Orbital Period Changes Research Articles

Investigation of the stability of the extreme low mass ratio contact binaries SX Crv and XX Sex, which are analysed photometrically

The photometric analyses of the extreme low mass ratio contact binaries SX Crv and XX Sex were conducted in detail. Light curves of SX Crv and XX Sex were retrieved from TESS, and light curve analyses were performed simultaneously with radial velocities. The mass ratios for SX Crv and XX Sex were calculated as 0.077(1) and 0.099(2). The masses of the primary components account for about 90% of the total masses of the systems and were determined to be 1.256(48) M⊙ and 1.337(37) M⊙ for SX Crv and XX Sex, respectively. It has been observed that the orbital periods of both systems have increased. The orbital period change rate of SX Crv has been calculated to be 0.39 s per century, while that of XX Sex has been calculated to be 2.68 s per century. The orbital angular momentum (Jo) determined for both systems is more than 3 times the spin angular momentum (Js), and it can be said that the SX Crv and XX Sex systems are stable. The calculated instability separation (ains.) and instability mass ratio (qins.) values for both systems are smaller than those obtained in the analyses, which supports the stability. The estimated ages of the systems are 7.4 Gyr for SX Crv and 3.9 Gyr for XX Sex. logMtot – logJ and logTeff – logL diagrams were also interpreted to better understand the evolution of the extreme low mass ratio contact binaries.

Orbital period change of SW Sex star TT Tri

Abstract SW Sex-type stars are the dominate population of cataclysmic variables (CVs) just above the period gap and are vital for understanding of CV evolution. We have monitored TT Tri for nearly 15 yr, and more observations yield a more reliable estimation for its orbital period variation. In this work, we present a detailed analysis about its orbital period variation. TT Tri experiences a rapid period decay with a decay rate of −5.67 × 10−11 s/s plus a period oscillation at about 9.6 years. The oscillation could be caused by the magnetic activities of the low-mass star or/and a circumbinary body, while the rapid period decrease can not be accounted for by the magnetic braking or even including an intensive disk wind. We find that mass overflow though the L3 point can take the angular momentum away effectively and that this mass overflow could account for the rapid period decay observed in TT Tri. We propose that this kind of angular momentum loss may play a crucial role in CV evolution, and further research is in progress.

Discoveries and timing of pulsars in M62

ABSTRACT Using MeerKAT, we have discovered three new millisecond pulsars (MSPs) in the bulge globular cluster M62: M62H, M62I, and M62J. All three are in binary systems, which means all ten known pulsars in the cluster are in binaries. M62H has a planetary-mass companion with a median mass Mc, med ∼ 3 MJ and a mean density of ρ ∼ 11 g cm−3. M62I has an orbital period of 0.51 d and a Mc, med ∼ 0.15 M⊙. Neither of these low-mass systems exhibit eclipses. M62J has only been detected in the two Ultra High Frequency band (816 MHz) observations with a flux density S816 = 0.08 mJy. The non-detection in the L-band (1284 MHz) indicates it has a relatively steep spectrum (β < −3.1). We also present 23-yr-long timing solutions obtained using data from the Parkes ‘Murriyang’, Effelsberg, and MeerKAT telescopes for the six previously known pulsars. For all these pulsars, we measured the second spin-period derivatives and the rate of change of orbital period caused by the gravitational field of the cluster, and their proper motions. From these measurements, we conclude that the pulsars’ maximum accelerations are consistent with the maximum cluster acceleration assuming a core-collapsed mass distribution. Studies of the eclipses of the redback M62B and the black widow M62E at four and two different frequency bands, respectively, reveal a frequency dependence with longer and asymmetric eclipses at lower frequencies. The presence of only binary MSPs in this cluster challenges models which suggest that the MSP population of core-collapsed clusters should be dominated by isolated MSPs.

