Solutions

Calculate the distance to each star

First define a function to convert from parallax to distance. Remember the input values will be in mas, and the formula needs arcsec:

def parallax_to_distance(parallax_mas):
    parallax_arcsec = parallax_mas * 1e-3
    distance = 1./parallax_arcsec
    return(distance)

Now use this to get the distance of each star:

cepheids_df['distance_pc'] = parallax_to_distance(cepheids_df['parallax_mas'])

cepheids_df

	Star_ID	parallax_mas	logP	mag_B	err_B	mag_V	err_V	mag_I	err_I	E_B_V	A_V	distance_pc
0	XX Cen	0.564	1.040	8.882	0.019	7.855	0.012	6.754	0.008	0.5223	1.6191	1773.049645
1	T Mon	0.733	1.432	7.436	0.022	6.187	0.014	5.005	0.010	0.5997	1.8590	1364.256480
2	TW Nor	0.362	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	2762.430939
3	CV Mon	0.602	0.731	11.681	0.015	10.314	0.010	8.653	0.006	1.4373	4.4556	1661.129568
4	RY Sco	0.754	1.308	9.568	0.018	8.037	0.012	6.271	0.008	1.2228	3.7907	1326.259947
5	TT Aql	0.994	1.138	8.560	0.022	7.185	0.014	5.745	0.009	0.9672	2.9983	1006.036217
6	QZ Nor	0.471	0.578	9.782	0.007	8.875	0.004	7.871	0.003	1.2364	3.8329	2123.142251
7	Y Oph	1.349	1.234	7.573	0.011	6.161	0.007	4.543	0.005	0.8138	2.5227	741.289844
8	VW Cen	0.256	1.177	11.754	0.022	10.306	0.014	8.802	0.009	1.3431	4.1638	3906.250000
9	V340 Nor	0.490	1.053	NaN	NaN	8.407	0.005	NaN	NaN	1.2831	3.9778	2040.816327
10	GY Sge	0.346	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	2890.173410
11	WZ Car	0.281	1.362	10.614	0.027	9.343	0.018	8.002	0.011	NaN	NaN	3558.718861
12	CD Cyg	0.393	1.232	10.422	0.025	9.023	0.016	7.525	0.010	NaN	NaN	2544.529262
13	FF Aql	1.920	0.650	6.159	0.007	5.383	0.005	4.503	0.004	0.4996	1.5486	520.833333
14	Y Lac	0.430	0.636	9.921	0.016	9.163	0.011	8.312	0.007	0.3880	1.2028	2325.581395
15	BB Sgr	1.194	0.822	7.987	0.013	6.965	0.008	5.855	0.006	0.2405	0.7455	837.520938
16	Z Lac	0.510	1.037	9.623	0.019	8.448	0.012	7.212	0.008	0.6702	2.0775	1960.784314
17	BG Lac	0.582	0.727	9.878	0.013	8.900	0.009	7.825	0.005	0.3374	1.0461	1718.213058
18	UU Mus	0.308	1.066	11.040	0.020	9.839	0.013	8.502	0.008	0.9659	2.9944	3246.753247
19	KN Cen	0.240	1.532	11.604	0.021	9.918	0.015	8.024	0.011	1.5576	4.8286	4166.666667
20	RU Sct	0.521	1.294	11.291	0.023	9.526	0.015	7.486	0.009	NaN	NaN	1919.385797
21	DL Cas	0.581	NaN	NaN	NaN	NaN	NaN	NaN	NaN	0.7936	2.4602	1721.170396
22	RS Pup	0.587	1.617	8.580	0.019	7.057	0.013	5.507	0.009	0.8197	2.5412	1703.577513
23	CE Cas B	0.331	NaN	NaN	NaN	NaN	NaN	NaN	NaN	0.8207	2.5440	3021.148036
24	SV Vul	0.405	1.653	8.810	0.018	7.267	0.012	5.719	0.009	NaN	NaN	2469.135802
25	VY Car	0.564	1.277	8.744	0.015	7.510	0.012	6.301	0.007	1.0360	3.2115	1773.049645
26	V367 Sct	0.470	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	2127.659574
