arXiv subjects

Pasi Hakala

Publications and source records attributed to Pasi Hakala.

At least 19 recordsLinked to original sources

arXiv2026

CoBiToM project. III. Physical characterisation of the potential merger candidates AL Lep, ASAS J082243+1927.0, and ZZ PsA

Contact binaries (CBs) are key systems for investigating the late evolutionary stages that may lead to stellar coalescence. Systems with an extremely low mass ratio and high fill-out factor are of particular interest as potential merger candidates and possible progenitors of luminous red novae. A combined photometric and spectroscopic study of the CB systems AL Lep, ASAS J082243+1927.0, and ZZ PsA is presented. The aim is to derive self-consistent orbital and physical parameters, assess their evolutionary state, and examine whether they have reached the terminal and unstable phase of their evolution. High-resolution VLT/UVES spectra were analysed to derive radial velocity values, spectroscopic mass ratio, and metallicity. The results were combined with multi-band light-curve modelling within a Monte Carlo framework to determine the system geometries and absolute parameters. Orbital period variations were investigated through O-C analysis, while the evolutionary status of the systems was assessed using the Darwin instability criterion, critical mass ratio estimates, fill-out factor, and orbital period variation. Mass ratio values of q = 0.1332, 0.1041, and 0.0789 were derived for AL Lep, ASAS J082243+1927.0, and ZZ PsA, respectively. The corresponding primary mass values are M1 = 1.656 +/- 0.081 Msun, 1.275 +/- 0.078 Msun, and 1.795 +/- 0.111 Msun. The locations of their components show significant deviations from single-star ZAMS and TAMS reference curves, indicating strong binary interaction and energy redistribution through the common envelope. The spin-to-orbital angular momentum ratio for AL Lep and ASAS J082243+1927.0 remains below the standard Darwin instability threshold, while ZZ PsA lies close to the instability regime and may be consistent with an unstable configuration within the derived uncertainties.

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arXiv2026

Circular polarimetry of suspect wind-accreting pre-polars II

The origin of white dwarf magnetic fields is an open question. Furthermore, such fields play a vital role in the evolution of interacting binary stars. Here we present a study of white dwarf fields in so called pre-polars (or low accretion rate polars, LARPs , i.e. magnetic cataclysmic variables, where the mass losing secondary star is not in Roche lobe contact, but the systems experience accretion via stellar wind. Such systems play a crucial role in understanding the magnetic braking and the angular momentum evolution of close binaries. We aim to identify a set of wind-accreting pre-polars amongst our sample of nine candidate systems. We also attempt to measure the white dwarf magnetic fields and study the accretion geometry associated with wind-accreting pre-polars. We have obtained optical circular imaging photopolarimetry and circular spectropolarimetry of the targets. These are used to model the cyclotron emission and to estimate the white dwarf magnetic field strengths. We find that at least in four out of our nine candidate systems, we can confirm the magnetic nature of the white dwarf. Out of these, One system, ZTF J1737+4013, appears to be an eclipsing polar. Furthermore, ZTF J2220+0721 and ZTF J2353+4153 appear to be very strong candidates for wind-accreting pre-polars (or LARPs), with the fourth, ZTF J0056+4926, showing strong variable $H_α$ emission, atypical of pre-polars. However, the emission could be related to the strong activity of the donor star, dominating the optical spectrum. One system, ZTF J0504+2145, is likely a novalike CV. The exact nature of the other systems remains unclear.

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arXiv2026

The puzzling story of flare inactive ultra fast rotating M dwarfs -- III. Investigating X-ray Activity

According to activity-rotation relations, rapid rotators are expected to show high levels of magnetic activity. However, recent studies with TESS have found Ultra Fast Rotating (UFR) M dwarfs with periods $<1$ d displaying low levels of flaring activity. There have been efforts to explore their magnetic field strengths through spectropolarimetric measurements and to assess the potential for binarity. However, neither could fully explain the lack of observed flaring activity despite their rapid rotation. Another avenue for investigation is to measure their coronal emission for signs of supersaturation: an underluminosity in X-rays observed for some rapidly rotating FGK stars. Therefore, in this study, we utilise X-ray observations from Swift and XMM-Newton of ten M dwarf UFRs with P$_{\rm{rot}}$<1 d to determine their X-ray luminosities. Overall, we do not find evidence for supersaturation amongst our UFR M dwarf stars, instead determining them to be at the saturated level, or perhaps even enhanced. Therefore, supersaturation seems not to be the main driver behind the reduced level of flaring activity observed in these stars, and the mystery behind the magnetic activity of UFR low-mass stars remains. Additionally, we provide an updated analysis on the long term variability within our sample using TESS light curves taken during Cycles 5 and 7. We identify 352 optical flares from our sample with energies between $1.2\times10^{31}$ and $8.7\times10^{34}$ erg. We determine flare rates for each TESS cycle, compare them, identifying variations across a 7 year timespan and attribute this to potential activity cycles.

