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Article Contents

# Phase portraits of linear type centers of polynomial Hamiltonian systems with Hamiltonian function of degree 5 of the form $H = H_1(x)+H_2(y)$

• * Corresponding author: Claudio Vidal
• We study the phase portraits on the Poincaré disc for all the linear type centers of polynomial Hamiltonian systems of degree $5$ with Hamiltonian function $H(x,y) = H_1(x)+H_2(y)$, where $H_1(x) = \frac{1}{2} x^2+\frac{a_3}{3}x^3+ \frac{a_4}{4}x^4+ \frac{a_5}{5}x^5$ and $H_2(y) = \frac{1}{2} y^2+ \frac{b_3}{3}y^3+ \frac{b_4}{4}y^4+ \frac{b_5}{5}y^5$ as function of the six real parameters $a_3, a_4, a_5, b_3, b_4$ and $b_5$ with $a_5 b_5≠ 0$. We characterize the type and multiplicity of the roots of the polynomials $\hat{p}(y) = 1+b_3y + b_4 y^2+b_5y^3$ and $\hat{q}(x) = 1+a_3x+a_4x^2+a_5x^3$ and we prove that the finite equilibria are saddles, centers, cusps or the union of two hyperbolic sectors. For the infinite equilibria we found that there only exist two nodes on the Poincaré disc with opposite stability. We also characterize the separatrices of the equilibria and analyze the possible connections between them. As a complement we use the energy level to complete the global phase portrait.

Mathematics Subject Classification: Primary: 37C10; Secondary: 34C05.

 Citation:

• Figure 11.  Phase portraits for the systems associated to the Hamiltonian (5) when the roots of $\hat{p}(y)$ are $r\in \mathbb{R}$ and $a\pm ib$, and the roots of $\hat{q}(x)$ are $\rho$ and $\alpha\pm i\beta$. The separatrices are in bold. (a) $h_2<h_3$. (b) $h_2 = h_3$. (c) $h_2>h_3$

Figure 17.  Global phase portraits for the system (3) in the case Ⅰ-ⅱ for $r>0$ and $0<\sigma<\rho$. (a) $h_2 = h_4$ and $h_3 = h_5$. (b) $h_2 = h_4$ and $h_3<h_5$. (c) $h_2 = h_4$ and $h_5<h_3$. (d) $h_2<h_3<h_4<h_5$. (e) $h_3 = h_4$ and $h_2<h_5$. (f) $h_2<h_4<h_3<h_5$. (g) $h_3 = h_5$ and $h_2<h_4$. (h) $h_2<h_4<h_5<h_3$. (i) $h_4<h_2<h_3<h_5$. (j) $h_3 = h_5$ and $h_2>h_4$. (k) $h_4<h_2<h_5<h_3$

Figure 16.  Global phase portraits for the system (3) in the case Ⅰ-ⅱ for $r>0$ and $0<\rho<\sigma$. (a) $h_2<h_3 = h_4 = h_5$. (b) $h_2 = h_4<h_3 = h_5$. (c) $h_2 = h_4<h_5<h_3$. (d) $h_2<h_4 = h_5<h_3$. (e) $h_2<h_3<h_4<h_5$. (f) $h_2<h_3<h_4 = h_5$. (g) $h_2<h_3<h_5<h_4$. (h) $h_2<h_3 = h_4<h_5$. (i) $h_2<h_4<h_3<h_5$. (j) $h_2<h_4<h_3 = h_5$. (k) $h_2<h_4<h_5<h_3$. (l) $h_2<h_3 = h_5<h_4$. (m) $h_4<h_2<h_3<h_5$. (n) $h_4<h_2<h_3 = h_5$. (o) $h_4<h_2<h_5<h_3$. (p) $h_2<h_5<h_3<h_4$. (q) $h_2<h_5<h_3 = h_4$. (r) $h_2<h_5<h_4<h_3$

Figure 22.  Global Phase portraits for the system (3) in the case Ⅰ-ⅳ. Here consider $r>0$, $\rho<0<\sigma<\tau$. When four (a) or three saddle are in the energy level (a)-(i), $h_5 = h_8$ (j)-(o). (a) $h_2 = h_3 = h_5 = h_8$. (b) $h_8<h_2 = h_3 = h_5$. (c) $h_2 = h_3 = h_5<h_8$. (d) $h_5<h_2 = h_3 = h_8$. (e) $h_2 = h_3 = h_8<h_5$. (f) $h_3<h_2 = h_5 = h_8$. (g) $h_2 = h_5 = h_8<h_3$. (h) $h_2<h_3 = h_5 = h_8$. (i) $h_3 = h_5 = h_8<h_8$. (j) $h_5 = h_8<h_2<h_3$. (k) $h_2<h_5 = h_8<h_3$. (l) $h_2<h_3<h_5 = h_8$. (m) $h_5 = h_8<h_3<h_2$. (n) $h_3<h_5 = h_8<h_2$. (o) $h_3<h_2<h_5 = h_8$

