Magellanic System in OGLE-IV

OGLE-ing the Magellanic System: 3-D Structure of the Clouds and the Bridge using Classical Cepheids

A. M. Jacyszyn-Dobrzeniecka, D. M. Skowron, P. Mróz, J. Skowron, I. Soszyński, A. Udalski, P. Pietrukowicz, S. Kozłowski,
Ł. Wyrzykowski, R. Poleski, M. Pawlak, M. K. Szymański, K. Ulaczyk
2016, arXiv:1602.09141

We analyzed a sample of 9418 fundamental-mode and first-overtone Classical Cepheids from the OGLE-IV Collection of Classical Cepheids. The distance to each Cepheid was calculated using the period-luminosity relation for the Wesenheit magnitude, fitted to our data.

Classical Cepheids in the Magellanic System

The Classical Cepheids in the LMC are situated mainly in the bar and in the northern arm. The eastern part of the LMC is closer to us and the plane fit to the whole LMC sample yields the inclination i = 24.°2±0.°6 and position angle P.A. = 151.°4±.°5. We redefined the LMC bar by extending it in the western direction and found no offset from the plane of the LMC contrary to previous studies. On the other hand, we found that the northern arm is offset from a plane by about -0.5 kpc, which was not observed before. The age distribution of the LMC Cepheids shows one maximum at about 100 Myr.

Classical Cepheids in the Large Magellanic Cloud

We demonstrate that the SMC has a non-planar structure and can be described as an extended ellipsoid. We identified two large ellipsoidal off-axis structures in the SMC. The northern one is located closer to us and is younger, while the south-western is farther and older. The age distribution of the SMC Cepheids is bimodal with one maximum at 110 Myr, and another one at 220 Myr. Younger stars are located in the closer part of this galaxy while older ones are more distant.

Classical Cepheids in the Small Magellanic Cloud

We classified nine Cepheids from our sample as Magellanic Bridge objects. These Cepheids show a large spread in three-dimensions although five of them form a connection between the Clouds. The closest one is closer than any of the LMC Cepheids, while the farthest one - farther than any SMC Cepheid. All but one Cepheids in the Magellanic Bridge are younger than 300 Myr. The oldest one can be associated with the SMC Wing.

Classical Cepheids in the Magellanic Bridge

Computer readable Table 3 from the Paper is available for download here: table3.dat

Location OCVS_Id P.mode P I V WI,V-I R.A. Dec d x y z Age
[d] [mag] [mag] [mag] [h] [deg] [kpc] [kpc] [kpc] [kpc] [Myr]
LMC OGLE-LMC-CEP-0004 1O 2.2296385 15.123 15.690 14.244 04:35:20.16 -69:48:07.7 51.03 1.40 -5.69 0.43 1.06 0.85 50.70 1.50 102 19
LMC OGLE-LMC-CEP-0005 F 5.6119491 14.651 15.425 13.451 04:35:31.52 -69:44:05.8 51.05 1.41 -5.72 0.43 1.11 0.85 50.72 1.50 66 15
LMC OGLE-LMC-CEP-0006 1O 3.2947501 14.707 15.366 13.686 04:35:42.16 -69:43:29.1 51.51 1.42 -5.79 0.43 1.13 0.86 51.18 1.51 75 14
LMC OGLE-LMC-CEP-0007 1O 0.7090827 16.955 17.561 16.016 04:36:30.06 -68:37:35.7 52.77 1.45 -6.30 0.46 2.10 0.88 52.35 1.55 256 47
LMC OGLE-LMC-CEP-0008 1O/2O 0.9728732 16.337 16.921 15.432 04:36:33.08 -69:18:43.6 50.05 1.38 -5.80 0.43 1.42 0.84 49.69 1.47 199 36
LMC OGLE-LMC-CEP-0009 1O 2.0243667 15.433 16.130 14.353 04:36:52.13 -68:03:51.3 50.22 1.38 -6.18 0.44 2.45 0.84 49.78 1.48 110 20
see whole Table

PLEASE cite the following paper when using the data or referring to these OGLE results:
Jacyszyn-Dobrzeniecka et al., 2016, Acta Astron, 66, 149, arXiv:1602.09141

Any comments about the data and the form of their presentation are welcome as they can improve the future releases of OGLE analysis. Send your messages to this address.