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arXiv2025

V Sge: Supersoft Source or Exotic Hot Binary? I. An X-Shooter campaign in the high state

V Sge is a peculiar, highly luminous long-period (12.34h) binary star that can display a super-soft X-ray emitting component when in the faint phase of its V~ 10-13mag variability range. Apparently undergoing Eddington-limited accretion from its more massive secondary, it is in a very rare, short-lived evolutionary phase towards the double degenerate channel. Its complex and highly variable optical emission features, from Balmer and Heii to high-ionisation lines, including strong fluorescence features, have been challenging to interpret, especially given the absence of any absorption lines associated with photospheric features from either stellar component. With the detailed properties of V Sge, especially the donor, still controversial, we undertook a VLT/X-Shooter campaign over three months in 2023, obtaining high S/N, high resolution spectra that revealed multiple components in both high- and low-ionisation lines. This allows us to track V Sge's principal emitting regions via Doppler tomography, obtaining new insights into high accretion-rate dynamics. In particular, we identify a stationary, double-peaked emission core which we interpret as a circumbinary ring, analogous to SS433. This enables us to derive limits on the system masses. Furthermore, we find very broad emission-line wings whose mean velocity can vary over hundreds of kilometres per second on timescales of decades, yet ``flip'' between states in <1 week. We show that the super-soft X-ray source interpretation is able to account for these and other observational attributes significantly better than the hot binary model, concluding that V Sge could be one of the brightest known Galactic super-soft sources.

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arXiv2025

ASASSN-14dx: A cataclysmic variable harbouring a massive pulsating white dwarf

We present the results of our study of ASASSN-14dx, a previously known but poorly characterised cataclysmic variable (CV). The source was observed as part of an ongoing high-time-resolution photometric survey of CVs, which revealed that, in addition to the known 82.8min orbital period, it also exhibits other transient periods, the strongest of which around 4 and 14 min. Here, we report our findings resulting from a multifaceted follow-up programme consisting of optical spectroscopy, spectropolarimetry, imaging polarimetry, and multicolour fast photometry. We find that the source displays complex optical variability, which is best explained by the presence of a massive white dwarf exhibiting non-radial pulsations. An intermediate polar-like scenario involving a spinning magnetic white dwarf can be ruled out based on the detected changes in the observed periods. Based on our optical spectroscopy, we can constrain the mass and effective temperature of the white dwarf to be ~1.1 Msol and 16 100 K, respectively. The overall intrinsic flux level of the source is unusually high, suggesting that there remains significant residual emission from the accretion disc and/or the white dwarf even ten years after the 2014 outburst. Finally, we cannot detect any spectroscopic signatures from the donor star, making ASASSN-14dx a possible period bouncer system evolving towards a longer orbital period.

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arXiv2025

Discovery of two new polars evolved past the period bounce

We report the discovery of two new magnetic cataclysmic variables with brown dwarf companions and long orbital periods ($P_{\rm orb}=95\pm1$ and $104\pm2$ min). This discovery increases the sample of candidate magnetic period bouncers with confirmed sub-stellar donors from four to six. We also find their X-ray luminosity from archival XMM-Newton observations to be in the range $L_{\rm X}\approx10^{28}$$-$$10^{29} \mathrm{erg\,s^{-1}}$ in the 0.25$-$10 keV band. This low luminosity is comparable with the other candidates, and at least an order of magnitude lower than the X-ray luminosities typically measured in cataclysmic variables. The X-ray fluxes imply mass transfer rates that are much lower than predicted by evolutionary models, even if some of the discrepancy is due to the accretion energy being emitted in other bands, such as via cyclotron emission at infrared wavelengths. Although it is possible that some or all of these systems formed directly as binaries containing a brown dwarf, it is likely that the donor used to be a low-mass star and that the systems followed the evolutionary track for cataclysmic variables, evolving past the period bounce. The donor in long period systems is expected to be a low-mass, cold brown dwarf. This hypothesis is supported by near-infrared photometric observations that constrain the donors in the two systems to be brown dwarfs cooler than $\approx$1100 K (spectral types T5 or later), most likely losing mass via Roche Lobe overflow or winds. The serendipitous discovery of two magnetic period bouncers in the small footprint of the XMM-Newton source catalog implies a large space density of these type of systems, possibly compatible with the prediction of 40$-$70 per cent of magnetic cataclysmic variables to be period bouncers.