27	U Nor	0.622	1.102	10.939	0.020	9.273	0.013	7.366	0.008	NaN	NaN	1607.717042
28	LS Pup	0.213	1.151	11.790	0.020	10.500	0.013	9.087	0.008	0.7634	2.3665	4694.835681
29	AQ Pup	0.290	1.479	10.197	0.022	8.756	0.015	7.178	0.010	0.7818	2.4236	3448.275862
...	...	...	...	...	...	...	...	...	...	...	...	...
37	CS Vel	0.274	0.771	13.071	0.017	11.728	0.011	10.080	0.007	1.9023	5.8970	3649.635036
38	V Cen	1.413	0.740	7.769	0.017	6.857	0.011	5.805	0.007	1.1718	3.6327	707.714084
39	CF Cas	0.315	NaN	NaN	NaN	NaN	NaN	NaN	NaN	0.8207	2.5440	3174.603175
40	T Vel	0.936	0.667	9.001	0.014	8.047	0.009	6.971	0.006	0.8183	2.5367	1068.376068
41	X Cyg	0.909	1.214	7.659	0.023	6.434	0.014	5.254	0.009	0.6879	2.1326	1100.110011
42	VZ Cyg	0.541	0.687	9.900	0.015	8.983	0.010	7.970	0.006	0.2543	0.7883	1848.428835
43	CE Cas A	0.331	NaN	NaN	NaN	NaN	NaN	NaN	NaN	0.8207	2.5440	3021.148036
44	SW Vel	0.409	1.370	9.435	0.022	8.189	0.014	6.875	0.009	0.9399	2.9137	2444.987775
45	SZ Aql	0.521	1.234	10.227	0.025	8.697	0.016	7.103	0.010	1.3786	4.2736	1919.385797
46	S Vul	0.231	NaN	NaN	NaN	NaN	NaN	NaN	NaN	1.9095	5.9195	4329.004329
47	RZ Vel	0.660	1.310	8.408	0.026	7.170	0.017	5.898	0.011	1.1769	3.6484	1515.151515
48	GH Lup	0.864	0.967	8.851	0.004	7.632	0.002	6.360	0.002	1.1761	3.6460	1157.407407
49	RY Vel	0.377	1.449	9.872	0.021	8.421	0.014	6.846	0.009	1.4953	4.6355	2652.519894
50	X Sgr	2.822	0.846	5.334	0.013	4.569	0.009	3.663	0.006	NaN	NaN	354.358611
51	V496 Aql	0.976	0.833	8.937	0.008	7.769	0.005	6.491	0.004	0.3182	0.9863	1024.590164
52	V350 Sgr	0.806	0.712	8.449	0.015	7.504	0.010	6.453	0.006	0.3277	1.0158	1240.694789
53	U Vul	1.291	0.903	8.492	0.016	7.149	0.011	5.609	0.007	NaN	NaN	774.593338
54	W Sgr	2.354	0.881	5.472	0.017	4.694	0.011	3.863	0.007	0.5578	1.7292	424.808836
55	SU Cyg	1.036	0.585	7.493	0.015	6.890	0.011	6.208	0.007	0.9989	3.0967	965.250965
56	S Sge	1.685	0.923	6.488	0.016	5.641	0.011	4.782	0.006	0.2888	0.8953	593.471810
57	beta Dor	2.917	0.993	4.586	0.013	3.758	0.009	2.946	0.006	0.0539	0.1669	342.817964
58	U Car	0.559	1.589	7.625	0.025	6.342	0.016	5.076	0.010	NaN	NaN	1788.908766
59	l Car	1.942	1.551	5.048	0.017	3.749	0.011	2.564	0.007	0.2190	0.6788	514.933059
60	zeta Gem	3.064	1.007	4.735	0.011	3.901	0.007	3.100	0.005	0.0699	0.2166	326.370757
61	Y Sgr	2.003	0.761	6.657	0.016	5.766	0.010	4.801	0.006	1.7647	5.4707	499.251123
62	delta Cep	3.556	0.730	4.684	0.018	3.990	0.012	NaN	NaN	1.4914	4.6233	281.214848
63	U Aql	1.748	0.847	7.536	0.016	6.457	0.011	5.279	0.007	0.3334	1.0337	572.082380
64	eta Aql	3.674	0.856	4.744	0.017	3.918	0.011	3.036	0.007	0.1936	0.6001	272.182907
65	RT Aur	1.841	0.571	6.120	0.017	5.487	0.011	4.822	0.006	0.1844	0.5717	543.183053
66	SU Cru	0.211	1.109	11.613	0.015	9.802	0.008	7.658	0.003	NaN	NaN	4739.336493

