16413+3136 STF 2084 (Zet Her)

Coord 2000	16413+3136		Discov num	STF2084		Comp			Coord arcsec 2000	16 41 17.16 +31 36 09.8
Date first	1826		Date last	2019		Obs	862
Pa first	23		Pa last	110.3		P.A. Now (θ)	90.4°
Sep first	0.9		Sep last	1.63		Sep. Now (ρ)	1.53"
Mag pri	2.95		Mag sec	5.40		delta mag (ΔM)	2.45		Spectral class	G1IV (yellow)
Pri motion ra	-463		Sec motion ra
Pri motion dec	+345		Sec motion dec
Notes	N O (See Notes, Orbital solution)

This double is physical.

Name	Zet Her		Var name	NSV7915 Her		Constellation	Hercules		SAO	65485
HIP	81693		Tycho2	2582-03158-1		HD	150680		HR	6212
GC	22464		ADS	10157		GL	Gl 635A		BD	BD+31 2884
Bayer	Zeta Herculis		Bayer name	Zet Her		Flamsteed	40 Herculis		Flamsteed name	40 Her
Distance	10.72		Distance ly	34.97		Bayer greek	ζ Her

Period (P)	34.4638y	± 0.0251	Periastron (T)	1933.3518y	± 0.0492	Semi-major axis (a)	1.32834a	± 0.00807
Eccentricity (e)	0.46342	± 0.00417	Inclination (i)	131.6°	± 0.578	Longitude of periastron (ω)	113.177°	± 0.803
Node (Ω)	50.601°	± 0.746	Notes	n		Reference	Izm2019
Equinox			Last observation	2015		Grade	1	(1=Definitive, 9=Indet.)

label theta rho 2000 12.9 0.714 2001 343.9 0.533 2002 299.7 0.493 2003 263.3 0.624 2004 241.4 0.789 2005 226.5 0.915 2006 214.7 0.997 2007 204.4 1.046 2008 194.8 1.075 2009 185.6 1.094 2010 176.6 1.108 2011 167.9 1.124 2012 159.4 1.142 2013 151.3 1.166 2014 143.5 1.194 2015 136.1 1.228 2016 129.1 1.265 2017 122.6 1.306 2018 116.4 1.348 2019 110.6 1.391 2020 105.2 1.431 2021 100.0 1.469 2022 95.1 1.503 2023 90.4 1.530 2024 85.8 1.549 2025 81.3 1.559 2026 76.9 1.557 2027 72.4 1.542 2028 67.7 1.511 2029 62.8 1.461 2030 57.5 1.389		Note: Theta is PA, Rho is Sep. For yearly orbits, data refer to Jan 1st.
		Measures: green=micrometric, blue=interferometric, purple=photographic

discov_num	notes	refcode
STF2084	zet Her = 40 Her.
	Mk III Limb-darkened diameter 2.33 +/- 0.05 mas.	MkT2001
	Mk III Limb-darkened diameter 2.367 +/- 0.051 mas.	MkT2003
	NPOI Limb-darkened diameter 2.49 +/- 0.09 mas.	NOI2001b
	Berman (1941) has discussed the RV's.	Ber1941
	A subsystem with a period of about 12 yr has repeatedly been
	suspected (cf Baize 1976), and the third component has now been	Baz1976
	detected by infrared speckle interferometry.	Mcy1983
	No evidence in the speckle or Hipparcos data for the large-amplitude
	third-body orbit given by Baize.
	See Baize & Petit (1989) catalog of doubles with variable component.	Baz1989d
	Giant primary according to isochrone fit.	Sod1999
	H 1 36.	MEv2010
	Malkov et al. (2012) derive dynamical, photometric, and spectroscopic
	masses of 2.44 +/- 1.31, 2.12, and 1.26 Msun, respectively.	Mlk2012