Spectroscopic searches for evolutionary orbital period changes in WR+OB binaries: The case of WR 127 (Hen 3-1772)

Aims. We aim to determine the secular evolution of the orbital period of the short-period binary system WR 127 (WN3b+O9.5V, P ≈ 9.555d). Methods. We performed new low-resolution spectroscopic observations of WR 127 with the 2.5 m CMO SAI telescope to construct the radial velocity curves of the components. Our results suggest component masses of MWRsin3(i) = 11.8 ± 1.4 M⊙ and MOsin3(i) = 17.2 ± 1.4 M⊙. By comparing these values with archival radial velocity curves we were able to create an (O − C) plot with an accuracy sufficient to search for the orbital period change in WR 127. Results. We report the reliable detection of a secular increase in the orbital period of WR 127 at a rate of Ṗ = 0.83 ± 0.14 s yr−1, which corresponds to a dynamical mass-loss rate from the Wolf-Rayet (WR) star of ĖWR = (2.6 ± 0.5) × 10−5 M⊙ yr−1. Conclusions. The mass-loss rate from WR stars in three Wolf-Rayet+OB binaries (WR 127, CX Cep, and V444 Cyg) as inferred from spectroscopic and photometric measurements suggests a preliminary empirical correlation between a WR star’s mass and its dynamical mass-loss rate of ṀWR ∼ MWR1.8. This relation is important for the understanding of the evolution of massive close binaries that include WR stars as such an evolution is a precursor of gravitational-wave binary merging events with neutron stars and black holes.

Periodic Variation Studies of the Two Short Period W UMa-type Eclipsing Binaries: LX Lyn and V0853 Aur

In this paper, new light curves (LCs) of contact eclipsing binary (CEB) systems LX Lyn and V0853 Aur are presented and analyzed by using the 2015 version of the Wilson–Devinney (W-D) code. In order to explain their asymmetric LCs, cool starspots on the components were employed. It is suggested that their fill-out degrees are f = 12.0% (LX Lyn) and f = 26.3% (V0853 Aur). At the same time, we found that LX Lyn is a W-type eclipsing binary (EB) with an orbital inclination of i = 84.°88 and a mass ratio of q = 2.31. V0853 Aur is also a W-type CEB with a mass ratio of q = 2.77 and an orbital inclination of i = 79.°26. Based on all available times of light minimum, their orbital period changes are studied by using the O − C method. The O − C diagram of LX Lyn reveals a cyclic oscillation with a period of about 14.84 yr and an amplitude of 0.0019 days, which can be explained by the light-travel time effect (LTTE) due to the presence of a third body with a minimum mass of 0.06M ⊙. For V0853 Aur, it is discovered that the O − C diagram of the system also shows a cyclic oscillation with a period of 9.64 yr and an amplitude of 0.03365 days. The cyclic oscillation of V0853 Aur can be attributed to the LTTE by means of a third body with a mass no less than 3.77M ⊙. The third body may play an important role in the formation and evolution of these systems.

Investigation of Orbital Period Changes in Nine Contact Binaries

We present the results for orbital period analysis of nine contact binaries (CBs). The photometric data analysed in this work is collected using ARIES 1-m and 1.3-m telescopes as well as many ground and space-based photometric surveys. The precise orbital periods of the binary systems are studied using the long time-baseline of data acquired over the last 12-15 years. The changes in the times of minimum brightness are calculated using (O-C) diagram. Out of these nine CBs, four systems show no change in the orbital period with time while the remaining five systems show non-linear (O-C) variations with time. We derive mass transfer rates for these five CBs which suggests mass is being transferred from secondary to primary components in three systems while it is from primary to secondary components in the other two systems.