67 rows × 12 columns

Calculate the extinction

First set up an array with the wavelengths:

wavelengths = [0.445, 0.806]
## Don't need V as we already know A_V

Now define the function to get $A_{\lambda}/A_V$

def extinction(wavelength, A_V):
    A_l_A_V = (0.7 / wavelength) - 0.273
    A_l = A_l_A_V * A_V
    return(A_l)

Now find the $A_B$ and $A_I$ values:

cepheids_df['A_B'] = extinction(wavelengths[0], cepheids_df['A_V'])
cepheids_df['A_I'] = extinction(wavelengths[1], cepheids_df['A_V'])

cepheids_df

	Star_ID	parallax_mas	logP	mag_B	err_B	mag_V	err_V	mag_I	err_I	E_B_V	A_V	distance_pc	A_B	A_I
0	XX Cen	0.564	1.040	8.882	0.019	7.855	0.012	6.754	0.008	0.5223	1.6191	1773.049645	2.104885	0.964152
1	T Mon	0.733	1.432	7.436	0.022	6.187	0.014	5.005	0.010	0.5997	1.8590	1364.256480	2.416763	1.107009
2	TW Nor	0.362	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	2762.430939	NaN	NaN
3	CV Mon	0.602	0.731	11.681	0.015	10.314	0.010	8.653	0.006	1.4373	4.4556	1661.129568	5.792430	2.653249
4	RY Sco	0.754	1.308	9.568	0.018	8.037	0.012	6.271	0.008	1.2228	3.7907	1326.259947	4.928038	2.257310
5	TT Aql	0.994	1.138	8.560	0.022	7.185	0.014	5.745	0.009	0.9672	2.9983	1006.036217	3.897891	1.785447
6	QZ Nor	0.471	0.578	9.782	0.007	8.875	0.004	7.871	0.003	1.2364	3.8329	2123.142251	4.982899	2.282440
7	Y Oph	1.349	1.234	7.573	0.011	6.161	0.007	4.543	0.005	0.8138	2.5227	741.289844	3.279595	1.502233
8	VW Cen	0.256	1.177	11.754	0.022	10.306	0.014	8.802	0.009	1.3431	4.1638	3906.250000	5.413080	2.479486
9	V340 Nor	0.490	1.053	NaN	NaN	8.407	0.005	NaN	NaN	1.2831	3.9778	2040.816327	5.171274	2.368726
10	GY Sge	0.346	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	2890.173410	NaN	NaN
11	WZ Car	0.281	1.362	10.614	0.027	9.343	0.018	8.002	0.011	NaN	NaN	3558.718861	NaN	NaN
12	CD Cyg	0.393	1.232	10.422	0.025	9.023	0.016	7.525	0.010	NaN	NaN	2544.529262	NaN	NaN
13	FF Aql	1.920	0.650	6.159	0.007	5.383	0.005	4.503	0.004	0.4996	1.5486	520.833333	2.013232	0.922170
14	Y Lac	0.430	0.636	9.921	0.016	9.163	0.011	8.312	0.007	0.3880	1.2028	2325.581395	1.563681	0.716251
15	BB Sgr	1.194	0.822	7.987	0.013	6.965	0.008	5.855	0.006	0.2405	0.7455	837.520938	0.969175	0.443935