Figure 23.  Global Phase portraits for the system (3) in case Ⅰ-ⅳ. Here consider $r>0$, $\rho<0<\sigma<\tau$ when two pairs of saddle are in the same energy level (a)-(f), $r>0$, $\rho<0<\sigma<\tau$ when $h_2 = h_3$ (g)-(l), and $r>0$, $\rho<0<\sigma<\tau$ when $h_2 = h_5$ (m)-(r). (a) $h_2 = h_3<h_5 = h_8$. (b) $h_2 = h_3>h_5 = h_8$. (c) $h_2 = h_5<h_3 = h_8$. (d) $h_2 = h_5>h_3 = h_8$. (e) $h_2 = h_8<h_3 = h_5$. (f) $h_2 = h_8>h_3 = h_5$. (g) $h_2 = h_3<h_5<h_8$. (h) $h_5<h_2 = h_3<h_8$. (i) $h_5<h_8<h_2 = h_3$. (j) $h_2 = h_3<h_8<h_5$. (k) $h_8<h_2 = h_3<h_5$. (l) $h_8<h_5<h_2 = h_3$. (m) $h_2 = h_5<h_3<h_8$. (n) $h_3<h_2 = h_5<h_8$. (o) $h_3<h_8<h_2 = h_5$. (p) $h_2 = h_5<h_8<h_3$. (q) $h_8<h_2 = h_5<h_3$. (r) $h_8<h_3<h_2 = h_5$

Figure 24.  Global Phase portraits for the system (3) in the case Ⅰ-ⅳ. Here consider $r>0$, $\rho<0<\sigma<\tau$ when $h_2 = h_8$ (a)-(f), $h_3 = h_5$ (g)-(l) and $h_3 = h_8$ (m)-(r). (a) $h_2 = h_8<h_3<h_5$. (b) $h_3<h_2 = h_8<h_5$. (c) $h_3<h_5<h_2 = h_8$. (d) $h_2 = h_8<h_5<h_3$. (e) $h_5<h_2 = h_8<h_3$. (f) $h_5<h_3<h_2 = h_8$. (g) $h_3 = h_5<h_2<h_8$. (h) $h_2<h_3 = h_5<h_8$. (i) $h_2<h_8<h_3 = h_5$. (j) $h_3 = h_5<h_8<h_2$. (k) $h_8<h_3 = h_5<h_2$. (l) $h_8<h_2<h_3 = h_5$. (m) $h_3 = h_8<h_2<h_5$. (n) $h_2<h_3 = h_8<h_5$. (o) $h_2<h_5<h_3 = h_8$. (p) $h_3 = h_8<h_5<h_2$. (q) $h_5<h_3 = h_8<h_2$. (r) $h_5<h_2<h_3 = h_8$

Figure 25.  Global Phase portraits for the system (3) in the case Ⅰ-ⅳ. Here consider $r>0$, $\rho<0<\sigma<\tau$ when $h_2<h_3<h_5$ (a)-(d), $h_2<h_5<h_3$ (e)-(h), $h_3<h_2<h_5$ (i)-(l), and $h_3<h_5<h_2$ (m)-(p). (a) $h_2<h_3<h_5<h_8$. (b) $h_2<h_3<h_8<h_5$. (c) $h_2<h_8<h_3<h_5$. (d) $h_8<h_3<h_3<h_5$. (e) $h_2<h_5<h_3<h_8$. (f) $h_2<h_5<h_8<h_3$. (g) $h_2<h_8<h_5<h_3$. (h) $h_8<h_2<h_5<h_3$. (i) $h_3<h_2<h_5<h_8$. (j) $h_3<h_2<h_8<h_5$. (k) $h_3<h_8<h_2<h_5$. (l) $h_8<h_3<h_2<h_5$. (m) $h_3<h_5<h_2<h_8$. (n) $h_3<h_5<h_8<h_2$. (o) $h_3<h_8<h_5<h_2$. (p) $h_8<h_3<h_5<h_2$

Figure 26.  Global phase portraits for the system (3) in the case Ⅰ-ⅳ. Here consider $r>0$, $\rho<0<\sigma<\tau$ when all the saddle are in different energy level and its satisfy $h_5<h_2<h_3$ (a)-(d), $h_5<h_3<h_2$ (e)-(h). (a) $h_5<h_2<h_3<h_8$. (b) $h_5<h_2<h_8<h_3$. (c) $h_5<h_8<h_2<h_3$. (d) $h_8<h_5<h_2<h_3$. (e) $h_5<h_3<h_2<h_8$. (f) $h_5<h_3<h_8<h_2$. (g) $h_5<h_8<h_3<h_2$. (h) $h_8<h_5<h_3<h_2$

Figure 29.  Local phase portraits at the equilibria of system (3) in the case Ⅱ-ⅱ. (a) $0<r<s$ and $0<\rho<\sigma$. (b) $r<0<s$ and $0<\rho<\sigma$. (c) $0<s<r$ and $\sigma<0<\rho$. (d) $r<0<s$ and $\sigma<0<\rho$. (e) $0<s<r$ and $0<\sigma<\rho$