Orbital Period Changes of the Eclipsing Binaries RW Cap, BG Peg, and CU Peg

Orbital Period Changes of the Eclipsing Binaries RW Cap, BG Peg, and CU Peg

Update on WASP-19

Tidal interaction between a star and a close-in massive exoplanet causes the planetary orbit to shrink and eventually leads to tidal disruption. Understanding orbital decay in exoplanetary systems is crucial for advancing our knowledge of planetary formation and evolution. Moreover, it sheds light on the broader question of the long-term stability of planetary orbits and the intricate interplay of gravitational forces within stellar systems. Analyzing Transiting Exoplanet Survey Satellite (TESS) data for the ultra-short period gas giant WASP-19, we aim to measure orbital period variations and constrain the stellar tidal quality parameter. For this, we fitted the TESS observations together with two WASP-19 transits observed using the Las Cumbres Observatory Global Telescope (LCOGT) and searched for orbital decay in combination with previously published transit times. As a result, we find a deviation from the constant orbital period at the 7σ level. The orbital period changes at a rate of P˙=−3.7±0.5msyear−1, which translates into a tidal quality factor of Q★′=(7±1)×105. We additionally modeled WASP-19 b’s phase curve using the new TESS photometry and obtained updated values for the planet’s eclipse depth, dayside temperature, and geometric albedo. We estimate an eclipse depth of 520±60 ppm, which is slightly higher than previous estimates and corresponds to a dayside brightness temperature of 2400±60 K and geometric albedo of 0.20±0.04.

Optical Monitoring of the Didymos–Dimorphos Asteroid System with the Danish Telescope around the DART Mission Impact

The NASA’s Double-Asteroid Redirection Test (DART) was a unique planetary defence and technology test mission, the first of its kind. The main spacecraft of the DART mission impacted the target asteroid Dimorphos, a small moon orbiting the asteroid Didymos (65803), on 2022 September 26. The impact brought up a mass of ejecta which, together with the direct momentum transfer from the collision, caused an orbital period change of 33 ± 1 minutes, as measured by ground-based observations. We report here the outcome of the optical monitoring campaign of the Didymos system from the Danish 1.54 m telescope at La Silla around the time of impact. The observations contributed to the determination of the changes in the orbital parameters of the Didymos–Dimorphos system, as reported by Thomas et al., but in this paper we focus on the ejecta produced by the DART impact. We present photometric measurements from which we remove the contribution from the Didymos–Dimorphos system using an H–G photometric model. Using two photometric apertures we determine the fading rate of the ejecta to be 0.115 ± 0.003 mag day−1 (in a 2″ aperture) and 0.086 ± 0.003 mag day−1 (5″) over the first week postimpact. After about 8 days postimpact we note the fading slows down to 0.057 ± 0.003 mag day−1 (2″ aperture) and 0.068 ± 0.002 mag day−1 (5″). We include deep-stacked images of the system to illustrate the ejecta evolution during the first 18 days, noting the emergence of dust tails formed from ejecta pushed in the antisolar direction, and measuring the extent of the particles ejected Sunward to be at least 4000 km.

Spectroscopic searches for evolutionary orbital period changes in WR+OB binaries: the case of V444 Cyg

ABSTRACT We present the results of new photometric and spectroscopic observations of the WN5+O6 binary V444 Cyg and a detailed analysis of extant spectroscopy and photometry. Using elements of the spectroscopic orbit and assuming e ≈ 0, i ≈ 78° we determined the masses and orbit sizes of the components of V444 Cyg as MO6 ≈ 26.4 M⊙, MWN5 ≈ 10.7 M⊙, aO6 ≈ 10.6 R⊙, aWN5 ≈ 26.1 R⊙. Based on new and archival light curves and using the Hertzsprung method, we improved the photometric estimate of the secular increase rate of the orbital period in V444 Cyg, obtaining $\dot{P}_{\mathrm{ph}} = 0.119\pm 0.003$ s yr−1. From a comparison of the new and archival radial velocity curves of V444 Cyg, we independently derived the secular orbital period change rate as $\dot{P}_{\mathrm{sp}} = 0.147\pm 0.032$ s yr−1, in agreement with the photometric $\dot{P}_{\mathrm{ph}}$. The obtained secular increase rate of the binary orbital period $\dot{P}$ and the mean radii of the components enabled us to estimate the stellar wind mass-loss rate from the WR star as $\dot{M}_{\mathrm{WN5}} = -(6.0\pm 0.4)\times 10^{-6}~{\rm M}_{\odot }\mbox{ yr}^{-1}$.

