimen was given to ensure resolution of symptoms. The CDI treatment most commonly used (58.7%) was vancomycin. The T-P fidaxomicin regimen used consisted of 200 mg given once daily for 7 days followed by 200 mg every other day for a median (min-max) duration of 33 (6-120) days. Two patients (4%) failed to respond to T-P fidaxomicin; 34 (74%) and 28 (61%) achieved SCC at 30 and 90 days, respectively. Among the 44 patients that successfully completed the T-P fidaxomicin regimen, recurrence developed in 10 (22.7%) and 16 (36.4%) of patients at 30 and 90 days, respectively, with a median (min-max) time to recurrence of 20 (3-87) days (Figure 1). Four patients with recurrence had received subsequent systemic antibiotics. Figure 1. Course of CDI therapy and follow-up Conclusion A tapered-pulsed fidaxomicin strategy may be effective in patients with multiply rCDI who are refractory to other treatments, including a vancomycin tapered and pulsed regimen. Disclosures Larry H. Danziger, PharmD, Merck (Speaker’s Bureau)

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