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arXiv2025

A Link Between White Dwarf Pulsars and Polars: Multiwavelength Observations of the 9.36-Minute Period Variable Gaia22ayj

White dwarfs (WDs) are the most abundant compact objects, and recent surveys have suggested that over a third of WDs in accreting binaries host a strong (B $\gtrsim$ 1 MG) magnetic field. However, the origin and evolution of WD magnetism remain under debate. Two WD pulsars, AR Sco and J191213.72-441045.1 (J1912), have been found, which are non-accreting binaries hosting rapidly spinning (1.97-min and 5.30-min, respectively) magnetic WDs. The WD in AR Sco is slowing down on a $P/\dot{P}\approx 5.6\times 10^6$ yr timescale. It is believed they will eventually become polars, accreting systems in which a magnetic WD (B $\approx 10-240$ MG) accretes from a Roche lobe-filling donor spinning in sync with the orbit ($\gtrsim 78$ min). Here, we present multiwavelength data and analysis of Gaia22ayj, which outbursted in March 2022. We find that Gaia22ayj is a magnetic accreting WD that is rapidly spinning down ($P/\dot{P} = 6.1^{+0.3}_{-0.2}\times 10^6$ yr) like WD pulsars, but shows clear evidence of accretion, like polars. Strong linear polarization (40%) is detected in Gaia22ayj; such high levels have only been seen in the WD pulsar AR Sco and demonstrate the WD is magnetic. High speed photometry reveals a 9.36-min period accompanying a high amplitude ($\sim 2$ mag) modulation. We associate this with a WD spin or spin-orbit beat period, not an orbital period as was previously suggested. Fast (60-s) optical spectroscopy reveals a broad ``hump'', reminiscent of cyclotron emission in polars, between 4000-8000 Angstrom. We find an X-ray luminosity of $L_X = 2.7_{-0.8}^{+6.2}\times10^{32} \textrm{ erg s}^{-1}$ in the 0.3-8 keV energy range, while two VLA radio campaigns resulted in a non-detection with a $F_r < 15.8μ\textrm{Jy}$ 3$ σ$ upper limit. The shared properties of both WD pulsars and polars suggest that Gaia22ayj is a missing link between the two classes of magnetic WD binaries.

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arXiv2024

Characterising high and low accretion states in VY Scl CVs using ZTF and TESS data

VY Scl binaries are a sub-class of cataclysmic variable (CV) which show extended low states, but do not show outbursts which are seen in other classes of CV. To better determine how often these systems spend in low states and to resolve the state transitions we have analysed ZTF data on eight systems and TESS data on six systems. Half of the sample spent most of the time in a high state; three show a broad range and one spends roughly half the time transitioning between high and low states. Using the ZTF data we explore the colour variation as a function of brightness. In KR Aur, we identify a series of repeating outburst events whose brightness appears to increase over time. Using TESS data we searched for periods other than the orbital. In LN UMa we find evidence for a peak whose period varies between 3-6 d. We outline the current models which aim to explain the observed properties of VY Scl systems which includes disc irradiation and a white dwarf having a significant magnetic field.