Orbital period changes for 14 novae and the critical failures of the predictions of standard theories, the Hibernation Model, and the Magnetic Braking Model

ABSTRACT The evolution of novae and cataclysmic variables (CVs) is driven by changes in the binary orbital periods. In a direct and critical test for various evolution models and their physical mechanisms, I measure the sudden changes in the period (ΔP) across 14 nova eruptions, and I measure the steady period change during quiescence (Ṗ) for 20 inter-eruption intervals. The standard theory for ΔP is dominated by the mechanism of mass loss, and this fails completely for the five novae with negative values, and it fails to permit the ΔP for U Sco eruptions to change by one order of magnitude eruption to eruption. The Hibernation Model of evolution is refuted because all the ΔP measures are orders of magnitude too small to cause any significant drop in accretion luminosity, and indeed, near half of the nova have negative ΔP as the opposite of the required mechanism for any hibernation state. As for the Magnetic Braking Model, this fails by many orders of magnitude in its predictions of the required Ṗ for 9 out of 13 novae. The observed Ṗ values scatter, both positively and negatively, over a range of ±10−9, while the predicted values are from −10−13 to −10−11. This huge scatter is not possible with standard theory, and there must be some currently unknown mechanism to be added in, with this new mechanism 100–10 000× larger in effect than the current theory allows. In all, these failed predictions demonstrate that nova systems must have unknown physical mechanisms for both ΔP and Ṗ that dominate over all other effects.

First photometric analysis of the two EW binaries ZTF J214226.88+435827.1 and KAO-EGYPT J214216.38+440015.1

The EW-type eclipsing binaries are strongly interacting systems known to have often both component stars filling their crucial Roche lobes and having a common envelope. We present new BVRI light curves of the eclipsing binaries ZTF J214226.88+435,827.1 (ZTF21+43) and KAO-EGYPT J214216.38+440,015.1 (KAO21+44) based on CCD observations acquired with the 1.88-m Kottamia Astronomical Observatory (KAO) at Newtonian and Cassegrain telescope focus. The modeling results show that these two systems are to be W UMa contact binaries belonging to EW subtypes. All the light curves show the inverse O'Connell effect. We computed new ephemeris for each system using our times of minima and that available in the literature. Using our new times of minima and epochs for both systems from all available observations, the orbital period changes of these structures are studied for our systems. Using the PHOEBE package, a preliminary determination of the two systems' photometric orbital and physical parameters has been present. The positions of the systems were also depicted on the Hertzsprung-Russell (H-R), M-L, and Teff-L diagrams to test their evolutionary status.

The first photometric, period variation, and flare activity studies of TIC 24233294: Reviewing with the latest results of well-studied late-type active binaries

In the current study, we present the first photometric, period variation, and flaring activity investigations of TIC 24233294. Additionally, we also review and report the flaring activity of five well-studied eclipsing binaries BX Tri, V405 And, GJ 3236, Thor 42, and GU Boo. Using the Transiting Exoplanet Survey Satellite (TESS) data, continuous variations in the light curves of binaries TIC 24233294, and BX Tri are analysed and presented. The primary and secondary components of all the six binaries in the study are M-type dwarfs. All these binaries are observed to be in detached/semi-detached configuration. Photometric analysis on TIC 24233294 and BX Tri was carried out using the Wilson–Devinney program. The long-term orbital period changes are analyzed and presented, on the basis of photometric solutions and the evolutionary status of the binary systems in the study. Flares are observed to be common in stars with outer convection zones. We identified flares on all binaries in the study and calculated their characteristic parameters like amplitudes, frequency, duration, and energies. Many superflares and few hyperflares were identified in the list of flares detected within the energy range of 1033-1037 erg. The flare events in the binaries could be related to the strong tidal interactions between the components of the binaries and fully/deeper convective interiors.

