- ID:
- ivo://CDS.VizieR/J/MNRAS/421/3257
- Title:
- MHO catalogue for Serpens and Aquila
- Short Name:
- J/MNRAS/421/3257
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Jets and outflows from young stellar objects (YSOs) are important signposts of currently ongoing star formation. In order to study these objects, we are conducting an unbiased survey along the Galactic plane in the 1-0 S(1) emission line of molecular hydrogen at 2.122 um using the United Kingdom Infrared Telescope. In this paper, we are focusing on a 33-deg^2^-sized region in Serpens and Aquila (18{deg}<l<30{deg}; -1.5{deg}<b<+1.5{deg}). We trace 131 jets and outflows from YSOs, which results in a 15-fold increase in the total number of known molecular hydrogen outflows. Compared to this, the total integrated 1-0 S(1) flux of all objects just about doubles, since the known objects occupy the bright end of the flux distribution. Our completeness limit is 3x10^-18^W/m^2^ with 70 per cent of the objects having fluxes of less than 10^-17^W/m^2^.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/249/16
- Title:
- Microlensing event in the OGLE-IV GVS survey
- Short Name:
- J/ApJS/249/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Searches for gravitational microlensing events are traditionally concentrated on the central regions of the Galactic bulge but many microlensing events are expected to occur in the Galactic plane, far from the Galactic Center. Owing to the difficulty in conducting high-cadence observations of the Galactic plane over its vast area, which are necessary for the detection of microlensing events, their global properties were hitherto unknown. Here, we present results of the first comprehensive search for microlensing events in the Galactic plane. We searched an area of almost 3000 square degrees along the Galactic plane (|b|<7{deg}, 0{deg}<l<50{deg}, 190{deg}<l<360{deg}) observed by the Optical Gravitational Lensing Experiment (OGLE) during 2013-2019 and detected 630 events. We demonstrate that the mean Einstein timescales of Galactic plane microlensing events are on average three times longer than those of Galactic bulge events, with little dependence on the Galactic longitude. We also measure the microlensing optical depth and event rate as a function of Galactic longitude and demonstrate that they exponentially decrease with the angular distance from the Galactic Center (with the characteristic angular scale length of 32{deg}). The average optical depth decreases from 0.5x10^-6^ at l=10{deg} to 1.5x10^-8^ in the Galactic anticenter. We also find that the optical depth in the longitude range 240{deg}<l<330{deg} is asymmetric about the Galactic equator, which we interpret as a signature of the Galactic warp.
- ID:
- ivo://CDS.VizieR/J/ApJ/778/150
- Title:
- Microlensing events toward the Bulge from MOA-II
- Short Name:
- J/ApJ/778/150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of the microlensing optical depth and event rate toward the Galactic Bulge (GB) based on two years of the MOA-II survey. This sample contains ~1000 microlensing events, with an Einstein radius crossing time of t_E_<=200 days in 22 bulge fields covering ~42deg^2^ between -5{deg}<l<10{deg} and -7{deg}<b<-1{deg}. Our event rate and optical depth analysis uses 474 events with well-defined microlensing parameters. In the central fields with |l|<5{deg}, we find an event rate of {Gamma}=[2.39+/-1.1]e^[0.60+/-0.05](3-|b|)^x10^-5^/star/yr and an optical depth (for events with t_E_<=200days) of {tau}_200_=[2.35+/-0.18]e^[0.51+/-0.07](3-|b|)^x10^-6^ for the 427 events, using all sources brighter than I_s_<=20mag. The distribution of observed fields is centered at (l,b)=(0.{deg}38, -3.{deg}72). We find that the event rate is maximized at low latitudes and a longitude of l{approx}1{deg}. For the 111 events in 3.2deg^2^ of the central GB at |b|<=3.{deg}0 and 0.{deg}0<=l<=2.{deg}0, centered at (l,b)=(0.{deg}97, -2.{deg}26), we find {Gamma}=4.57_-0.46_^+0.51^x10^-5^/star/yr and {tau}_200_=3.64_-0.45_^+0.51^x10^-6^. We also consider a red clump giant (RCG) star sample with I_s_<17.5, and we find that the event rate for the RCG sample is slightly lower than but consistent with the all-source event rate. The main difference is the lack of long duration events in the RCG sample due to a known selection effect. Our results are consistent with previous optical depth measurements, but they are somewhat lower than previous all-source measurements, and slightly higher than previous RCG optical depth measurements. This suggests that the previously observed difference in optical depth measurements between all-source and RCG samples may largely be due to statistical fluctuations. These event rate measurements toward the central GB are necessary to predict the microlensing event rate and to optimize the survey fields in future space missions such as Wide Field Infrared Space Telescope.