16	Z Lac	0.510	1.037	9.623	0.019	8.448	0.012	7.212	0.008	0.6702	2.0775	1960.784314	2.700820	1.237123
17	BG Lac	0.582	0.727	9.878	0.013	8.900	0.009	7.825	0.005	0.3374	1.0461	1718.213058	1.359965	0.622938
18	UU Mus	0.308	1.066	11.040	0.020	9.839	0.013	8.502	0.008	0.9659	2.9944	3246.753247	3.892821	1.783124
19	KN Cen	0.240	1.532	11.604	0.021	9.918	0.015	8.024	0.011	1.5576	4.8286	4166.666667	6.277343	2.875365
20	RU Sct	0.521	1.294	11.291	0.023	9.526	0.015	7.486	0.009	NaN	NaN	1919.385797	NaN	NaN
21	DL Cas	0.581	NaN	NaN	NaN	NaN	NaN	NaN	NaN	0.7936	2.4602	1721.170396	3.198343	1.465016
22	RS Pup	0.587	1.617	8.580	0.019	7.057	0.013	5.507	0.009	0.8197	2.5412	1703.577513	3.303646	1.513250
23	CE Cas B	0.331	NaN	NaN	NaN	NaN	NaN	NaN	NaN	0.8207	2.5440	3021.148036	3.307286	1.514917
24	SV Vul	0.405	1.653	8.810	0.018	7.267	0.012	5.719	0.009	NaN	NaN	2469.135802	NaN	NaN
25	VY Car	0.564	1.277	8.744	0.015	7.510	0.012	6.301	0.007	1.0360	3.2115	1773.049645	4.175058	1.912404
26	V367 Sct	0.470	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	2127.659574	NaN	NaN
27	U Nor	0.622	1.102	10.939	0.020	9.273	0.013	7.366	0.008	NaN	NaN	1607.717042	NaN	NaN
28	LS Pup	0.213	1.151	11.790	0.020	10.500	0.013	9.087	0.008	0.7634	2.3665	4694.835681	3.076530	1.409218
29	AQ Pup	0.290	1.479	10.197	0.022	8.756	0.015	7.178	0.010	0.7818	2.4236	3448.275862	3.150762	1.443221
...	...	...	...	...	...	...	...	...	...	...	...	...	...	...
37	CS Vel	0.274	0.771	13.071	0.017	11.728	0.011	10.080	0.007	1.9023	5.8970	3649.635036	7.666299	3.511583
38	V Cen	1.413	0.740	7.769	0.017	6.857	0.011	5.805	0.007	1.1718	3.6327	707.714084	4.722632	2.163223
39	CF Cas	0.315	NaN	NaN	NaN	NaN	NaN	NaN	NaN	0.8207	2.5440	3174.603175	3.307286	1.514917
40	T Vel	0.936	0.667	9.001	0.014	8.047	0.009	6.971	0.006	0.8183	2.5367	1068.376068	3.297796	1.510570
41	X Cyg	0.909	1.214	7.659	0.023	6.434	0.014	5.254	0.009	0.6879	2.1326	1100.110011	2.772452	1.269934
42	VZ Cyg	0.541	0.687	9.900	0.015	8.983	0.010	7.970	0.006	0.2543	0.7883	1848.428835	1.024817	0.469422
43	CE Cas A	0.331	NaN	NaN	NaN	NaN	NaN	NaN	NaN	0.8207	2.5440	3021.148036	3.307286	1.514917
44	SW Vel	0.409	1.370	9.435	0.022	8.189	0.014	6.875	0.009	0.9399	2.9137	2444.987775	3.787908	1.735069
