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Magellanic System in OGLE-IV

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

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.

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.

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.

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.

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

• P - for multi-mode Cepheids the longest period is provided
• d - distance from the observer
• x,y,z - the cartesian coordinates
• Age - calculated using PA relations from Bono et al. (2005)

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.

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