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arXiv2024

The mass of the white dwarf in YY Dra (=DO Dra): Dynamical measurement and comparative study with X-ray estimates

We present a dynamical study of the intermediate polar cataclysmic variable YY Dra based on time-series observations in the $K$ band, where the donor star is known to be the major flux contributor. We covered the $3.97$-h orbital cycle with 44 spectra taken between $2020$ and $2022$ and two epochs of photometry observed in 2021 March and May. One of the light curves was simultaneously obtained with spectroscopy to better account for the effects of irradiation of the donor star and the presence of accretion light. From the spectroscopy, we derived the radial velocity curve of the donor star metallic absorption lines, constrained its spectral type to M0.5$-$M3.5 with no measurable changes in the effective temperature between the irradiated and non-irradiated hemispheres of the star, and measured its projected rotational velocity $v_\mathrm{rot} \sin i = 103 \pm 2 \, \mathrm{km}\,\mathrm{s}^{-1}$. Through simultaneous modelling of the radial velocity and light curves, we derived values for the radial velocity semi-amplitude of the donor star, $K_2 = 188^{+1}_{-2} \, \mathrm{km} \, \mathrm{s}^{-1}$, the donor to white dwarf mass ratio, $q=M_2/M_1 = 0.62 \pm 0.02$, and the orbital inclination, $i={42^{\circ}}^{+2^{\circ}}_{-1^{\circ}}$. These binary parameters yield dynamical masses of $M_{1} = 0.99^{+0.10}_{-0.09} \, \mathrm{M}_{\odot}$ and $M_2 = 0.62^{+0.07}_{-0.06} \, \mathrm{M}_{\odot}$ ($68$ per cent confidence level). As found for the intermediate polars GK Per and XY Ari, the white dwarf dynamical mass in YY Dra significantly differs from several estimates obtained by modelling the X-ray spectral continuum.

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arXiv2024

Searching for stellar cycles on low mass stars using TESS data

We have searched for stellar activity cycles in late low mass M dwarfs (M0--M6) located in the TESS north and south continuous viewing zones using data from sectors 1--61 (Cycle 1 to part way through Cycle 5). We utilise TESS-SPOC data which initially had a cadence of 30 min but reducing to 10 min in Cycles 3. In addition, we require each star to be observed in at least 6 sectors in each North/South Cycle: 1,950 low mass stars meet these criteria. Strong evidence was seen in 245 stars for a very stable photometric variation which we assume to be a signature of the stars rotation period. We did a similar study for Solar-like stars and found that 194 out of 1432 stars had a very stable modulation. We then searched for evidence of a variation in the rotational amplitude. We found 26 low mass stars showed evidence of variability in their photometric amplitude and only one Solar-like star. Some show a monotonic trend over 3--4 yrs whilst other show shorter term variations. We determine the predicted cycle durations of these stars using the relationship found by Irving (2023} using an estimate of the stars Rossby number. Finally we find a marginally statistically significant correlation between the range in the rotational amplitude modulation and the rotation period.

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arXiv2022

Limiting the accretion disk light in two mass transferring hot subdwarf binaries

We report the results from follow-up observations of two Roche-lobe filling hot subdwarf binaries with white dwarf companions predicted to have accretion disks. ZTF J213056.71+442046.5 (ZTF J2130) with a 39-minute period and ZTF J205515.98+465106.5 (ZTF J2055) with a 56-minute period were both discovered as subdwarf binaries with light curves that could only be explained well by including an accretion disk in their models. We performed a detailed high-resolution spectral analysis using Keck/ESI to search for possible accretion features for both objects. We also employed polarimetric analysis using the Nordic Optical Telescope (NOT) for ZTF J2130. We did not find any signatures of an accretion disk in either object, and placed upper limits on the flux contribution and variation in degree of polarisation due to the disk. Owing to the short 39-minute period and availability of photometric data over six years for ZTF J2130, we conducted an extensive $O - C$ timing analysis in an attempt to look for orbital decay due to gravitational wave radiation. No such decay was detected conclusively, and a few more years of data paired with precise and consistent timing measurements were deemed necessary to constrain $\dot P$ observationally.

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arXiv2022

Two decades of optical timing of the shortest-period binary star system HM Cancri