First Detailed Photometric Investigation on the Nature of Contact Binary System AA Cet

The TESS light curve (LC) of the marginal contact binary AA Cet was analyzed simultaneously with the radial velocity and the orbital period (OP) change of the system was investigated. The physical parameters of the system were obtained by analyzing the LC of AA Cet with the Wilson-Devinney method, and the absolute parameters of the components were calculated using the results obtained. For the components of AA Cet, the masses and radii were calculated as M 1 = 1.39 ± 0.04 M ⊙, M 2 = 0.48 ± 0.02 M ⊙ and R 1 = 1.64 ± 0.03 R ⊙, R 2 = 1.01 ± 0.04 R ⊙, respectively. AA Cet is a marginal contact binary with a temperature difference of 1305 K between its components. A total of 14 eclipse times were obtained from the TESS data and used in the OP analysis together with those collected from the literature. It has been observed that the change in the OP of AA Cet is in the form of a decreasing parabola. Conservative mass transfer between the components has been interpreted as the reason for this change. The OP decrease amount of AA Cet was obtained as dP/dt = 0.0062 ± 0.0006 s yr−1, and the reason for this decrease was attributed to a 3.3(9) × 10−8 M ⊙ mass transfer per year from the more massive component to the less massive one. The age of AA Cet has been estimated as 7 Gyr, as the age of contact systems helps us to understand their evolution.

Spectroscopic searches for evolutionary orbital period changes in WR + OB binaries: the case of CQ Cep and CX Cep

ABSTRACT We present the results of spectroscopic observations of two eclipsing WR + OB-type systems – CQ Cep and CX Cep – performed in 2020–2023 with a low-resolution slit spectrograph TDS (λλ = 3660–7410 Å, R = 1300–2500) on 2.5-m telescope of the SAI MSU Caucasian Mountain Observatory. For CQ Cep, the radial velocity curves of a WN6 star are constructed, the problem of visibility of spectroscopic traces of an OB star is discussed, and the components’ mass ratio q ∼ 0.6 is estimated. For CX Cep, the radial velocity curves are constructed for both the WN5 and O5 components enabling their masses and circular orbit elements to be refined. The comparison of the radial velocity curves of these systems obtained in different epochs allowed us to derive the orbital period change rate $\dot{P}$ by the spectroscopic method, which is found to be in good agreement with estimates obtained by comparing the moments of primary eclipse minima: $\dot{P} = -0.0151\pm 0.0013$ s yr−1 for CQ Cep and $\dot{P} = 0.054\pm 0.009$ s yr−1 for CX Cep. The prospects of applicability of the spectroscopic dynamical method for studying the orbital evolution of Galactic WR + OB binaries and related objects are considered. We also discuss the effect of finite sizes of stars with stellar wind mass-loss in close binary systems on their orbital evolution.

OT UMa and 2MASS J09251388+6424488: Two active contact eclipsing binary systems

In this paper, new photometric light curves (LCs) of OT UMa and 2MASS J09251388+6424488 (=NSVS 2497620, hereafter NSVS 2497) in BVRcIc-bands are presented and analyzed by using the 2015 version of the Wilson–Devinney (W–D) code. We found that both of them are active contact eclipsing binaries (CEBs) . At the same time, we estimated masses and radii of OT UMa and NSVS 2497 by using our photometric parameters. Then, we also studied the orbital period changes of them by using the O−C method via collecting all available times of light minimum for the first time, and new linear ephemerides are obtained. Besides, the formation and evolution of these two targets are discussed, and we thought that OT UMa could be undergoing thermal relaxation oscillations.

Orbital period change of Dimorphos due to the DART kinetic impact

The Double Asteroid Redirection Test (DART) spacecraft successfully performed the first test of a kinetic impactor for asteroid deflection by impacting Dimorphos, the secondary of near-Earth binary asteroid (65803) Didymos, and changing the orbital period of Dimorphos. A change in orbital period of approximately 7 min was expected if the incident momentum from the DART spacecraft was directly transferred to the asteroid target in a perfectly inelastic collision1, but studies of the probable impact conditions and asteroid properties indicated that a considerable momentum enhancement (β) was possible2,3. In the years before impact, we used lightcurve observations to accurately determine the pre-impact orbit parameters of Dimorphos with respect to Didymos4–6. Here we report the change in the orbital period of Dimorphos as a result of the DART kinetic impact to be −33.0 ± 1.0 (3σ) min. Using new Earth-based lightcurve and radar observations, two independent approaches determined identical values for the change in the orbital period. This large orbit period change suggests that ejecta contributed a substantial amount of momentum to the asteroid beyond what the DART spacecraft carried.