45	SZ Aql	0.521	1.234	10.227	0.025	8.697	0.016	7.103	0.010	1.3786	4.2736	1919.385797	5.555824	2.544870
46	S Vul	0.231	NaN	NaN	NaN	NaN	NaN	NaN	NaN	1.9095	5.9195	4329.004329	7.695550	3.524981
47	RZ Vel	0.660	1.310	8.408	0.026	7.170	0.017	5.898	0.011	1.1769	3.6484	1515.151515	4.743043	2.172572
48	GH Lup	0.864	0.967	8.851	0.004	7.632	0.002	6.360	0.002	1.1761	3.6460	1157.407407	4.739923	2.171143
49	RY Vel	0.377	1.449	9.872	0.021	8.421	0.014	6.846	0.009	1.4953	4.6355	2652.519894	6.026306	2.760377
50	X Sgr	2.822	0.846	5.334	0.013	4.569	0.009	3.663	0.006	NaN	NaN	354.358611	NaN	NaN
51	V496 Aql	0.976	0.833	8.937	0.008	7.769	0.005	6.491	0.004	0.3182	0.9863	1024.590164	1.282223	0.587328
52	V350 Sgr	0.806	0.712	8.449	0.015	7.504	0.010	6.453	0.006	0.3277	1.0158	1240.694789	1.320574	0.604895
53	U Vul	1.291	0.903	8.492	0.016	7.149	0.011	5.609	0.007	NaN	NaN	774.593338	NaN	NaN
54	W Sgr	2.354	0.881	5.472	0.017	4.694	0.011	3.863	0.007	0.5578	1.7292	424.808836	2.248018	1.029715
55	SU Cyg	1.036	0.585	7.493	0.015	6.890	0.011	6.208	0.007	0.9989	3.0967	965.250965	4.025814	1.844043
56	S Sge	1.685	0.923	6.488	0.016	5.641	0.011	4.782	0.006	0.2888	0.8953	593.471810	1.163920	0.533139
57	beta Dor	2.917	0.993	4.586	0.013	3.758	0.009	2.946	0.006	0.0539	0.1669	342.817964	0.216976	0.099387
58	U Car	0.559	1.589	7.625	0.025	6.342	0.016	5.076	0.010	NaN	NaN	1788.908766	NaN	NaN
59	l Car	1.942	1.551	5.048	0.017	3.749	0.011	2.564	0.007	0.2190	0.6788	514.933059	0.882463	0.404216
60	zeta Gem	3.064	1.007	4.735	0.011	3.901	0.007	3.100	0.005	0.0699	0.2166	326.370757	0.281587	0.128982
61	Y Sgr	2.003	0.761	6.657	0.016	5.766	0.010	4.801	0.006	1.7647	5.4707	499.251123	7.112094	3.257727
62	delta Cep	3.556	0.730	4.684	0.018	3.990	0.012	NaN	NaN	1.4914	4.6233	281.214848	6.010446	2.753112
63	U Aql	1.748	0.847	7.536	0.016	6.457	0.011	5.279	0.007	0.3334	1.0337	572.082380	1.343845	0.615554
64	eta Aql	3.674	0.856	4.744	0.017	3.918	0.011	3.036	0.007	0.1936	0.6001	272.182907	0.780150	0.357351
65	RT Aur	1.841	0.571	6.120	0.017	5.487	0.011	4.822	0.006	0.1844	0.5717	543.183053	0.743229	0.340440
66	SU Cru	0.211	1.109	11.613	0.015	9.802	0.008	7.658	0.003	NaN	NaN	4739.336493	NaN	NaN