The shortest-period binary star system known to date, RX J0806.3+1527 (HM Cancri), has now been observed in the optical for more than two decades. Although it is thought to be a double degenerate binary undergoing mass transfer, an early surprise was that its orbital frequency, $f_0$, is currently increasing as the result of gravitational wave radiation. This is unusual since it was expected that the mass donor was degenerate and would expand on mass loss, leading to a decreasing $f_0$. We exploit two decades of high-speed photometry to precisely quantify the trajectory of HM Cancri, allowing us to find that $\ddot f_0$ is negative, where $\ddot f_0~=~(-5.38\pm2.10)\times10^{-27}$ Hz s$^{-2}$. Coupled with our positive frequency derivative, we show that mass transfer is counteracting gravitational-wave dominated orbital decay and that HM Cancri will turn around within $2100\pm800\,$yrs from now. We present Hubble Space Telescope ultra-violet spectra which display Lyman-$α$ absorption, indicative of the presence of hydrogen accreted from the donor star. We use these pieces of information to explore a grid of permitted donor and accretor masses with the Modules for Experiments in Stellar Astrophysics suite, finding models in good accordance with many of the observed properties for a cool and initially hydrogen-rich extremely-low-mass white dwarf ($\approx0.17\,$M$_\odot$) coupled with a high accretor mass white dwarf ($\approx 1.0\,$M$_\odot$). Our measurements and models affirm that HM~Cancri is still one of the brightest verification binaries for the Laser Interferometer Space Antenna spacecraft.

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arXiv2022

A magnetic valve at L1 revealed in TESS photometry of the asynchronous polar BY Cam

We present TESS photometry of the asynchronous polar BY Cam, which undergoes a beat-cycle between the 199.384-min white dwarf (WD) spin period and the 201.244-min orbital period. This results in changes in the flow of matter onto the WD. The TESS light curve covers 92% of the beat cycle once and 71% of the beat cycle twice. The strongest photometric signal, at 197.560-min, is ascribed to a side-band period. During times of light-curve stability, the photometry modulates at the spin frequency, supporting our WD spin-period identification. Both one-pole and two-pole accretion configurations repeat from one beat cycle to the next with clear and repeatable beat-phase dependent intensity variations. To explain these, we propose the operation of a magnetic valve at L1. The magnetic valve modulates the mass-transfer rate, as evidenced by a factor of 5 variation in orbital-averaged intensity, over the course of the beat cycle in a repeatable manner. The accretion stream threading distance from the WD is also modulated at the beat-period, because of the variation of the WD magnetic field with respect to the stream and because of changes in the mass transfer rate due to the operation of the magnetic valve. Changes in the threading distance result in significant shifts in the position of accreting spots around the beat cycle. As a consequence, only the faintest photometric minima allow for an accurate ephemeris determination. Three regions on the white dwarf appear to receive most of the accretion flow, suggestive of a complex WD magnetic field.

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arXiv2022

A TESS search for donor-star pulsations in High-Mass X-ray Binaries

Ground-based optical photometry of the counterparts of High-Mass X-ray Binaries (HMXBs) has revealed the presence of periodic modulations on timescales of ~0.3-0.5 d. More recent space-based observations Corot and TESS of OB and Be stars have shown that pulsations caused by p and g modes are common in early type stars. We have therefore undertaken a systematic search for variability in the optical counterparts of 23 HMXBs (mostly neutron star systems, but including one black hole, Cyg X-1) using TESS data primarily in 2 min cadence mode. After removing the orbital period modulation in four systems, we find that all 23 sources show evidence for quasi-periodic variability on periods shorter than ~1 d. We compare their power spectra with those from observations of other OB and Be type stars. In two systems, V725 Tau and HD 249179 (which may not be a HMXB), we find evidence for an outburst, the former being simultaneous with an X-ray flare. We search for changes in the power spectra over the outburst duration, and compare them with outbursts seen in other Be systems.

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arXiv2022

Circular Polarimetry of Suspect Wind-accreting Magnetic pre-Polars

We present results from a circular polarimetric survey of candidate detached magnetic white dwarf - M dwarf binaries obtained using the Nordic Optical Telescope, La Palma. We obtained phase resolved spectropolarimetry and imaging polarimetry of seven systems, five of which show clearly variable circular polarisation. The data indicate that these targets have white dwarfs with magnetic field strengths > 80 MG. Our study reveals that cyclotron emission can dominate the optical luminosity at wavelengths corresponding to the cyclotron emission harmonics, even in systems where the white dwarfs are only wind-accreting. This implies that a very significant fraction of the the stellar wind of the companion star is captured by the magnetic white dwarf reducing the magnetic braking in pre-CVs. Furthermore, the polarimetric confirmation of several detached, wind-accreting magnetic systems provides observational constraints on the models of magnetic CV evolution and white dwarf magnetic field generation. We also find that the white dwarf magnetic field configuration in at least two of these systems appears to be very complex.