Figure 30.  Local phase portraits at the equilibria of system (3) in the case Ⅱ-ⅳ. (a) if $0<r<s$. (b) if $0<s<r$

Figure 31.  Local phase portraits for system (3) in the case Ⅳ-ⅳ if $0<r<s<t$ and $0<\rho<\sigma<\tau$

Figure 2.  Local phase portrait at the origin of system (9). (a) $\tilde{w}>0$ and $\kappa>0$. (b) $\tilde{w}>0$ and $\kappa<0$. (c) $\tilde{w}<0$ and $\kappa>0$. (d) $\tilde{w}<0$ and $\kappa<0$

Figure 1.  Phase portrait in a neighborhood of the $w$-axis of system (10). (a) $\tilde{w}>0$ and $\kappa>0$. (b) $\tilde{w}>0$ and $\kappa<0$. (c) $\tilde{w}<0$ and $\kappa>0$. (d) $\tilde{w}<0$ and $\kappa<0$

Figure 3.  Blow-up at the origin of system (11). (a) Local phase portrait at the origin of the system (12). (b) Local phase portrait at the origin of the system (11)

Figure 4.  Assume $(\alpha_3-\tilde{y})/(\alpha_3 \tilde{y})>0$. (a) Local phase portrait in a neighbourhood at the $w$-axis of system (14). (b) Local phase portrait at the origin of system (13)

Figure 5.  Assume $(\alpha_3-\tilde{y})/(\alpha_3 \tilde{y})<0$. (a) Local phase portrait in a neighbourhood at the $w$-axis of system (14). (b) Local phase portrait at the origin of system (13)

Figure 6.  Blow-up of the origin of system (15). (a) Local phase portrait at in a neighborhood of the $w$-axis of system (16). (b) Local phase portrait at the origin of system (15)

Figure 7.  Local phase portrait of the equilibria of for the system (3) in the case Ⅰ-ⅰ

Figure 8.  Flow of system (3) over the straight lines $x = 0$, $x = \rho$, $y = 0$ and $y = r$ in the case Ⅰ-ⅰ

Figure 9.  The graphic of the auxiliary function $\nu_2(y)$

Figure 10.  The graphic of the auxiliary function $\mu_2(x)$. (a) $h_2<h_3$. (b) $h_2>h_3$

Figure 12.  Local phase portraits of the cusp $e_2 = (\sigma,0)$ and $e_5 = (\sigma,r)$ of system (20) according sign of $\sigma-\rho$ (assuming $\sigma,\rho>0$)

Figure 13.  Local phase portraits at the equilibria of system (3) in the case Ⅰ-ⅱ for $r>0$. (a) $0<\rho <\sigma$. (b) $0<\sigma <\rho$

Figure 14.  Flow of the vector field (3) over the straight lines $x = 0$, $x = \rho$, $x = \sigma$, $y = 0$ and $y = r$ in the case Ⅰ-ⅱ. (a) $0<\rho< \sigma$. (b) $0<\sigma<\rho$

Figure 15.  Phase portraits of separatrices in system (3) in the case Ⅰ-ⅱ with $r>0$. (a) $0<\rho< \sigma$. (b) $0<\sigma<\rho$

Figure 18.  Local phase portrait at the equilibrium $e_6$ of system (21) after translate it to the origin. (a) $(r-s)/(rs)>0$. (b) $(r-s)/(rs)<0$

Figure 19.  Local phase portraits at the equilibria of system 21 in the case Ⅱ-ⅲ with $\rho>0$. (a) if $0<r<s$. (b) if $0<s<r$

Figure 20.  Local phase portraits at the equilibria of system (3) in the case Ⅰ-ⅳ. (a) $r>0$ and $0<\rho<\sigma<\tau$. (b) $r>0$ and $\rho<0<\sigma<\tau$

Figure 21.  The vector field (22) over the straights lines $x = 0$, $x = \rho$, $x = \sigma$, $x = \sigma$, $y = 0$ and $y = r$ if $r>0$ and $\rho<0<\sigma<\tau$. (a) Vector field. (b) General analysis of the separatrices

Figure 27.  Local phase portraits for the nilpotent equilibria $e_3$ and $e_6$ in the case Ⅰ-ⅳ for $r>0$ shifted to the origin. (a) $e_3$ when $-(r-s)/(rs)>0$. (b) $e_3$ when $-(r-s)/(rs)<0$. (c) $e_6$ when $(r-s)/(rs)>0$. (d) $e_6$ when $(r-s)/(rs)<0$

Figure 28.  Local phase portrait at the equilibrium $e_9 = (\sigma,s)$ of system (24) after translation to the origin. (a) $(r-s)/(rs)>0$ and $(\rho-\sigma)/(\rho\sigma)>0$. (b) $(r-s)/(rs)>0$ and $(\rho-\sigma)/(\rho\sigma)<0$. (c) $(r-s)/(rs)<0$ and $(\rho-\sigma)/(\rho\sigma)>0$. (d) $(r-s)/(rs)<0$ and $(\rho-\sigma)/(\rho\sigma)<0$

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