67 rows × 14 columns

Use apply to find the $B$ and $I$ absolute magnitudes

cepheids_df['B_abs'] = cepheids_df.apply(lambda x: abs_mag(x.mag_B, x.A_B, dist_mod(x.distance_pc)), axis=1)
cepheids_df['I_abs'] = cepheids_df.apply(lambda x: abs_mag(x.mag_I, x.A_I, dist_mod(x.distance_pc)), axis=1)

cepheids_df

	Star_ID	parallax_mas	logP	mag_B	err_B	mag_V	err_V	mag_I	err_I	E_B_V	A_V	distance_pc	A_B	A_I	V_abs	B_abs	I_abs
0	XX Cen	0.564	1.040	8.882	0.019	7.855	0.012	6.754	0.008	0.5223	1.6191	1773.049645	2.104885	0.964152	-5.007704	-4.466489	-5.453756
1	T Mon	0.733	1.432	7.436	0.022	6.187	0.014	5.005	0.010	0.5997	1.8590	1364.256480	2.416763	1.107009	-6.346480	-5.655243	-6.776489
2	TW Nor	0.362	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	2762.430939	NaN	NaN	NaN	NaN	NaN
3	CV Mon	0.602	0.731	11.681	0.015	10.314	0.010	8.653	0.006	1.4373	4.4556	1661.129568	5.792430	2.653249	-5.243618	-5.213448	-5.102267
4	RY Sco	0.754	1.308	9.568	0.018	8.037	0.012	6.271	0.008	1.2228	3.7907	1326.259947	4.928038	2.257310	-6.366843	-5.973181	-6.599453
5	TT Aql	0.994	1.138	8.560	0.022	7.185	0.014	5.745	0.009	0.9672	2.9983	1006.036217	3.897891	1.785447	-5.826368	-5.350959	-6.053515
6	QZ Nor	0.471	0.578	9.782	0.007	8.875	0.004	7.871	0.003	1.2364	3.8329	2123.142251	4.982899	2.282440	-6.592795	-6.835795	-6.046335
7	Y Oph	1.349	1.234	7.573	0.011	6.161	0.007	4.543	0.005	0.8138	2.5227	741.289844	3.279595	1.502233	-5.711640	-5.056535	-6.309174
8	VW Cen	0.256	1.177	11.754	0.022	10.306	0.014	8.802	0.009	1.3431	4.1638	3906.250000	5.413080	2.479486	-6.816600	-6.617881	-6.636286
9	V340 Nor	0.490	1.053	NaN	NaN	8.407	0.005	NaN	NaN	1.2831	3.9778	2040.816327	5.171274	2.368726	-7.119820	NaN	NaN
10	GY Sge	0.346	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	2890.173410	NaN	NaN	NaN	NaN	NaN
11	WZ Car	0.281	1.362	10.614	0.027	9.343	0.018	8.002	0.011	NaN	NaN	3558.718861	NaN	NaN	NaN	NaN	NaN
12	CD Cyg	0.393	1.232	10.422	0.025	9.023	0.016	7.525	0.010	NaN	NaN	2544.529262	NaN	NaN	NaN	NaN	NaN
13	FF Aql	1.920	0.650	6.159	0.007	5.383	0.005	4.503	0.004	0.4996	1.5486	520.833333	2.013232	0.922170	-4.749094	-4.437726	-5.002664
14	Y Lac	0.430	0.636	9.921	0.016	9.163	0.011	8.312	0.007	0.3880	1.2028	2325.581395	1.563681	0.716251	-3.872458	-3.475338	-4.236909
15	BB Sgr	1.194	0.822	7.987	0.013	6.965	0.008	5.855	0.006	0.2405	0.7455	837.520938	0.969175	0.443935	-3.395478	-2.597153	-4.203913
16	Z Lac	0.510	1.037	9.623	0.019	8.448	0.012	7.212	0.008	0.6702	2.0775	1960.784314	2.700820	1.237123	-5.091649	-4.539969	-5.487272
17	BG Lac	0.582	0.727	9.878	0.013	8.900	0.009	7.825	0.005	0.3374	1.0461	1718.213058	1.359965	0.622938	-3.321485	-2.657350	-3.973323