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arXiv2022

The Puzzling Story of Flare Inactive Ultra Fast Rotating M dwarfs. II. Searching for radial velocity variations

Observations made using TESS revealed a sample of low mass stars which show a periodic modulation on a period $<0.2$~d. Surprisingly many of these Ultra Fast Rotating (UFR) stars showed no evidence of flare activity which would be expected from such rapidly rotating stars. We present results from a spectroscopic survey of UFRs using the Nordic Optical Telescope to search for radial velocity variations which could reveal evidence for binarity. Our sample of 29 sources have a photometric period between 0.1-0.2d, cover spectral classes of M0-4V, and show no evidence for flares. We detect only one source with clear radial velocity shifts, with another two having Gaia RUWE values which suggests they are binaries. Further observations reveal the former star possibly contains a brown dwarf companion with a mass of M$_2$>58 M$_{\rm Jup}$ and probability P(M$_2$<90 M$_{\rm Jup}$) = 50\%. There is no evidence for the companion in our spectra, strengthening the case for a brown dwarf companion. We also examine the folded TESS light curves of all our targets, finding at least two are eclipsing binaries and one which has been contaminated by a spatially nearby $δ$ Sct star. We estimate that around 1/4 of our targets may have been contaminated by short period variable stars. However, the majority of our targets are consistent with being single, low mass stars whose variability is due to starspots. We outline the possible reasons why they are not flare active despite being such rapid rotators.

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arXiv2022

The Puzzling Story of Flare Inactive Ultra Fast Rotating M dwarfs. I. Exploring their Magnetic Fields

Stars which are rapidly rotating are expected to show high levels of activity according to the activity-rotation relation. However, previous TESS studies have found Ultra Fast Rotating (UFR) M dwarfs with periods less than one day displaying low levels of flaring activity. As a result, in this study, we utilise VLT/FORS2 spectropolarimetric data of ten M dwarf UFR stars between spectral types $\sim$M2 - M6 all with $P_{\rm rot} <$ 1, to detect the presence of a magnetic field. We divide our sample into rotation period bins of equal size, with one star having many more flares in the TESS lightcurve than the other. We also provide an analysis of the long-term variability within our sample using TESS lightcurves taken during Cycles 1 and 3 (up to three years apart). We identify 605 flares from our sample which have energies between 2.0$\times$10$^{31}$ and 5.4$\times$10$^{34}$ erg. Although we find no significance difference in the flare rate between the Cycles, two of our targets display changes in their lightcurve morphology, potentially caused by a difference in the spot distribution. Overall, we find five stars (50%) in our sample have a detectable magnetic field with strengths $\sim$1 - 2 kG. Of these five, four were the more flare active stars within the period bins with one being the less flare active star. It would appear the magnetic field strength may not be the answer to the lack of flaring activity and supersaturation or magnetic field configuration may play a role. However, it is clear the relationship between rotation and activity is more complex than a steady decrease over time.

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arXiv2021

Optical detection of the rapidly spinning white dwarf in V1460 Her

Accreting magnetic white dwarfs offer an opportunity to understand the interplay between spin-up and spin-down torques in binary systems. Monitoring of the white dwarf spin may reveal whether the white dwarf spin is currently in a state of near-equilibrium, or of uni-directional evolution towards longer or shorter periods, reflecting the recent history of the system and providing constraints for evolutionary models. This makes the monitoring of the spin history of magnetic white dwarfs of high interest. In this paper we report the results of a campaign of follow-up optical photometry to detect and track the 39 sec white dwarf spin pulses recently discovered in Hubble Space Telescope data of the cataclysmic variable V1460 Her. We find the spin pulsations to be present in g-band photometry at a typical amplitude of 0.4%. Under favourable observing conditions, the spin signal is detectable using 2-meter class telescopes. We measured pulse-arrival times for all our observations, which allowed us to derive a precise ephemeris for the white dwarf spin. We have also derived an orbital modulation correction that can be applied to the measurements. With our limited baseline of just over four years, we detect no evidence yet for spin-up or spin-down of the white dwarf, obtaining a lower limit of |P/Pdot|> 4e7 years, which is already 4 to 8 times longer than the timescales measured in two other cataclysmic variable systems containing rapidly rotating white dwarfs, AE Aqr and AR Sco.

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