- ID:
- ivo://CDS.VizieR/J/ApJS/244/29
- Title:
- Microlensing events toward the Galactic bulge
- Short Name:
- J/ApJS/244/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The number and properties of observed gravitational microlensing events depend on the distribution and kinematics of stars and other compact objects along the line of sight. In particular, precise measurements of the microlensing optical depth and event rate toward the Galactic bulge enable strict tests of competing models of the Milky Way. Previous estimates, based on samples of up to a few hundred events, gave larger values than expected from the Galactic models and were difficult to reconcile with other constraints on the Galactic structure. Here we used long-term photometric observations of the Galactic bulge by the Optical Gravitational Lensing Experiment (OGLE) to select a homogeneous sample of 8000 gravitational microlensing events. We created the largest and most accurate microlensing optical depth and event rate maps of the Galactic bulge. The new maps ease the tension between the previous measurements and Galactic models. They are consistent with some earlier calculations based on bright stars and are systematically ~30% smaller than the other estimates based on "all-source" samples of microlensing events. The difference is caused by the careful estimation of the source star population. The new maps agree well with predictions based on the Besancon model of the Galaxy. Apart from testing the Milky Way models, our maps may have numerous other applications, such as the measurement of the initial mass function or constraining the dark matter content in the Milky Way center. The new maps will also inform the planning of future space-based microlensing experiments by revising the expected number of events.
- ID:
- ivo://CDS.VizieR/J/ApJ/827/139
- Title:
- Microlensing optical depth & event rates from MOA-II
- Short Name:
- J/ApJ/827/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We find that significant incompleteness in stellar number counts results in a significant overestimate of the microlensing optical depth {tau} and event rate per star per year {Gamma} toward the Galactic bulge from the first two years of the MOA-II survey. We find that the completeness in red clump giant (RCG) counts f_RC_ decreases proportional to the galactic latitude b, as f_RC_=(0.63+/-0.11)-(0.052+/-0.028)xb, ranging between 1 and 0.7 at b=-6{deg}~-1.5{deg}. The previous measurements using all sources by difference image analysis (DIA) by MACHO and MOA-I suffer the same bias. On the other hand, the measurements using an RCG sample by OGLE-II, MACHO, and EROS were free from this bias because they selected only the events associated with the resolved stars. Thus, the incompleteness both in the number of events and stellar number count cancel out. We estimate {tau} and {Gamma} by correcting this incompleteness. In the central fields with |l|<5{deg}, we find {Gamma}=[18.74+/-0.91]x10^-6^exp[(0.53+/-0.05)(3-|b|)]/star/yr and {tau}_200_=[1.84+/-0.14]x10^-6^exp[(0.44+/-0.07)(3-|b|)] for the 427 events with t_E_<=200 days using all sources brighter than I_s_<=20mag. Our revised all-source {tau} measurements are about 2{sigma} smaller than the other all-source measurements and are consistent with the RCG measurements within 1{sigma}. We conclude that the long-standing problem on discrepancy between the high {tau} with all-source samples by DIA and low {tau} with RCG samples can probably be explained by the incompleteness of the stellar number count. A model fit to these measurements predicts {Gamma}=4.60+/-0.25x10^-5^/star/yr at |b|~-1.4{deg} and -2.25{deg}<l<3.75{deg} for sources with I<=20, where the future space mission, Wide Field Infrared Space Telescope, will observe.
- ID:
- ivo://CDS.VizieR/II/56
- Title:
- 100-Micron Survey of the Galactic Plane
- Short Name:
- II/56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog represents a survey of a portion of the galactic plane at a wavelength of 100 micrometers with a balloon-borne, stabilized, 12-inch infrared telescope having a sensitivity of 10(-22) W/m2/Hz. The survey covers 750 square degrees of the sky, including most of the galactic plane between galactic longitudes of 335 and 88 degrees, plus a number of other selected areas of interest. Seventy-two sources have been detected, 60 of which are identified with continuum radio sources, bright nebulae, dark nebulae, and infrared stars. The catalog includes right ascension and declination (B1950.0), galactic coordinates, 100-micrometer peak flux densities, sizes of sources, and identifications.
- ID:
- ivo://CDS.VizieR/J/ApJ/731/90
- Title:
- Mid-IR content of BGPS sources
- Short Name:
- J/ApJ/731/90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for mid-infrared signs of star formation activity in the 1.1mm sources in the Bolocam Galactic Plane Survey (BGPS). We have correlated the BGPS catalog (Cat. J/ApJS/188/123) with available mid-IR Galactic plane catalogs based on the Spitzer Space Telescope GLIMPSE legacy survey (including Cat. J/AJ/136/2413 and the EGO cat. J/AJ/136/2391) and the Midcourse Space Experiment (MSX) Galactic plane survey (RMS catalog, Hoare et al. 2004ASPC..317..156H). We find that 44% (3712 of 8358) of the BGPS sources contain at least one mid-IR source, including 2457 of 5067 (49%) within the area where all surveys overlap (10{deg}<l<65{deg}). Accounting for chance alignments between the BGPS and mid-IR sources, we conservatively estimate that 20% of the BPGS sources within the area where all surveys overlap show signs of active star formation. We separate the BGPS sources into four groups based on their probability of star formation activity. Extended Green Objects and Red MSX Sources make up the highest probability group, while the lowest probability group is comprised of "starless" BGPS sources which were not matched to any mid-IR sources. The mean 1.1mm flux of each group increases with increasing probability of active star formation.