18	UU Mus	0.308	1.066	11.040	0.020	9.839	0.013	8.502	0.008	0.9659	2.9944	3246.753247	3.892821	1.783124	-5.712646	-5.410067	-5.838371
19	KN Cen	0.240	1.532	11.604	0.021	9.918	0.015	8.024	0.011	1.5576	4.8286	4166.666667	6.277343	2.875365	-8.009544	-7.772287	-7.950309
20	RU Sct	0.521	1.294	11.291	0.023	9.526	0.015	7.486	0.009	NaN	NaN	1919.385797	NaN	NaN	NaN	NaN	NaN
21	DL Cas	0.581	NaN	NaN	NaN	NaN	NaN	NaN	NaN	0.7936	2.4602	1721.170396	3.198343	1.465016	NaN	NaN	NaN
22	RS Pup	0.587	1.617	8.580	0.019	7.057	0.013	5.507	0.009	0.8197	2.5412	1703.577513	3.303646	1.513250	-6.641009	-5.880455	-7.163059
23	CE Cas B	0.331	NaN	NaN	NaN	NaN	NaN	NaN	NaN	0.8207	2.5440	3021.148036	3.307286	1.514917	NaN	NaN	NaN
24	SV Vul	0.405	1.653	8.810	0.018	7.267	0.012	5.719	0.009	NaN	NaN	2469.135802	NaN	NaN	NaN	NaN	NaN
25	VY Car	0.564	1.277	8.744	0.015	7.510	0.012	6.301	0.007	1.0360	3.2115	1773.049645	4.175058	1.912404	-6.945104	-6.674663	-6.855009
26	V367 Sct	0.470	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	2127.659574	NaN	NaN	NaN	NaN	NaN
27	U Nor	0.622	1.102	10.939	0.020	9.273	0.013	7.366	0.008	NaN	NaN	1607.717042	NaN	NaN	NaN	NaN	NaN
28	LS Pup	0.213	1.151	11.790	0.020	10.500	0.013	9.087	0.008	0.7634	2.3665	4694.835681	3.076530	1.409218	-5.224602	-4.644632	-5.680320
29	AQ Pup	0.290	1.479	10.197	0.022	8.756	0.015	7.178	0.010	0.7818	2.4236	3448.275862	3.150762	1.443221	-6.355610	-5.641772	-6.953231
...	...	...	...	...	...	...	...	...	...	...	...	...	...	...	...	...	...
37	CS Vel	0.274	0.771	13.071	0.017	11.728	0.011	10.080	0.007	1.9023	5.8970	3649.635036	7.666299	3.511583	-6.980247	-7.406546	-6.242830
38	V Cen	1.413	0.740	7.769	0.017	6.857	0.011	5.805	0.007	1.1718	3.6327	707.714084	4.722632	2.163223	-6.024989	-6.202922	-5.607512
39	CF Cas	0.315	NaN	NaN	NaN	NaN	NaN	NaN	NaN	0.8207	2.5440	3174.603175	3.307286	1.514917	NaN	NaN	NaN
40	T Vel	0.936	0.667	9.001	0.014	8.047	0.009	6.971	0.006	0.8183	2.5367	1068.376068	3.297796	1.510570	-4.633321	-4.440416	-4.683191
41	X Cyg	0.909	1.214	7.659	0.023	6.434	0.014	5.254	0.009	0.6879	2.1326	1100.110011	2.772452	1.269934	-5.905781	-5.320632	-6.223115
42	VZ Cyg	0.541	0.687	9.900	0.015	8.983	0.010	7.970	0.006	0.2543	0.7883	1848.428835	1.024817	0.469422	-3.139314	-2.458830	-3.833436
43	CE Cas A	0.331	NaN	NaN	NaN	NaN	NaN	NaN	NaN	0.8207	2.5440	3021.148036	3.307286	1.514917	NaN	NaN	NaN
44	SW Vel	0.409	1.370	9.435	0.022	8.189	0.014	6.875	0.009	0.9399	2.9137	2444.987775	3.787908	1.735069	-6.666083	-6.294292	-6.801452
45	SZ Aql	0.521	1.234	10.227	0.025	8.697	0.016	7.103	0.010	1.3786	4.2736	1919.385797	5.555824	2.544870	-6.992411	-6.744635	-6.857682
46	S Vul	0.231	NaN	NaN	NaN	NaN	NaN	NaN	NaN	1.9095	5.9195	4329.004329	7.695550	3.524981	NaN	NaN	NaN