refcode	metd	author	reference
Baz1976	orb -	Baize, P.	1976A&AS...26..177B
Baz1976		A&AS 26, 177, 1976
Baz1989d	-	Baize, P. & Petit, M.	1989A&AS...77..497B
Baz1989d		A&AS 77, 497, 1989
Ber1941	-	Berman, L.	1941PASP...53...22B
Ber1941		PASP 53, 22, 1941
Izm2019	orb u	Izmailov, I.S.	2019AstL...45...30I
Izm2019		Ast. Lett. 45, 30, 2019
Izm2019		(Orbital elements from weighted solutions used when available (Table 2),
Izm2019		unweighted elements (Table 1) used for remaining 29 systems.)
Mcy1983	Si -	McCarthy, D.W.	1983nssl.conf..107M
Mcy1983	+C	IAU Colloq 76, 107, 1983
MEv2010	-	MacEvoy, B.	...................
MEv2010		private communication, 2010 (see http://www.handprint.com/ASTRO/index.html)
MkT2001	not j	Nordgren, T.E., Sudol, J.J. & Mozurkewich, D.	2001AJ....122.2707N
MkT2001		AJ 122, 2707, 2001	.
MkT2003	Km -	Mozurkewich, D., Armstrong, J.T., Hindsley, R., Quirrenbach, A., Hummel, C.A.,	2003AJ....126.2502M
MkT2003	+not	Hutter, D., Johnston, K.J., Hajian, A., Elias, N.M., II, Buscher, D., & Simon, R.
MkT2003		AJ 126, 2502, 2003
Mlk2012	not -	Malkov, O.Yu., Tamazian, V.S., Docobo, J.A., & Chulkov, D.A.	2012A&A...546A..69M
Mlk2012		A&A 546, A69, 2012
NOI2001b	not j	Nordgren, T.E., Sudol, J.J. & Mozurkewich, D.	2001AJ....122.2707N
NOI2001b		AJ 122, 2707, 2001	.
Sod1999	orb -	Soderhjelm, S.	1999A&A...341..121S
Sod1999		A&A 341, 121, 1999

idgroup	discov	author
1	STF	Struve, F.G.W.

coord_2000	discov_num	comp	epoch	obs	pa	sep	mag_pri	mag_sec	spectr	notes	coord_arcsec_2000
16413+3136	STF2084		2007	807	198	1.1	2.95	5.40	G1IV	NOD	164117.46+313607.0
16413+3136	STF2084		2008	813	185	1.2	2.95	5.40	G1IV	NOD	164117.46+313607.0
16413+3136	STF2084		2010	819	173	1.1	2.95	5.40	G1IV	NOD	164117.46+313607.0
16413+3136	STF2084		2011	824	166	1.3	2.95	5.40	G1IV	NOD	164117.46+313607.0
16413+3136	STF2084		2013	835	149	1.3	2.95	5.40	G1IV	NOD	164117.46+313607.0
16413+3136	STF2084		2014	836	141	1.3	2.95	5.40	G1IV	NOD	164117.46+313607.0
16413+3136	STF2084		2015	837	134	1.3	2.95	5.40	G1IV	NO	164117.46+313607.0
16413+3136	STF2084		2016	840	126	1.5	2.95	5.40	G1IV	NO	164117.16+313609.8
16413+3136	STF2084		2017	845	121	1.6	2.95	5.40	G1IV	NO	164117.16+313609.8
16413+3136	STF2084		2018	846	115	1.6	2.95	5.40	G1IV	NO	164117.16+313609.8
16413+3136	STF2084		2019	856	110	1.6	2.95	5.40	G1IV	NO	164117.16+313609.8

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Show	date	username	difficulty	separation	pa_estim	interest	notes
Show	17/08/26	oldscope	very difficult	separated			So, at 9:30, I turned my attention to another, more difficult double star that has always eluded me due to its tight separation and dissimilar magnitudes. Also easy to find, it is Zeta Herculis, “a modestly bright third magnitude (2.90) star orbited by a sixth magnitude (5.53) companion only a second of arc or so away.” It’s the ‘bottom right’ corner of the Hercules keystone, below M-13. How many times have you looked at M-13 with some big dob and ignored this great double? The current separation is 1.28 “, not much greater than the 1.01” theoretical limit for a 4-1/2 inch lens but not too hard if you have a lot more aperture and high quality optics. The faintness of the companion, which is easily lost in the diffraction ring of the primary, requires very steady seeing, and the star needs to be viewed while high up in the sky (less atmosphere). Very high power is required and if the Airy disk and diffraction ring are bobbing around, forget it. You won’t pick out the companion. But, finally, we were in luck! At about 47 deg. altitude, the moon setting, and the air very steady (9 out of 10 seeing), I noticed the faint little companion immediately at 343x and it was distinctly separated at 429 x. Just to be sure, I asked Nancy to confirm its position and without hesitation, she identified the exact location that I saw. This is a tough object for a five inch refractor, so I was very pleased with the performance of the 4-1/2 inch Brashear lens on this difficult double star tests. Not long after, I went to look at it again, but the seeing started to deteriorate and it became all but impossible to resolve. It was as if the double was thumbing its nose at me, saying “That’s all you get for now!”

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