- ID:
- ivo://CDS.VizieR/J/AJ/162/42
- Title:
- Milky Way Age-Metallicity-orbital energy relation
- Short Name:
- J/AJ/162/42
- Date:
- 21 Mar 2022 00:01:52
- Publisher:
- CDS
- Description:
- Globular clusters can form inside their host galaxies at high redshift when gas densities are higher and gas-rich mergers are common. They can also form inside lower-mass galaxies that have since been accreted and tidally disrupted, leaving their globular cluster complement bound to higher-mass halos. We argue that the age-metallicity-specific orbital energy relation in a galaxy's globular cluster system can be used to identify its origin. Gas-rich mergers should produce tightly bound systems in which metal-rich clusters are younger than metal-poor clusters. Globular clusters formed in massive disks and then scattered into a halo should have no relationship between age and specific orbital energy. Accreted globular clusters should produce weakly bound systems in which age and metallicity are correlated with eachother but inversely correlated with specific orbital energy. We use precise relative ages, self-consistent metallicities, and space-based proper motion-informed orbits to show that the Milky Way's metal-poor globular cluster system lies in a plane in age-metallicity-specific orbital energy space. We find that relatively young or metal-poor globular clusters are weakly bound to the Milky Way, while relatively old or metal-rich globular clusters are tightly bound to the Galaxy. While metal-rich globular clusters may be formed either in situ or ex situ, our results suggest that metal-poor clusters are formed outside of the Milky Way in now-disrupted dwarf galaxies. We predict that this relationship between age, metallicity, and specific orbital energy in a L* galaxy's globular cluster system is a natural outcome of galaxy formation in a {Lambda}CDM universe.
- ID:
- ivo://CDS.VizieR/J/AJ/118/895
- Title:
- Milky way and stellar distributions
- Short Name:
- J/AJ/118/895
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a photometric and spectroscopic study of stars in four fields toward the inner disk and Galactic bulge. The fields are located symmetrically about the minor axis of the Milky Way at (l, b)=(-24.8{deg}, -6.0{deg}), (-8.7{deg}, -6.0{deg}), (+8.4{deg}, -6.0{deg}), and (+24.4{deg}, -6.1{deg}). We measured radial velocities and strengths of selected absorption-line indexes and derived the average reddening to each field, individual metallicities and photometric parallaxes for each star, and mean azimuthal rotation velocities and velocity dispersions for each field.
- ID:
- ivo://CDS.VizieR/J/A+A/534/A94
- Title:
- Milky Way Cepheids radial velocities
- Short Name:
- J/A+A/534/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determine Period-Luminosity relations for Milky Way Cepheids in the optical and near-IR bands. These relations can be used directly as reference for extra-galactic distance determination to Cepheid populations with solar metallicity, and they form the basis for a direct comparison with relations obtained in exactly the same manner for stars in the Magellanic Clouds, presented in an accompanying paper. In that paper we show that the metallicity effect is very small and consistent with a null effect, particularly in the near-IR bands, and we combine here all 111 Cepheids from the Milky Way, the LMC and SMC to form a best relation. We employ the near-IR surface brightness (IRSB) method to determine direct distances to the individual Cepheids after we have recalibrated the projection factor using the recent parallax measurements to ten Galactic Cepheids and the constraint that Cepheid distances to the LMC should be independent of pulsation period. We confirm our earlier finding that the projection factor for converting radial velocity to pulsational velocity depends quite steeply on pulsation period, p=1.550-0.186*log(P) in disagrement with recent theoretical predictions. We find PL relations based on 70 Milky Way fundamental mode Cepheids of Mk=-3.33(+/-0.09)(log(P)-1.0)-5.66(+/-0.03), Wvi=-3.26(+/-0.11)(log(P)-1.0)-5.96(+/-0.04). Combining the 70 Cepheids presented here with the results for 41 Magellanic Cloud Cepheids which are presented in an accompanying paper, we find Mk=-3.30(+/-0.06)(log(P)-1.0)-5.65(+/-0.02), Wvi=-3.32(+/-0.08)(log(P)-1.0)-5.92(+/-0.03). We delineate the Cepheid PL relation using 111 Cepheids with direct distances from the IRSB analysis. The relations are by construction in agreement with the recent HST parallax distances to Cepheids and slopes are in excellent agreement with the slopes of apparent magnitudes versus period observed in the LMC.