47	RZ Vel	0.660	1.310	8.408	0.026	7.170	0.017	5.898	0.011	1.1769	3.6484	1515.151515	4.743043	2.172572	-7.380680	-7.237323	-7.176853
48	GH Lup	0.864	0.967	8.851	0.004	7.632	0.002	6.360	0.002	1.1761	3.6460	1157.407407	4.739923	2.171143	-6.331431	-6.206354	-6.128575
49	RY Vel	0.377	1.449	9.872	0.021	8.421	0.014	6.846	0.009	1.4953	4.6355	2652.519894	6.026306	2.760377	-8.332793	-8.272600	-8.032670
50	X Sgr	2.822	0.846	5.334	0.013	4.569	0.009	3.663	0.006	NaN	NaN	354.358611	NaN	NaN	NaN	NaN	NaN
51	V496 Aql	0.976	0.833	8.937	0.008	7.769	0.005	6.491	0.004	0.3182	0.9863	1024.590164	1.282223	0.587328	-3.270051	-2.397974	-4.149079
52	V350 Sgr	0.806	0.712	8.449	0.015	7.504	0.010	6.453	0.006	0.3277	1.0158	1240.694789	1.320574	0.604895	-3.980125	-3.339899	-4.620220
53	U Vul	1.291	0.903	8.492	0.016	7.149	0.011	5.609	0.007	NaN	NaN	774.593338	NaN	NaN	NaN	NaN	NaN
54	W Sgr	2.354	0.881	5.472	0.017	4.694	0.011	3.863	0.007	0.5578	1.7292	424.808836	2.248018	1.029715	-5.176168	-4.916986	-5.307683
55	SU Cyg	1.036	0.585	7.493	0.015	6.890	0.011	6.208	0.007	0.9989	3.0967	965.250965	4.025814	1.844043	-6.129901	-6.456016	-5.559244
56	S Sge	1.685	0.923	6.488	0.016	5.641	0.011	4.782	0.006	0.2888	0.8953	593.471810	1.163920	0.533139	-4.121300	-3.542921	-4.618139
57	beta Dor	2.917	0.993	4.586	0.013	3.758	0.009	2.946	0.006	0.0539	0.1669	342.817964	0.216976	0.099387	-4.084218	-3.306293	-4.828705
58	U Car	0.559	1.589	7.625	0.025	6.342	0.016	5.076	0.010	NaN	NaN	1788.908766	NaN	NaN	NaN	NaN	NaN
59	l Car	1.942	1.551	5.048	0.017	3.749	0.011	2.564	0.007	0.2190	0.6788	514.933059	0.882463	0.404216	-5.488554	-4.393217	-6.398970
60	zeta Gem	3.064	1.007	4.735	0.011	3.901	0.007	3.100	0.005	0.0699	0.2166	326.370757	0.281587	0.128982	-3.884156	-3.115143	-4.597539
61	Y Sgr	2.003	0.761	6.657	0.016	5.766	0.010	4.801	0.006	1.7647	5.4707	499.251123	7.112094	3.257727	-8.196295	-8.946690	-6.948322
62	delta Cep	3.556	0.730	4.684	0.018	3.990	0.012	NaN	NaN	1.4914	4.6233	281.214848	6.010446	2.753112	-7.878491	-8.571637	NaN
63	U Aql	1.748	0.847	7.536	0.016	6.457	0.011	5.279	0.007	0.3334	1.0337	572.082380	1.343845	0.615554	-3.363993	-2.595138	-4.123847
64	eta Aql	3.674	0.856	4.744	0.017	3.918	0.011	3.036	0.007	0.1936	0.6001	272.182907	0.780150	0.357351	-3.856404	-3.210454	-4.495656
65	RT Aur	1.841	0.571	6.120	0.017	5.487	0.011	4.822	0.006	0.1844	0.5717	543.183053	0.743229	0.340440	-3.759431	-3.297960	-4.193171
66	SU Cru	0.211	1.109	11.613	0.015	9.802	0.008	7.658	0.003	NaN	NaN	4739.336493	NaN	NaN	NaN	NaN	NaN

67 rows × 17 columns

Save your data!

This bit isn't hard. Well done for making it to the end!

cepheids_df.to_csv('./data/big_cepheids_file_with_extinctions_and_distances_and_whathaveyou.csv', index=False, float_format='%.4f', na_rep='NaN')