Repeating periodic eruptions of the supernova impostor SN 2000ch

ABSTRACT We analyse photometric observations of the supernova (SN) impostor SN 2000ch in NGC 3432 covering the time since its discovery. This source was previously observed to have four outbursts in 2000–2010. Observations now reveal at least three additional outbursts in 2004–2007, and 16 outbursts in 2010–2022. Outburst light curves are irregular and multipeaked, exhibiting a wide variety of peak magnitude, duration, and shape. The outbursts after 2008 repeat with a period of 200.7 ± 2 d, while the outburst in 2000 seems to match with a shorter period. The next outburst should occur around January/February 2023. We propose that these periodic eruptions arise from violent interaction around times of periastron in an eccentric binary system, similar to the periastron encounters of η Carinae leading up to its Great Eruption, and resembling the erratic pre-SN eruptions of SN 2009ip. We attribute the irregularity of the eruptions to the interplay between the orbit and the variability of the luminous blue variable (LBV) primary star, wherein each successive periastron pass may have a different intensity or duration due to the changing radius and mass-loss rate of the LBV-like primary. Such outbursts may occasionally be weak or undetectable if the LBV is relatively quiescent at periastron but can be much more extreme when the LBV is active. The observed change in orbital period may be a consequence of mass lost in outbursts. Given the similarity to the progenitor of SN 2009ip, SN 2000ch deserves continued attention in the event it is headed for a stellar merger or an SN-like explosion.

Physical Properties of Three Eclipsing Binaries of V Crt, WY Cnc and CG Cyg with Radio Radiation

Radio radiation has been detected across the Hertzsprung Russell diagram. We selected three objects with radio radiation (a semi-detached eclipsing binary V Crt, and two detached binaries WY Cnc and CG Cyg) that show magnetic activity. We made new photometric observations using a SARA 60 cm and NAOC 85 cm optical telescopes. Then, we obtained their orbital and starspot parameters by analyzing our light curves and published radial velocities using the updated Wilson-Devinney program. We revised the ephemeris information for V Crt and WY Cnc by analyzing the orbital minimum times. The orbital periods increased by 2.8 (±2.1) ×10−9 d yr−1 for V Crt, which maybe caused by mass transfer. The orbital periods decreased by −8.641 (±0.004) ×10−8 d yr−1 for WY Cnc. Orbital period change for CG Cyg was also found and we used a third-body of M3 of 0.14 M⊙ and a period of approximately 59.20 (0.36) yr to explain that. We also analysed the possible second period oscillation of CG Cyg with a cycle about 18.31 (0.06) yr. The long period changes of WY Cnc and CG Cyg might be caused by magnetic activity or stellar wind, rather than mass transfer.

New photometric solutions of contact binaries HX UMa and FP Boo

By using different databases (TESS, SuperWASP, KWS and ASAS-SN), light curve analyzes of HX UMa and FP Boo systems were performed, and the changes in the orbital period of the systems were also examined. The light curve analyzes of the systems were conducted simultaneously with the radial velocities using the Wilson and Devinney (WD) code. As a result of the analyzes, the masses and radii of the components were determined as M1=1.29±0.02 M⊙, M2=0.38±0.02 M⊙, R1=1.21±0.02 R⊙, R2=0.78±0.02 R⊙ for HX UMa and M1=1.68±0.05 M⊙, M2=0.16±0.01 M⊙, R1=2.28±0.02 R⊙, R2=0.82±0.02 R⊙ for FP Boo, respectively. The distances of HX UMa and FP Boo were calculated as 123±11 pc and 350±23 pc, respectively, and were almost the same as Gaia DR3 values. When the orbital period changes were examined, it was determined that the orbital period of the HX UMa system increased, while the FP Boo decreased. The orbital period increase rate of HX UMa was calculated as dP/dt=9×10−8 d yr−1 and the period decrease rate of FP Boo was calculated as dP/dt=1.7×10−6 d yr−1. Mass transfer between components has been suggested as the reason for the period changes. Along with the orbital period changes, a cyclical change was observed in both systems. Magnetic activity or a possible third component can cause cyclical variation. The periods of these cyclical changes are determined as 24±4 yr and 20±1 yr, respectively.